Sunetting made simple by larry newcomer, Penns State University

Subnetting Made Simple
IP Subnetting without Tables, Tools, or Tribulations
Larry Newcomer
The Pennsylvania State University
York Campus
Abstract
Every networking professional should have a thorough understanding of TCP/IP subnetting. Subnetting can improve network performance by splitting up collision and broadcast domains. Subnets can reflect organizational structure and help support security policies. WAN links typically join different subnets. Subnets can define administrative units and hence support the structuring and delegation of administrative tasks. Unfortunately, mastering subnetting can pose difficulties for both professionals and students because of the binary mathematics that underlies the technology. While it is imperative to present subnetting concepts in terms of the underlying binary representation, most texts also present subnetting procedures in binary terms. Such an approach can make it difficult for students to learn how to actually carry out subnetting without tables or other reference materials, even when they understand the basic concepts. This paper presents a simple, alternative method for understanding and implementing subnetting without software, calculators, tables, or other aids. The only knowledge of binary arithmetic required is familiarity with the powers of 2 from 0 to 8 (2x for x = 0, 1, …, 8). With a little decimal arithmetic thrown in, the whole process is simple enough to be carried out mentally. This paper assumes the reader is already somewhat familiar with IP addressing, the role of subnet masks, and the uses for subnetting. It proceeds quickly from a brief introduction to a thorough discussion of simple techniques for determining the number of subnets and hosts, calculating the subnet mask, determining (sub)network id’s, and figuring the available IP addresses for each subnet. The methodology is helpful both to those who aspire to be network professionals and to those who seek a simple way to teach subnetting in networking courses.
Introduction
Every networking student should have a solid understanding of TCP/IP subnetting (Loshin, 1997). Subnetting’s importance in modern networking is reflected by its many and varied uses. It can enhance network performance by splitting up collision and broadcast domains in a routed network (Odom, 2000). Large networks can be organized into separate subnets representing departmental, geographical, functional, or other divisions (Feit, 1997). Since hosts on different subnets can only access each other through routers, which can be configured to apply security restrictions, subnetting can also serve as a tool for implementing security policies (Bulette, 1998). Dividing a large network into subnets and delegating administrative responsibility for each subnet can make administration of a large network easier. Routers can require that a WAN link connecting two networks must itself form a separate subnet (Bulette, 1998). Troubleshooting, diagnosing, and fixing problems in a TCP/IP internetwork typically require thorough familiarity with subnetting. Network design requires both the ability to understand and carry out subnetting.
A major stumbling block to successful subnetting is often a lack of understanding of the underlying binary math. In fact, the principles of subnetting are difficult to grasp without mastery of binary arithmetic, logic, and binary/decimal conversions. On the other hand, it is not necessary to be able to think in binary in order to plan, design, and implement simple subnetting. The methodology discussed below allows anyone with the following capabilities to successfully carry out all the subnetting essentials:
• Know the decimal values of the powers of 2 from 0 to 8 as presented in Table 1 below (e.g., 24 = 16)
• Know how to add and subtract the decimal values of the powers of 2 in the following table (e.g., 27 – 25 = 128 – 32 = 96). If this decimal arithmetic can be done mentally, then subnetting itself can be accomplished mentally.
Table 1
x 2x 2x in Decimal
0 20 1
1 21 2
2 22 4
3 23 8
4 24 16
5 25 32
6 26 64
7 27 128
8 28 256
It is helpful to memorize Table 1 before proceeding. The discussion below presents a simple, step-by-step methodology for determining the number of subnets, the maximum number of hosts per subnet, the subnet mask, the network id’s, and the valid IP addresses for each subnet. In short, the method covers all the major steps in the subnetting process. First, however, we present a rapid review of subnetting concepts.
Simple Subnetting Concepts
Before discussing the subnetting procedure, it is necessary to become familiar with the basic concepts of IP addressing, subnet masks, and the separation of an IP address into a network ID and a host ID. An IPv4 (IP version 4) address consists of a 32-bit binary number, which can be viewed as a series of 4 octets (Odom, 1999). Each octet consists of 8 bits, so 4 octets make up 4 * 8 = 32 bits, the exact number of bits in an IP address.
Since IP addressing operates at the OSI network layer (Layer 3), IP addresses must be able to identify both individual hosts (the TCP/IP term for any device connected by a network adapter to a TCP/IP network, such as a computer, printer, router, etc.) and individual networks. This is accomplished by dividing the 32-bit IP addresses into two parts: an initial network ID portion that identifies (i.e., addresses) individual networks, followed by a host ID portion that identifies (i.e., addresses) individual hosts on a given network (Lammle, 2000). Thus IP addressing works by uniquely specifying:
a) A particular TCP/IP network as identified by the network ID portion of the IP address
b) A particular host on that network as identified by the host ID portion of the IP address
It is critical to understand the difference between the MAC address (also known as the hardware, physical, or NIC address) at the Data-Link layer (Layer 2), and the IP address which operates at the Network layer (Layer 3). The MAC address uniquely identifies each network adapter (NIC or Network Interface Card) with a 48-bit binary number. The assignment of MAC addresses is supervised by the IEEE to ensure worldwide uniqueness. Each MAC address consists of two parts: the first part uniquely identifies the NIC manufacturer, and the second part uniquely identifies each NIC produced by a given manufacturer (Poplar, 2000). A device attached to a TCP/IP network via a NIC is called a TCP/IP host. Note that the MAC addressing scheme does not provide a way to identify individual networks, only individual hosts.
With IP addressing, individual hosts can still be uniquely identified, but in a different way. Hosts are identified by specifying both: a) the network on which the host resides (the network id), plus b) a unique host number on that network (the host ID). Thus Layer 3 devices can work either with individual networks by using just the network ID (the beginning portion of the IP address), or with individual hosts by using both the network ID and host ID, i.e., the entire IP address (Heywood, 1997).
Network layer (Layer 3) software and devices thus must be able to separate IP addresses into their network ID and host ID portions. This is accomplished with the help of another 32-bit binary number called a subnet mask. The job of the subnet mask is to tell which part of the IP address is the network ID, and which part is the host ID. Since the network ID is always the leading part of an IP address and the host ID is always the trailing part, a simple masking scheme can be used (Dulaney, 1998). A subnet mask always consists of a series of uninterrupted 1 bits followed by a series of uninterrupted 0 bits. These two portions of the subnet mask (all 1’s and all 0’s) correspond to the two parts of an IP address. The 1 bits in the subnet mask match up with the Network ID, and the 0 bits in the subnet mask match up with the Host ID in the IP address. By looking at the subnet mask, it is easy to tell which part of an IP address represents the network ID and which part represents the host ID. The following example illustrates the use of a subnet mask to separate the network ID and host ID portions of an IP address for a standard Class B network (for Class B networks the first 2 octets of the IP address make up the network ID and the last 2 octets make up the host ID):
32-bit IP Address: 10010010101010000000000000000111
32-bit Subnet Mask: 11111111111111110000000000000000
To enhance clarity we repeat the example above, this time adding some white space between the octets in both the IP address and the subnet mask:
IP Address: 10010010 10101000 00000000 00000111
Subnet Mask: 11111111 11111111 00000000 00000000
Observe how the subnet mask consists of 2 octets of uninterrupted 1’s (indicating the network ID part of the corresponding IP address), and 2 octets of uninterrupted 0’s (indicating the host ID part of the corresponding IP address). Using the subnet mask, we can readily separate the IP address into its two parts:
Network ID: 10010010 10101000
Host ID: 00000000 00000111
Although it is easiest to understand the role of the subnet mask while working in binary, binary notation is in general too cumbersome for humans. Hence IP addresses and subnet masks are usually written in dotted-decimal notation (Cunningham, 1998), in which each octet is converted to its equivalent decimal number, and the four decimal numbers are separated with dots (i.e., periods). The IP address and subnet mask from the example above would appear in dotted-decimal as:
IP Address: 146.168.0.7
Subnet Mask: 255.255.0.0
Network ID: 146.168
Host ID: 0.7
Note that the network ID is usually seen written as 4 octets (which can be created by appending any necessary 0 octets to the end of the network ID as delimited by the subnet mask), and that leading 0 octets are usually dropped from the host ID, as in:
Network ID: 146.168.0.0
Host ID: 7
It is also important to remember that the octet 00000000 in binary becomes 0 in dotted-decimal notation, and the octet 11111111 in binary becomes 255 in dotted-decimal notation.
Finally, we consider the basic concepts of subnetting. Imagine that your organization has obtained an official “public” network address from your Internet Service Provider (ISP) for your organization to use on the Public Internet. You could equally well imagine that your organization has chosen a “private” IP address to use for an internal TCP/IP network that will not be connected to the Public Internet (i.e., an intranet). In either scenario, you have the same problem: Your organization has enough hosts that they cannot, for a variety of reasons beyond the scope of this paper, coexist on the same TCP/IP network (Craft, 1998). The network must be broken up (or segmented) into separate subnetworks. Reasons to segment a large network may include such things as: reducing the size of collision domains, reducing the size of broadcast domains, implementing security, organizing subnetworks to reflect corporate structures, joining networks across WAN links, and segmenting network administration responsibilities (Bulette, 1998).
To segment the original network, we must devise an addressing scheme that is able to identify each subnetwork within the (original) larger network. This will require the use of an additional subnet ID along with the original network ID. A Given host will then be uniquely identified by the combination of:
1. A network ID that uniquely specifies the network on which the host resides (if the network is on the public Internet, this network ID is the address that will identify the network (including all its subnets) on the public Internet)
2. A subnet ID that uniquely specifies the subnetwork (within the original network in item 1 above) on which the host resides
3. A host ID that uniquely specifies the host on the subnetwork in item 2 above
An IP address already accommodates a network ID and a host ID, so all that is required is some way to create the subnet ID field. Since we can’t expand the size of the IP address (32 bits for IPv4), we most “borrow” some bits from the existing address to use for the subnet ID. We can’t borrow bits from the network ID part of the IP address because this has been pre-assigned by our ISP to uniquely identify our organization’s network. Changing the network ID would wreck our ISP’s assignments of network ID’s to the ISP’s customers. Hence we are forced to borrow bits to create the subnet ID from the existing host ID field.
The process of borrowing bits from the host ID field to form a new subnet ID field is known as subnetting. The process is shown in Table 2 below:
Table 2
Network ID 3 Bits Borrowed for Subnet ID Host ID (3 bits Shorter)
10010010 10101000 000 00000 00000111
Notice that when we “borrow” bits from the host ID for the subnet ID, the original subnet mask is no longer accurate. As shown in Table 3 below, the original subnet mask has binary 0’s matching up with the bits in the new Subnet ID. Since binary 0’s in the subnet mask indicate the Host ID field, the newly created “Subnet ID” field still appears to belong to the original Host ID field.
Table 3
Network ID 3 Bits Borrowed for Subnet ID Host ID (3 Bits Shorter)
IP Address: 10010010 10101000 000 00000 00000111
Original
Subnet Mask: 11111111 11111111 000
(0 bits here make subnet ID appear to be part of host ID) 00000 00000000
To eliminate confusion over what bits still belong to the original Host ID field and what bits belong to the new Subnet ID field, we must extend the binary 1’s in the original Subnet Mask with enough 1 bits to match the size of the newly created Subnet ID field (and correspondingly reduce the number of 0’s which originally identified the Host ID in the Subnet Mask by the same amount). The new subnet mask is called a custom subnet mask. After this adjustment, the total number of bits in the custom subnet mask will still be 32, but the number of binary 1’s will have increased by the size of the subnet ID, and the number of binary 0’s will have decreased accordingly. This operation is illustrated in Table 4 below:
Table 4
Network ID Bits Borrowed for Subnet ID Shortened Host ID
IP Address: 10010010 10101000 000 00000 00000111
Original
Subnet Mask: 11111111 11111111 000 00000 00000000
Custom
Subnet Mask 11111111 11111111 111
(1 bits here indicate field belongs to network ID) 00000 00000000
A critical issue when “borrowing” bits from the host ID to create the subnet ID is to accurately determine the following information:
1. How many subnets are needed
2. How many bits must be “borrowed” from the host ID field for the new subnet ID field to accommodate the required number of subnets
3. What is the largest number of hosts that will ever be on a given subnet
4. How many bits must be retained in the host ID field to accommodate the maximum number of hosts needed
These considerations mandate that careful planning should be carried out before the subnetting process is begun. It is obviously prudent to plan for future as well as for current needs. Once pre-planning is complete, the actual subnetting process involves the following steps:
1. Determine how many subnets are needed
2. Determine the maximum number of hosts that will be on any given subnet
3. Determine how many bits to borrow from the host ID field for the subnet ID field
4. Determine how many bits must remain in the host ID field (and therefore cannot be borrowed for the subnet ID)
5. Determine how many bits are in the original network ID and host ID fields
6. Check to ensure that the number of bits to be “borrowed” from the host ID does not exceed the number of bits to be retained for the host ID (i.e., check that the subnetting problem is solvable)
7. Set an optimal length for the subnet ID field, including room for future growth
8. Create a modified (custom) subnet mask for the network
9. Determine the valid subnet ID’s for the network
10. Determine the valid ranges of IP addresses for each subnet on the network
A Simple Subnetting Procedure
The following step-by-step procedure can be used to subnet a TCP/IP network. It is assumed that the reader is already familiar with IP addressing, subnet masks, the separation of an IP address into a network ID and a host ID, and basic subnet concepts as discussed above.
1. Determine the required number of subnets and call it S (“big S”)
When estimating the required number of subnets, it is critical to consider not only your current subnet needs, but also to plan for future growth. If there is historical information available, use it as a guide to predict how many subnets will be needed next year, two years from now, three, etc. Remember to include both current and anticipated subnetworks in your total. If your WAN links are handled as separate subnets, then count each WAN link too.
Remember to leave plenty of room for growth. Nothing is more embarrassing (and costly) than to have to redo a network design because of poor planning. Work closely with users and management to uncover upcoming changes that might affect future growth in ways not shown by historical data (such as an anticipated merger or acquisition, introduction of a new product line, etc.). In the steps that follow, assume that S = 5.
2. Determine the maximum number of hosts per subnet and call it H (“big H”)
In TCP/IP terminology, a “host” is any device that attaches to the network via a network interface. The count should reflect the largest number of network interfaces that will ever be on a given subnet. Remember to include not only network interfaces for computers, but also any network interfaces in printers, routers, or any other networked devices. Some computers (called multihomed hosts) may have more than one NIC, in which case each NIC is counted separately. Other devices (such as bridges or routers) will also have more than one network interface.
It is not necessary to tabulate the number of network interfaces for every subnet. The purpose of step 2 is to count the maximum number of interfaces that will ever be needed for the largest subnet.
As with step 1, remember to plan for growth. Use historical data if available, but also look for upcoming changes that could lead to significant growth not reflected in the historical data. Again, nothing is more embarrassing than to have to redo a network design because of poor planning. In the steps that follow, assume that H = 50.
3. Find the smallest integer s (“little s”) such that 2s – 2 ≥ S
This step calculates the number of bits s (“little s”) needed in the IP address for the subnet ID’s. “Little s” is the smallest integer (whole number) such that 2s – 2 is at least S (“big S”, the required number of subnets). As the following table illustrates, with s bits for the subnet ID, we can address 2s different subnets. However, a subnet ID is not allowed to be either all 0’s (which according to TCP/IP standards always means the current subnet and therefore cannot be used as a subnet ID for an actual subnet), or all 1’s (which according to TCP/IP standards is always a broadcast address and therefore cannot be used as a subnet ID for an actual subnet) (Heywood, 1997). Hence with s bits for the subnet ID, the effective number of addressable subnets is 2s – 2, as shown in Table 5 below:
Table 5
s = number of bits for subnet ID 2s – 2 = number of addressable subnets Valid subnet addresses (all 0s or all 1’s are invalid and are shown crossed out)
1
(produces no valid addresses) 21 – 2 = 2 – 2 = 0 0
1
2 22 – 2 = 4 – 2 = 2 00
01
10
11
3 23 – 2 = 8 – 2 = 6 000
001
010
011
100
101
110
111

Calculating s is easier if we rewrite the inequality 2s – 2 ≥ S as 2s ≥ S + 2. If you are comfortable with the entries in Table 1, you can quickly find the smallest s such that 2s ≥ S + 2 as follows:
1. Find the smallest integer value in the right-hand column of Table 1 that is equal to or greater than S + 2 (“big S” plus 2)
2. Using Table 1, find the corresponding value of s (“little s”) from the left-hand column
3. This is the number of bits needed for the subnet ID’s in your IP addresses
For example, if S = 5, the smallest integer value from the right-hand column of Table 1 that is ≥ 5 + 2 = 7 is 8. The corresponding value of s (from the left-hand column of Table 1) is 3. If on the other hand S = 7, the smallest integer value from the right-hand column of Table 1 that is greater than or equal to 7 + 2 = 9 is 16. Hence the value of s is 4.
4. Find the smallest integer h (“little h”) such that 2h – 2 ≥ H
This step calculates the number of bits h (“little h”) needed in the IP address for the host ID’s, and is similar to step 3. In fact, the TCP/IP standards state that a host ID cannot be all 0’s, since a 0 host ID always refers to the current host (and so can never be used as the address for a particular host), or all 1’s, since all 1’s indicates a broadcast address (and so can never be used for the address of a particular host) (Heywood, 1997). Hence the formula for finding the number of bits needed for the host ID’s is exactly parallel to that used to calculate the number of bits needed for the subnet ID’s. Similar to step 3, we look for the smallest integer h such that 2h – 2 ≥ H. By rewriting the inequality as 2h ≥ H + 2, we can use a parallel procedure to that in step 3:
1. Find the smallest integer value in the right-hand column of Table 1 that is equal to or greater than H + 2 (“big H” plus 2)
2. Using Table 1, find the corresponding value of h (“little h”) from the left-hand column
3. This is the number of bits needed for the host ID’s in your IP addresses
For example, if H = 50, the smallest integer value from the right-hand column of Table 1 that is ≥ 50 + 2 = 52 is 64. The corresponding value of h (from the left-hand column of Table 1) is 6. If on the other hand H = 30, the smallest integer from the right-hand column of Table 1 that is greater than or equal to H + 2 = 30 + 2 = 32 is 32. Hence h = 5.
5. Determine the total number of host ID bits in the standard subnet mask for your assigned address class. Call the number of host ID bits T (“big T”).
Table 6 below shows the standard number of Host ID bits for each of the three major address classes, A, B, and C. To determine the address class of a network ID, look at the first octet in dotted-decimal notation. As Table 6 shows, if the first octet is between 1 – 126, the network is Class A; if the first octet is between 128 – 191, the network is Class B; if the first octet is between 192 – 223, the network is Class C. Once you know the address class, it is easy to determine the number of host ID bits from Table 6. For example, if you have been officially assigned a Class B address, T = 16; if you have been officially assigned a Class C address, T = 8; etc. To do mental subnetting, it is helpful to memorize Table 6.
Table 6
Address Class Starting Octet for Network ID
(in decimal) Network ID Bits in Standard Subnet Mask Host ID Bits in Standard Subnet Mask (T)
A 1 – 126 8 24
B 128 – 191 16 16
C 192 - 223 24 8
For example, assume the official network ID is 146.168.0.0. According to Table 6, this is a Class B address (since 146 is between 128 – 191, inclusive) and the number of host ID bits in the standard subnet mask is T = 16.
6. If s + h > T, then you need more host ID bits than are available for your official address class. You cannot meet your subnetting requirements (i.e., the problem is not solvable using your assigned address class)
In this case your officially assigned Network ID requires so many bits in the IP address that there are not enough bits left over to satisfy your needs for subnet ID’s and host ID’s. In short, your subnetting requirements S (”big S”) and H (“big H”) when taken together are too large for your assigned address class. You will either have to reduce the values of S and/or H, or apply for an official network ID that requires fewer network ID bits and leaves more host ID bits (i.e., change from class C to class B, or from class B to class A). If s + h > T, start over again at step 1 after changing your requirements (i.e., the estimated number of subnets and/or the maximum required number of hosts per subnet), and/or changing your officially assigned address class.
In our example, T = 16, s = 3, and h = 6. Hence s + h = 3 + 6 = 9, which is not greater than T = 16. Hence we can proceed to the next step.
7. If s + h = T, skip the next step (step 8)
You have exactly enough bits for the desired subnetting. Skip step 8 and go on to step 9. In our example, s + h = 3 + 6 = 9 and T = 16, so we must carry out step 8.
8. If s + h < T, then you have T – s – h “extra” bits to distribute between s and h in a manner that best provides for unanticipated future growth. Calculate r (“little r”) as r = T – s – h, the number of bits that you can deploy either for extra subnet ID bits and/or for extra host ID bits, then increase s and/or h accordingly
You have r (“little r”) bits to distribute between s (“little s”, the number of bits needed for subnet ID’s) and h (“little h”, the number of bits needed for host ID’s). Increase s and/or h until you’ve used up all r bits (at which point T = s + h, as in step 7).
Since you are more likely to run out of subnets before you run out of host ID’s on any given subnet, it is probably safer to make sure that s is comfortably large before increasing h. Assume that at the beginning of step 8, T = 16, s = 7, and h = 6. You then have T – s – h = 16 – 7 – 6 = 3 bits to distribute between s and h. Since it is probably a safer hedge to increase s, you might give 2 of the 3 “extra” bits to s (making s = 9), and give 1 of the 3 extra bits to h (making h = 7). If done correctly, the new values of s and h will sum to T (9 + 7 = 16).
In the example we’ve been following from previous steps, r = T – s – h = 16 – 3 – 6 = 7 bits to distribute between s and h. We will increase s by 1 (making the new value of s = 4), and increase h by 6 (making the new value of h = 12). Since it is often more important to increase s than to increase h, we should carefully question our decision to increase s by only one. Let us assume that we have a very high degree of confidence in our original estimate for S, but are less sure of our original estimate for H. Hence we (perhaps atypically) decide to favor h over s in this step.
9. Determine the custom subnet mask for your network
Start with the default (standard) subnet mask for your address class as shown in Table 7 below: We will extend the network ID portion of the default subnet mask by replacing its leftmost zero octet (shown bolded in the table) with a new value.
Table 7
Address Class Default Subnet Mask Leftmost Zero Octet
A 255.0.0.0 255.0.0.0
B 255.255.0.0 255.255.0.0
C 255.255.255.0 255.255.255.0
Calculate the new value for the leftmost zero octet in the standard subnet mask as:
256 – 28 - s
For example, if the adjusted value of s is 4, we calculate 256 – 28 – 4 = 256 – 24 = 256 – 16 = 240. This value will replace the leftmost zero octet in the default subnet mask for our network class, thus forming the custom subnet mask. Since in Step 5 we determined that our network ID was Class B, our default subnet mask from Table 7 is 255.255.0.0. Replace the leftmost zero octet (shown bolded) with the value 240 to obtain the custom subnet mask 255.255.240.0.
10. Determine the Valid Network ID’s for the New Subnets
The next step is to determine the network (and subnetwork) ID’s for the new subnets. Start by identifying the leftmost 0 octet in the original network ID for your network (expressed as four octets in dotted-decimal). This is the octet that corresponds to the leftmost 0 octet in the standard subnet mask (i.e., the octet shown bolded in Table 7). For the original subnet mask in our example, it would be the third octet from the left (shown bolded): 146.168.0.0. For a Class A network, this will always be the second octet (as in 13.0.0.0), for a class B network, this will always be the third octet (as in 146.168.0.0), and for a Class C network, this will always be the fourth octet (as in 193.200.17.0).
Note this particular octet will always have all 0’s in the extended subnet ID area (the area “borrowed” from the original host ID), and so is not a valid subnetwork ID (recall that a zero value is not permitted for either a network or subnetwork ID).
To obtain the first valid subnetwork ID, add 28 – s to the leftmost 0 octet (as identified above) in the original network address. Now add 28 – s to the same octet in the first subnetwork ID to get the second subnetwork ID, add 28 – s to the same octet in the second to get the third, etc. Continue in this fashion until you have obtained 2s – 2 subnetwork ID’s, or until you reach the value of your custom subnet mask. Note that the custom subnet mask value itself is not a valid network ID because the subnet ID is all 1’s (the reserved broadcast address).
In our example, the original network ID is 146.168.0.0 (the leftmost zero octet is shown bolded), the updated value of s is 4, and 28 – s = 28 – 4 = 24 = 16. We expect 2s – 2 = 24 – 2 = 16 – 2 = 14 subnets, which we find as follows:
The first network ID is obtained by adding 28 – s (i.e., 16) to the leftmost 0 octet in the original network address, forming the first network ID, i.e., add 16 to the third octet (shown bolded) in 146.168.0.0 to yield
146.168.16.0 (first valid subnet ID)
The second subnet ID is obtained by adding 28 – s (16) to the same octet in the first valid subnet ID (shown bolded above), i.e., add 16 to the third octet (shown bolded) in 146.168.16.0 to yield
146.168.32.0
To form the third network ID, again add 28 – s (16) to the same octet in the second valid subnet ID (shown bolded above), i.e., add 16 to the bolded octet in 146.168.32.0 to yield
146.168.48.0
Repeat this procedure until you have obtained the expected 14 subnetwork addresses (or until you reach the custom subnet mask from Step 9). The results are shown in Table 8 below:
Table 8
Original Network ID
(Not a valid subnetwork address) 146.168.0.0
Network ID for Subnet 1 146.168.16.0
Network ID for Subnet 2 146.168.32.0
Network ID for Subnet 3 146.168.48.0
Network ID for Subnet 4 146.168.64.0
Network ID for Subnet 5 146.168.80.0
Network ID for Subnet 6 146.168.96.0
Network ID for Subnet 7 146.168.112.0
Network ID for Subnet 8 146.168.128.0
Network ID for Subnet 9 146.168.144.0
Network ID for Subnet 10 146.168.160.0
Network ID for Subnet 11 146.168.176.0
Network ID for Subnet 12 146.168.192.0
Network ID for Subnet 13 146.168.208.0
Network ID for Subnet 14 146.168.224.0
Custom Subnet Mask value
(Not a valid subnetwork address) 146.168.240.0

11. Determine the Valid IP Addresses for Each Subnet
The final step in subnetting is to determine the valid IP addresses for each new subnetwork. To generate the valid IP addresses for a given subnetwork, start with that subnetwork’s network address (as shown in Table 8, for example). Add 1 to the rightmost octet in the subnet address to obtain the first valid IP address on that subnet. In our example:
Network ID of first subnet: 146.168.16.0
First valid IP address on that subnet: 146.168.16.1
Continue to add 1 to the rightmost octet until one of the following three conditions occurs:
1. The octet that you are incrementing reaches 255. When incrementing the value 255, instead of adding 1 (to get 256), roll the 255 back to 0 and add 1 to the next octet to the left. This operation is similar to a carry in ordinary decimal addition. For example, assume you have just added 1 to 146.168.16.254 to obtain 146.168.16.255. The next step would not be to add 1 again to obtain 146.168.16.256 (which is not a valid IP address). Instead, roll the 255 back to 0 and add 1 to the next octet to the left (the 16), yielding 146.168.17.0. From this point, continue to increment as before to obtain additional IP addresses for the current subnet
2. While incrementing, you get to the point where another increment would reach one less than the network ID for the next subnet. In this case, you have listed all the valid IP addresses for the current subnet, and you must move on to the next subnet (by starting with its network ID and repeatedly incrementing the rightmost octet by 1)
3. You reach a total of 2h – 2 IP addresses for a given subnet. This is equivalent to condition 2 above, and in fact is just another way of looking at the same situation. As in condition 2, you have listed all the valid IP addresses for the current subnet. Move on to the next subnet by starting with its network ID and repeatedly incrementing by 1
Repeat this process for all subnetworks to obtain a complete list of valid IP addresses for each subnet.
In our example, we start with 146.168.16.0, the network ID for the first subnet (see Table 8). Add 1 to the rightmost octet to obtain the first valid IP address for this subnet, namely 146.168.16.1. Again, add 1 to the rightmost octet to obtain the second valid IP address for this subnet, namely 146.168.16.2. Continue in this fashion until reaching 146.168.16.254, which after incrementing yields an IP address of 146.168.16.255. Note that this is a valid IP address on the subnet. The next valid IP address is found by rolling the 255 back to 0 and incrementing the next octet to the left, yielding 146.168.17.0. Continue incrementing until reaching 146.168.17.255, which is followed by 146.168.18.0. Again, the process repeats until we hit 146.168.18.255, which is followed by 146.168.19.0. This process will continue all the way to 146.168.30.255, which is followed by 146.168.31.0. We continue to increment until reaching 146.168.31.254. We are now at the point where yet another increment would yield one less than the next subnet’s network ID (i.e., if we were to carry out one more increment we would be at 146.168.31.255, which if it were itself incremented would yield the subnet ID for the next subnet, 146.168.32.0). At this point we have a complete list of all valid IP addresses for the first subnet. We would then have to repeat the entire process for the second subnet, etc. Table 9 summarizes the IP addresses for the first subnet:
Table 9
IP Addresses for Subnet 1
(Network Address 146.168.16.0)
146.168.16.1 to 146.168.16.255
146.168.17.0 to 146.168.17.255
146.168.18.0 to 146.168.18.255
146.168.19.0 to 146.168.19.255
146.168.20.0 to 146.168.20.255
146.168.21.0 to 146.168.21.255
…
146.168.30.0 to 146.168.30.255
146.168.31.0 to 146.168.31.254
Do not be confused by the fact that some valid IP addresses end in 0 or 255. This happens normally when subnetting, and the rules about not having network, subnetwork, or host ID’s equal to all 0’s or all 1’s are not necessarily violated just because an octet is equal to all 0’s or all 1’s. The rules place restrictions on the values of network, subnetwork, and host ID’s, not on the values of octets. To understand this, consider the IP address 146.168.17.0 from Table 9 and analyze it according to the custom subnet mask for our example network, 255.255.240.0.
Table 10
Standard Network ID Part of IP Address Bits Borrowed from Host ID to form Subnet ID Part of IP Address Shortened Host ID Part of IP Address
IP Address 146.168.17.0 10010010 10101000 0001 0001 00000000
Custom Subnet Mask 255.255.240.0 11111111 11111111 1111 0000 00000000
Notice that although the rightmost octet of the Host ID consists of all zero bits, the full Host ID is a total of 12 bits and is not all 0’s (the sole one bit is shown bolded).
For a second example, consider the IP address 146.168.21.255 from Table 9. Although the last octet is 255 (eight 1’s in binary), the following analysis shows that the full host ID is not all 1 bits (the two zero bits in the host ID are shown bolded):
Table 11
Standard Network ID Part of IP Address Bits Borrowed from Host ID to form Subnet ID Part of IP Address Shortened Host ID Part of IP Address
IP Address 146.168.21.255 10010010 10101000 0001 0101 11111111
Custom Subnet Mask 255.255.240.0 11111111 11111111 1111 0000 00000000
A Class C Example
Suppose an ISP assigns a Class C network address of 193.200.35.0 to an organization (call it Widgets, Inc., or just Winc). We will work through the 11 steps presented above in order to subnet this Class C network.
1. After meetings with relevant Winc personnel and study of historical growth trends, it is determined that Winc currently needs 2 subnets, with practically no likelihood of adding other subnets in the future. Therefore, we set S (“big S”) at 2.
2. After meetings with relevant Winc personnel and study of historical growth trends, it is determined that Winc currently needs at most 25 hosts on any subnet. In the future, subnet size is not expected to pass 30 hosts. Hence, we set H (“big H”) at 30.
3. To find the smallest integer s such that 2s – 2 ≥ S, we first rewrite the inequality as 2s ≥ S + 2. Since S = 2, this becomes 2s ≥ 2 + 2 or 2s ≥ 4. Reference to Table 1 shows that the smallest such integer s is 2.
4. To find the smallest integer h such that 2h – 2 ≥ H, we first rewrite the inequality as 2h ≥ H + 2. Since H = 30, this becomes 2h ≥ 30 + 2 or 2h ≥ 32. Reference to Table 1 shows that the smallest such integer h is 5.
5. Winc’s assigned network address is 193.200.35.0, which begins with 193. Hence Winc has a Class C network address for which T (“big T”) is 8 (see Table 6).
6. Now we can calculate s + h = 2 + 5 = 7, which does not exceed the value of “big T” (T = 8). Hence we have a solvable subnetting problem and can proceed to step 7.
7. Since s + h = 2 + 5 = 7 which is not equal to 8 (the value of T), we must carry out step 8
8. Since s + h = 2 + 5 = 7 is less than T = 8, we have r = T – s – h = 8 – 2 – 5 = 1 bit left over to increase the value of either s or h. Since in general Winc is more likely to run short of subnets rather than hosts on a subnet, we allocate the extra bit to s, incrementing s so that now s = 3. Note that now s + h = 3 + 5 = 8 = T.
9. To determine the custom subnet mask for Winc’s network, we start with the standard (default) subnet mask for Class C (Winc’s network class), which according to Table 7 is 255.255.255.0. We will replace the leftmost zero octet in the original subnet mask (i.e., the 0 in 255.255.255.0), with a new octet that will extend the subnetwork ID into the host ID. Calculate the new value for the original leftmost zero octet as 256 – 28 – s, which is 256 – 28 – 3 or 256 – 25 or 256 – 32 or 224. Hence the custom subnet mask for Winc’s network is 255.255.255.224.
10. Now we determine the valid network ID’s for the new subnets by identifying the leftmost 0 octet in the original network ID assigned by the ISP. Since this network ID is 193.200.35.0, the leftmost 0 octet (the only 0 octet) is also the rightmost 0 octet (shown bolded). We now add 28 – s = 28 – 3 = 25 = 32 to this 0 octet to get the new value for the octet in the first subnet ID: 32 + 0 = 32. Thus the network ID for the first subnet is
193.200.35.32
We continue adding 28 – s to this octet until we either reach the value of the custom subnet mask (255.255.255.224) or until we have network addresses for 2s – 2 subnets (these two conditions are equivalent and so will occur at the same time). In our case, 2s – 2 = 23 – 2 = 8 – 2 = 6 subnets, so we continue adding 28 – s five more times (for a total of six times) as shown below:
Table 12
Original Network ID (not a valid subnet address since subnet ID is all 0’s) 193.200.35.0
Address for subnet 1 193.200.35.32
Address for subnet 2 193.200.35.64
Address for subnet 3 193.200.35.96
Address for subnet 4 193.200.35.128
Address for subnet 5 193.200.35.160
Address for subnet 6 193.200.35.192
Custom Subnet Mask (not a valid subnet address since subnet ID is all 1’s) 193.200.35.224
11. To determine the valid IP addresses for each subnet, we begin with the network ID for the subnet. Let us start with the first subnet whose address (as seen from Table 12) is 193.200.35.32. To find the first IP address on the subnet, we add 1 to the rightmost octet of the subnet address: 32 + 1 = 33. Thus the first IP address on subnet 1 is
193.200.35.33
We will continue incrementing until we reach 255, or until the next increment would reach two less than the next subnet address, or until we have generated 2h – 2 IP addresses (these last two conditions are equivalent and will always occur at the same time). Since in our case h = 5, we can expect 25 – 2 = 32 – 2 = 30 IP addresses per subnet. The valid IP addresses for subnet 1 are shown in the following table:
Subnet 1 Address # IP Address
1 193.200.35.33
2 193.200.35.34
3 193.200.35.35
4 193.200.35.36
5 193.200.35.37
6 193.200.35.38
7 193.200.35.39
8 193.200.35.40
9 193.200.35.41
10 193.200.35.42
11 193.200.35.43
12 193.200.35.44
13 193.200.35.45
14 193.200.35.46
15 193.200.35.47
16 193.200.35.48
17 193.200.35.49
18 193.200.35.50
19 193.200.35.51
20 193.200.35.52
21 193.200.35.53
22 193.200.35.54
23 193.200.35.55
24 193.200.35.56
25 193.200.35.57
26 193.200.35.58
27 193.200.35.59
28 193.200.35.60
29 193.200.35.61
30 193.200.35.62
Note that if we increment the last octet of the 30th IP address (see Table 12), we get 63, which is one less than the network ID for the next subnet. Hence 193.200.35.62 is indeed the final IP address on subnet 1.
The IP addresses for the remaining 5 subnets can be found in a similar manner.
References
Bulette, G. TCP/IP MCSE Study Guide, Foster City, CA, IDG Books Worldwide, 1998.
Craft, M., Mayo, B., Pherson, J., et. al., CCNA Cisco Certified Network Associate Study Guide (Exam 640-407), Berkeley, CA, Osborne McGraw-Hill, 1998
Cunningham, S., Frederick, B., First, T., et. al., MCSE Microsoft TCP/IP on Windows NT 4.0 Study Guide, Berkeley, CA, Osborne McGraw-Hill, 1998
Dulaney, E., Sherwood, L., Scrimger, R., MCSE Training Guide TCP/IP, Indianapolis, IN, New Riders Publishing, 1998.
Feit, S. TCP/IP, New York, NY, McGraw-Hill, 1997.
Heywood, D., Scrimger, R., Networking with Microsoft TCP/IP Certified Administrator’s Resource Edition, Indianapolis, IN, New Riders Publishing, 1997.
Lammle, T., CCNA Cisco Certified Network Associate Study Guide (Exam 640-507), 2nd ed., Alameda, CA, SYBEX, 2000
Loshin, P. TCP/IP Clearly Explained, San Diego, CA, Academic Press, 1997.
Odom, W., CCNA Exam Certification Guide, Indianapolis, IN, Cisco Press, 1999
Odom, W., Cisco CCNA Exam #640-507 Certification Guide, Indianapolis, IN, Cisco Press, 2000
Poplar, M., Waters, J., McNutt, S., and Stabenaw, D., CCNA Routing and Switching, Scottsdale, AR, Coriolis, 2000

Classed IP addresses

Up to now I had not relizied how that they had divided the classes. Class A address have a zero for the first number of the octet (0-127) (01000000). Class B has a one as the first number of its octet (1000000)(128-191). Class C has a (10) as the first two numbers in first octet (11000000) (192-223). Class D (11100000) (224-239). Class E (11110000) (240-255). The chart on page 78 shows all the classes with clarity. But now I get how they defined them with how the octet numbers break over. For me the class divisions make sense on how they were derived.

Build your own solar panels

For when you would like to operate your computer without paying the electric company to supply the power.
Sunday 14. Feb 2010


Answer this question - Do you want to save thousands off the cost of solar panels?
Of course you do!

You can now make solar panels at home! You have probably read about it or seen it on TV, but have you tried it yourself?

"I just made my own solar panel. It was so simple and looks just like a bought panel"
From the DIY workshop of Michael Harvey
Renewable energy enthusiasts
and co-founder of Earth4Energy.com


Hi, my name is Michael and I want to show you how to go green and save thousands at the same time.

Please click the play button on the below video to learn more >>


f you are interested in learning exactly how to generate power and reduce your bill then this is the perfect resource for you! With the ever increasing costs of living, there is no better time than right now to stop throwing money out the window and start generating our own electricity.
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"A++++"
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THANK YOU EVER SO MUCH FOR THE INSTANT RESPONSE. I HAVE ALL THE INFO I NEED AND THE TEXT IS OVER THE TOP. TOP SHELF IN ALL INFO. A++++ TO YOU FOLKS SINCERELY.

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If you have already contacted your local solar supplier then I'm sure you already know how expensive installation can be.

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I was looking to purchase a few retail solar panels for my home but after looking at the price of them it just made sense to build my own.

After going through your materials I managed to build 2 solar panels for under $100! They are just small panels but this is all I need for the lighting and fridge in my courtyard.

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Sydney, AU.



You don't need to be a builder, anybody can make solar panels. It's really quite easy to make solar panels once you know a few industry secrets. Plus, our guide is broken down into an easy to follow format that will walk you through step-by-step.

We will provide you with plenty of pictures and diagrams for you to look at but if you still need help, just email us! We are more than happy to answer any questions you have.

After we created our solar panel guide we wanted to know if it was easy enough for the "Average joe" to follow.
We found 43 people (male and female) who were interested in solar but knew nothing about making panels, we gave them our guide and came back in a month to see what they have built.

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"My panel produces just over 18 volts"
Hey Guys. Thanks for the solar info. I made a solar panel like you said by using 36 cells in series. My panel produces just over 18 volts which is exactly what I was after. Anyway, keep up the good work. This is great stuff. I have actually told a few work mates about this and we are going to build solar panels and sell them for a neat profit. I will let you know how that goes too!
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Ontario, Canada



Before you get started on your solar energy project you need to make sure you have the right tools. More importantly, you need to make sure you have the correct step-by-step instructions.

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Some people find it hard to believe you can make quality solar panels for less than $200. Well, we have proven it's definitely possible. There are now people from all parts of the world making their own solar panels and saving thousands off retail cost! It really does make sense to build your own solar panels, especially when it's this affordable and easy.

The Earth4Energy product comes in 6 separate parts.
Part 1
Introduction To Solar Energy
In this section you are going to learn the basics of solar energy which includes how solar energy is generated. You are also going to learn about every component needed in a complete solar energy installation.

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Part 2
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By now you will have a great understanding of solar energy so it's time to start building your own solar panel.

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• Detailed plans complete with color diagrams and pictures.

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This package consists of 4 extra resources that will help you along the way.
• The Solar Calculator

We have even developed a solar calculator for you to use. This will show you how many panels you will need to power your home and what size battery bank you will need if you want to go completely off-grid.

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This guide will show you how to fix the solar panels to your roof just like the professionals do. This fully illustrated guide is a must have for a complete and secure install.
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Don't spend hours searching government web sites, we have all the forms ready for you to fill out!
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To safely wire up your solar panels you are going to need to know a few things first, that's why this guide is so important.


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This is a $49 value but today it's included in the Earth4Energy e-kit for free!

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Part 5
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This is a $49 value but today it's included in the Earth4Energy e-kit for free!

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Part 6 - Bonus
Info Video Series
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1 IT WORKS! Our product has been put to the test by thousands of people worldwide. We are the most popular product in this market because our guides are the best available.
2 You can reduce your power bill. By making your own solar panels and/or wind turbines you can combine them and significantly reduce your power bill, you can even eliminate it completely!
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4 Do your part for the environment! If you are looking for a way to go green then this is the perfect resource for you.
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6 Get our video series for free! If you invest in Earth4Energy now you will also get our "Hollywood quality" videos for free. These videos will soon be sold separately for $99 however for a very limited time they are included for free.
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Please order now if you want our 2 hour + info video series included for free. These videos will soon be sold as a seperate product for $99 however for a limited time they are included for free.

Earth4Energy has proven itself to thousands of happy customers and we proudly
stand behind our product. Safely order today with our Iron-Clad Guarantee.

Consider this: If you simply sit back and do nothing you are destined to pay more than you should for electricity. You can save thousands by making your own solar panels and save even more off your power bills.

If your not technically inclined and you think it's going to be too hard than please don't worry. Our video series is very easy to follow as I explain everything during the build process. Here are a few comments we have received over the months from people who thought they could never do it.

"Thanks for adding the videos Mike. They are very helpful" - Sally C.
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+ hundreds of other fantastic feedback from new do it yourself'ers

We also offer a full money back guarantee. Our guarantee is "Love it or it's free!".

Thank you for reading and I hope you decide to get involved in the green energy movement. It's exciting, rewarding and can save you a lot of money.


To our green future,



Michael Harvey
Renewable energy enthusiasts
and creator of Earth4Energy.com
P.S - Earth4Energy has fast become the most popular guide for homemade renewable energy. I have to tell you now that the sale price of $49.97 will not last forever. If you are looking for ways to help save our planet than I urge you to get in while its cheap.

P.P.S - I have also included a special gift for you in the members area. This is my "thank you" for doing your part for our environment. Please make sure you check it out after you join!

P.P.P.S - Remember, we offer a "Love it or it's free" guarantee. If your not happy with the quality of our information just send a simple email to us and we will refund every penny back to your account. No questions asked.

"Earth4Energy blows the other
guides out of the water!"
I actually purchased 2 other guides to building solar panels before I decided to purchase Earth4Energy. I just have to say: Earth4energy blows the other guides out of the water! You have a really good product here.

Thanks for the time and effort put in to making this for us.

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Florida, US




"I am very pleased with
your after sale support"
I am very pleased with your after sale support. I am computer service tech- with 50+ clients, so will spread the news once I know to explain and convince my customers how solar power could save them money too.
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Illinois, US.




"I have just watched your videos
and I'm truly impressed"
Great product guys. I have just watched your videos and I'm truly impressed. I'm really excited about making my solar panel now. I am just going to make a few of them for camping so I can ditch the noisy generator! I will keep in touch and send you a pic of my finished panel!

John Suitor
Perth, AU.




Special note:
How to turn Earth4energy into
your own profitable small business you can run from home!
You can make a simple solar panel for as little as $200 and sell them for $500! So by using the Earth4Energy instructions you can profit over $300 for every solar panel you build.

Think about that for a second - After a bit of practice you can build up to 5 solar panels every week (or even more) and sell them for a profit of $300 each. That's a weekly profit of $1500. This is the perfect business model because not only can you make a decent profit you can pass on your knowledge to others whom want to help our environment.
Don't forget, when you purchase the Earth4Energy kit you also own the rights to build and resell the completed solar panels without paying us a thing. All profits you make will be your own.
This business model will work from any part of the world including your area. People are fed up with paying the electric company and they will be begging for your renewable energy products.
This information is only available in the Earth4Energy kit and not available anywhere else.





The Earth4Energy manual is in PDF format and the video series is in Quicktime and Flash format.

This means you get your product instantly after payment and can start right away. Even if it's 3am in the morning!
CAUTION: Please be aware of copycat products. Earth4Energy is the original manual for your DIY renewable energy solutions. Earth4Energy is the number 1 product in the Clickbank market place for a reason - We put in more effort!


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Packet Tracer

The class on packet tracer was a good beginning. I thought it was just me that was feeling a little lost.

Community Colleges do it better

http://www.green-technology.org/green_technology_magazine/win-win.ht
Green Technology Home








--------------------------------------------------------------------------------



Current photo of LA City College’s new Child Development Center, nearly complete


A Bright Future
The Win-Win-Win of Community College Green Building Programs

By Racquel Palmese

Community colleges find themselves at the nexus of change. Charged with retraining workers for 21st century jobs, community colleges also cope with swelling ranks of students and funding cutbacks. But the bond-driven building and energy retrofit projects underway at California’s community colleges are a win for everyone. They put money into the economy and support contractors, service providers and industry. They help train a new workforce, and enhance and educate their communities. As test beds for experimental technologies, these state-of-the art buildings also advance the development of green products and services.

So far in California, according to the U.S. Green Building Council (USGBC), 40 higher education buildings, comprising almost 748,223,914 square feet, have been certified at various levels of LEED (the USGBC's Leadership in Energy and Environmental Design). Most of them belong to community colleges. The highest scoring building, achieving 55 points for a Platinum certification, is the Newark Center for Health Sciences and Technology at Ohlone College (see related article). Only eight of the building projects settled for the lowest LEED rating (LEED Certified). Eighteen projects achieved Silver, ten got Gold and four made it all the way to Platinum, the highest rating.

But that's only the beginning. There are 408 higher education buildings pursuing LEED certification in California alone, comprising almost 4.5 billion square feet. Many of these belong to community colleges, making a big green dent in the total square footage of the California community college system.

Building Things Left and Right

Contributing enormously to this total is the Los Angeles Community College District (LACCD), which describes its renowned building program as one of the largest public sector sustainable building efforts in the U.S. LACCD is also the largest community college district in the nation, serving 200,000 students per year at its 9 campuses. The district is spending about $6 billion in largely voter-approved funds to build green with the goal of having the whole system eventually become grid neutral, or producing as much electricity as it uses. See related article.

If you attend a conference having to do with green building, or visit a campus with a green building program, chances are you'll run into Larry Eisenberg, the executive director of Facilities Planning and Development for LACCD, presenting on his building program or gathering information in his ongoing pursuit for the newest green technologies and ideas. He's one of the most in-demand speakers on the subject of higher education green building in the US.

Asked how the bond-funded $6 billion green building program at LACCD is going, he said, "fabulously well. We are building things left and right." He's referring to LACCD's 30 current buildings projects, most of which are "design-build," meaning architects, engineers and contractors work in teams, a radical break from the past where they each bid individually, often to the detriment of the projects. "We just had our design-build meeting and it played to a standing room only crowd," Eisenberg said. "There were literally hundreds of people interested in doing business with us."

He admits that the hyperactivity around his building program probably has a lot to do with the shortage of construction jobs right now, but he's glad that the District is a major economic driver, putting money into the community. "There are tens of millions of dollars in projects we're talking about, and we're trying to get as much out on the street as we can right now. This is a great year to build."

It's a great year because prices for construction are coming down - anywhere from 30 - 50 percent below his estimates, says Eisenberg. "We're seeing a return to numbers from the early 2000's. We're being very careful, spending public money in a very dear way."

Construction Costs Down - Alternatives Up

As construction costs come down, money can be freed up for alternative energy projects. Cynthia Hughes-Doyle, a senior associate at Davis Langdon, international cost-management consultants, says that building budgets are typically set, so if a project is coming in under budget, it is possible to include some additional things, like alternative energy. The company's seminal studies on the real cost of green building blew apart previous notions that sustainable features added up to 30 percent to building costs, showing that building green can be done at little or no additional cost.

"We're seeing lower construction bids across the board," says Doyle, "not just in the public sector, but the commercial sector as well. We don't particularly see changes in materials," she continues, "and labor has not been renegotiated as yet. Profits are coming down for the contractors and general contractors. We're telling our clients it's worth it to take a hard look at contingencies you have set aside and the strength of your documents.

"Alternative energy systems and other things that would make a more environmentally responsible building, things that have higher costs up front but can pay out over the long run, become more possible at this point. We're seeing more folks put in alternative systems that they might not have felt they could afford as add-alternatives for projects," she says. "They can set up their projects to pick and choose a little more. Could they add on solar PV panels? Could they add on a green roof? Can they dedicate more building utilities to saving water, recycling gray water? Can they enhance the building's skin to enhance energy performance?"

Even with energy prices down, it is still cost effective to build green and retrofit buildings for energy efficiency, says Hughes-Doyle. "There's every likelihood that energy rates will go back up. Community colleges that will own and occupy their buildings for the duration still need to look at energy efficiency. Reducing energy consumption by 20-30 percent, which is very, very do-able with current technology, is something districts should definitely be concentrating on."

Whole-Campus Planning

Campuses are also starting to focus on reducing their costs by making sure they're setting up the entire campus to be green. Hughes-Doyle says, "They're delivering more environmentally appropriate landscape, citing, utilities, infrastructure across the campus, so the buildings that are being built can all take advantage of these things collectively. It's a very cost effective way to deliver green across the campus. In other words, the campus in one project can develop a storm water system that percolates storm water back into the ground for a much larger area of the campus, and then other buildings can tap into that system. The farther they push their sustainability master planning to the borders of their campus, the more cost effective it will be to deliver every green building they want to deliver in the future."

That's the plan at LACCD, where the mandate is to build to maximum environmental standards. "We're actually trying to make these new buildings zero-energy," says Eisenberg. "If we make them zero-energy, combined with our other campus-wide renewable energy programs, then they would achieve a Platinum (LEED) rating. At the moment we're not mandating that they be Platinum, but we're trying really hard to make them as environmentally friendly as possible.

At Butte College in Oroville, California, solar projects are providing almost half the electricity needed for the main campus (see sidebar). According to Mike Miller, director of Facilities Planning and Management, the campus green building program is full speed ahead, with two buildings going up at the same time. He's planning for both to qualify for LEED Gold ratings. Replacing portables that have been on the campus for several years, the buildings are numbers five and six of their building program. (See related article )



The Growing Role of Community Colleges

According to the California Community College Chancellors Systems Office (CCCCO), the authority over community colleges in the state, the California community college system is the largest system of higher education in the world. It consists of 72 semi-autonomous districts encompassing 110 colleges, 58 approved off-campus centers and 22 separately reported district offices. Assets include over 20,000 acres of land, 4,629 buildings and 58.5 million gross square feet of space (40.4 million ASF). The system also has many off-campus outreach centers and other facilities. At this point, it serves almost three million students, over seventy percent of the state's public college students.

In 2006, before the recession, before double-digit unemployment statistics and attendant massive demands for retraining of huge swaths of America's workforce, the California Community Colleges Chancellor's Office Facilities Planning and Utilization Unit produced a Five-Year Capital Outlay Plan for new and existing facilities. At that time, the Department of Finance projected enrollment growth of approximately 619,000 higher education students over a ten-year period, with 518,000 expected in the community college system. But as it turns out, this is now a gross underestimate. According to Mike Miller, " At Butte, we've seen 17 percent (enrollment) growth from just a year ago. I know other colleges are experiencing the same spurts. It's unfortunate, but when unemployment goes up, our enrollment goes up."

The five-year plan, covering 2007–2012, called for $11.5 billion of capital facility needs, including $6.4 billion for construction of new facilities and $5.1 billion for modernization of existing facilities. An additional $9 billion was deferred for future years. Along with some other costs, the community college building needs were estimated at about $20.5 billion, which, even then, the CCCCO said was "a conservative estimate...likely to be considerably understated...it is evident that the state's unprecedented postsecondary student growth in the next decade will place a larger burden, relative to the other public postsecondary systems, on the community college system - a burden the CCC system cannot effectively bear without significant new, increased expenditures for facilities."

Those increased expenditures, the report says, include total faculties needs for the next ten years, including the $20.5 billion of capital facility needs identified in the five-year plan, are estimated at $34 billion. Resources currently available are about $14.4 billion, with the remaining to be funded by state general obligation bonds of $19.5 billion. "This equates to a need for $3.9 billion of state general obligation bond funding every two years," the report says.

"The funding for community college facilities is a responsibility shared by the state and local community college districts. The primary source of financing for the local share of construction costs is voter-approved local bonds. Voters traditionally have approved almost all bond measures for education, and at the time of the report, they had approved $14.3 billion in bonds for 54 community college districts.

A Time of Great Change

"Frankly, I think community colleges are the most important public education opportunity to help with this current (economic) downturn in terms of retraining and training, teaching new skills," says Miller. "The jump in enrollment due to the tremendous unemployment rate is something that every community college in California, probably in the nation, is struggling with, because at the same time, we've had massive funding shortfalls.

"We're seeing that a lot of our sister colleges are having to do substantial cutbacks in operations because of these shortfalls. Butte has been fairly fortunate in that we have a conservative board and administration and haven't had to lay anyone off. We're keeping our doors open, and even though we don't know whether or not we're going to get funding to teach all these new students, we're going to try to teach them all, so we're not cutting any programs back. Community colleges, says Miller, "are the stopgap, the safety net for the economy. They are educational institutions that can basically turn on a dime and train where training needs to happen."

Jose Millan, Vice Chancellor of California Community Colleges, says the
the role of community colleges is changing. "Part of the exciting aspect of working at community colleges now is it's actually a time of great change. We see economic changes occurring in our state and our nation, and community colleges are right with those changes. We see this new push for environmental sustainability, as evidenced by the passage of AB32 (California's Global Warming Solutions Act).

“The community colleges are working closely with the Public Utilities Commission, the California Energy Commission and the Air Resources Board to basically implement the provisions of AB 32 by helping businesses comply with those new requirements to reduce greenhouse emissions,” he says. “In order to do that we're developing new programs, training workers, training business owners on the cost benefits of developing this new environmental sensitivity. On the other hand, we are developing new programs, new courses that take advantage of harnessing new renewable sustainable sources of energy for our state. Those energy sources could be solar, wind power, they could be biothermal power, biodiesel power."

In the area of green building, Millan says his office tracks and authorizes all community college building projects, whether the funds are paid for out of local bonds or statewide bonds. "All of it requires some authorization from our office," he says. "We assist the local colleges in getting the necessary approvals for their building projects through the Division of the State Architect."

In addition, the Chancellor's office funds a number of activities related to technological innovation, issuing grants to community colleges for development of new procedures and processes "all in the effort to improve the training and education received by our students so they are more marketable once they leave the community colleges."

The New Green Building Code
With California's green building codes (see related story) coming online, California's community colleges are building for the future. The State Architect, Dave Thorman, has stated that his goal is that after December 2010, all plans coming through the Division of the State Architect (DSA), which approves all community college building plans, will be reviewed for grid neutrality.

According to its newly updated publication, Grid Neutral: Electrical Independence for California Schools and Community Colleges, "Future plans with grid neutral requirements include codifying grid neutral principles into the voluntary 2009 California Green Building Standards Code." While this is not mandatory at this time, the report says, "planning your grid neutral campus now is encouraged because the regulations are right around the corner. The California Green Building Standards Code could be in effect as early as 2012."

Theresa Townsend, senior architect with the DSA, says that " Planning and implementing grid neutral schools now will prepare schools and community colleges for compliance with AB 32. It is estimated that 39 percent of all carbon (CO2) emissions are attributed to buildings," she says. "This includes California’s aging college and school facilities." The law will require that by 2010 the state must begin efforts to offset its carbon emissions from all sources, including educational buildings. By 2020 the state will be required to reduce its CO2 emissions by 30 percent, based on 1990 levels as established by the California Air Resources Board. In 2050 this will be raised to 80 percent.

"This is why we need to find out how much energy our buildings use," says Townsend, "to start work towards more sustainable energy efficient buildings and start producing on-site clean renewable energy. Now is the time to start planning how to go grid neutral and maintain grid neutrality for the long term."

Stimulus Dollars?

There are few potential opportunities for funding of community college building projects from the American Recovery and Reinvestment Act (ARRA), according to Jack Scott, California Community Colleges Chancellor. The CCCCO is a main participant in working out the details of Stimulus allocations to community colleges. In an in-depth memo, he outlines "several pots of Stimulus funding available for community colleges to pursue at statewide and local district or college levels." California will receive about $31 billion in state aid over the next two years. Of this, K-12 and higher education will receive some $7.9 billion, with an additional $6 billion to fund "various labor and workforce developmental activities, of which community colleges are in a strong position to secure a portion of these funds." This funding will be a boon to the instructional and training aspects of community colleges, but according to Scott, the vast majority of funding will not be accessible for building or renovation programs.

"At the moment the Stimulus money in the capital area looks remote," says LACCD's Eisenberg. "It's been going into other areas, not so much higher education facilities. For us, we're not really expecting federal Stimulus money for facilities. We do think that we'll see Stimulus money coming through on the training side in terms of paying for more training and curriculum. If the money comes through from Stimulus for construction, that would be fabulous, but at the moment we're not seeing that as a strong possibility."

Butte College's Mike Miller agrees. "I've been a little frustrated on that level. We don't see direct funding into the California community college system yet. We're exploring those pathways. I'm looking for funding for more energy efficiency projects and also for jobs training. I'd like to get some jobs training money and put people to work right in my facilities department on energy efficiency projects."

Larry Eisenberg things that LACCD is also retrofitting all its existing buildings to maximize energy efficiency. "We can train people to do weatherization types of projects, so there might be some (Stimulus) money coming in on the training side to help out with that," he says.

Test Beds for Innovation

Eisenberg is excited about community colleges and their potential to pilot new technologies. "We're testing innovative products that have remarkable potential for the economy and for the energy industry in general. If these products are successful, they'll be transformational in nature."

He uses an example of LED lighting for offices. "My office is the guinea pig at the moment," he says. "There are things in the energy arena - new energy generation technologies that have really amazing promise on the wind side, on the solar concentrator side - that are very exciting. We want to install them as pilots to test them out and see how they do."

He says colleges traditionally share their information. "A higher tide floats all the boats."

Does the future look bright for community colleges? "It sure does," Eisenberg says.









Copyright © 2008, Green Technology. All rights reserved.


m

The New future of Dabney

http://www.green-technology.org/green_technology_magazine/largest-solar.htm
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--------------------------------------------------------------------------------



Solar array powers Butte College Gymnasium
Photos by Christopher D. Madden for Butte-Glenn Community College District


Butte College aims to be carbon neutral by 2015, and the campus is already well on its way to achieving that goal. It has launched its second-phase solar project of adding four solar arrays that will bring the school to just about 50 percent solar electricity for the main campus. Three of the arrays are complete, already making Butte the largest solar campus in the state. The fourth array will be completed by the end of April.

The district expects to save $32.6 million in energy costs over the next 20 years, since it will pay a fixed energy-use fee and not be subjected to energy price increases. "We're thinking conservatively that energy costs will go up anywhere from eight to ten percent a year," says Mike Miller, director of Facilities Planning and Management for the Butte-Glenn Community College District. "Just since last October we've taken almost a 20 percent increase on our local utility rates."

The completed arrays include 2,400, 185-watt Mitsubishi Electric solar modules mounted on a hillside. The three new arrays total 450 kilowatts in three separate areas of the campus and will produce an estimated 675,000 kilowatt hours of solar electricity and will power 10 campus buildings. Phase one of the project included the installation of 5,700 solar panels on a four-acre field.

Combined, the solar projects' projected energy generation is 2.7 million kilowatt hours each year. Putting it into context, this is enough to power 391 homes and to prevent 1,478 tons of carbon dioxide and tons of other greenhouse emissions from getting into the atmosphere.

Financing for the project was is done through an arrangement with Bank of America. "We should have this paid off in 20 years," says Miller, "on what's called a tax exempt lease purchase, or TELP. We used some bond money as a down payment, and basically our payments are flat over 20 years. At the end of 20 years, the arrays are completely paid for. It's a very good deal for the campus."

The solar projects will not only save the college money and considerably reduce its carbon footprint, they will also serve as teaching tools for students. Chico Electric, the solar installation vendor designed and donated a portion of the solar array to serve as a training lab for students and faculty. At the site, students will install solar panels a into an array, as they would on an actual job site. In addition, Butte College will have an interactive educational kiosk on campus where students will see real-time performance data on the solar system. Butte has just launched a certificate program in sustainability studies, green building courses and green workshops offered on weekends.

Butte College offers a sustainability conference every August focused on green schools, green economy and green energy.










Copyright © 2008, Green Technology. All rights reserved.

The Snow Leopard of our future? Maybe

http://www.tech-recipes.com/rx/4564/snow-leopard-remove-mobileme-isync-menu-bar-icon/
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Snow Leopard – Remove MobileMe / iSync menu bar icon
Contributor Icon Contributed by seamonkey420 Date Icon August 30, 2009
ShareThis Tag Icon Tagged: Apple Mac
Snow Leopard lets one sync his/her own Google contacts and Yahoo contacts to iCal and Address Book. However, a side effect of this is that you will get a Sync Menu Bar item added. For some this is useful, for me its annoying and removing this menu bar item is not as intuitive as one would think. This recipe will explain how to remove the MobileMe / iSync menu bar item.

Lets get rid of that extra menu bar item.

1. Open iSync via Spotlight (command + space bar) or Finder > Applications

2. Go to iSync > Preferences.

3. Uncheck the “Show Status in Menu Bar”. Voila! Sync item removed.

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Name 5 months ago
You can also just hold the command key down and drag icons off the menu bar.
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David Kirk 5 months ago
Great info, Name. Awesome tutorial, SeaMonk. Parallels currently isn't very compatible with Snow Leopard so I have been avoiding updating. It's great to see some Snow Leopard tutorials already...
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Quinn McHenry 5 months ago
I thought it was an old version of parallels.. 2.5 maybe? I think that might be the version that would let you run Win 3.1. This is all hypothetical, anyway because... Windows? Really? :-P
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David Kirk 5 months ago
Windows kidding aside... only parallels 4.0 will run with Snow Leopard. Even it won't run in 64-bit mode. To get a stable parallels install you have to boot snow leopard in 32-bit mode. :(
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David Kirk 5 months ago
Actually, I just checked and parallels has released a new build to cover a lot of the snow leopard problems... so maybe I can finally update. woot woot! :)
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seamonkey420 5 months ago
nice! i was wondering when they would get a snow leopard build ready.
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billy_Bob_123994 5 months ago
Or you can just do CMD ALT click and drag it off the bar.
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alan 4 months ago
or you can CMD click and drag it off the bar :-)
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Jay 4 months ago
Appreciate the info!
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The Snow leopard is an endangered species. Will this be the Snow leopard of the future?