Vain moment of my life..
Friday, August 01, 2008
Memory Gap
Tsk tsk need to refresh again... my boss pops a question about ip segment awhile ago and i couldn't answer him!! and I realizedI forgot-it already that's why I tried to browse site such as http://www.cisco.net/ and even http://www.google.com/ but I hardly find anything close to ip segment or whatever-that-is-for- goodness-sake. A screaming I COULDN'T FIND IT! was written all over my face while scratching my head infront of my monitor. I finished CCNA pa naman up to it's module 4 and so shame of me na hindi ko nasagot yung question anyway that was since 2002 pa naman when I took it (defending myself?) and mind you I didn't took the licensing exam why? all of my classmates backed out no one to share it with if i passed it hmm.. well that's what my childish opinion then, I wasn't techy that time.I tried calling my former professor (call a friend?) but he's not there sa school anymore he resigned already omg! i can't believe-it..Mr. Leo Lobramonte the Technical Director the cisco expert and blah..blah..blah.. wasn't there anymore? well so much of me to care and because I'm helpless all I can do is to just rebrowse info about IP address and subnetting na lang it might help to refresh my memory( poor me*#!) memory gap tsk tsk..
What Are IP Addresses and How Are They Used?
IP (Internet Protocol) addresses are used to identify hosts on the campus Internet, a Cornell network that ties into the Internet, a global network. If the computer is attached to Cornell's network, it needs an IP address to be recognized as part of the campus Internet.
IP addresses are constructed according to a set of specific rules so that hosts on any part of the Internet can communicate with each other. This document describes IP addresses only as they apply to Cornell's campus network. (If you want to know more about Internet addressing, refer to Internetworking with TCP/IP: Principles, Protocols, and Architecture by Douglas Comer, Prentice Hall).
An IP address consists of a 32-bit binary number, which is typically presented as four decimal numbers (one for each 8-bit byte) separated by decimal points. For example, 128.253.21.58.
Internet addresses at Cornell have three parts:
What Are IP Addresses and How Are They Used?
IP (Internet Protocol) addresses are used to identify hosts on the campus Internet, a Cornell network that ties into the Internet, a global network. If the computer is attached to Cornell's network, it needs an IP address to be recognized as part of the campus Internet.
IP addresses are constructed according to a set of specific rules so that hosts on any part of the Internet can communicate with each other. This document describes IP addresses only as they apply to Cornell's campus network. (If you want to know more about Internet addressing, refer to Internetworking with TCP/IP: Principles, Protocols, and Architecture by Douglas Comer, Prentice Hall).
An IP address consists of a 32-bit binary number, which is typically presented as four decimal numbers (one for each 8-bit byte) separated by decimal points. For example, 128.253.21.58.
Internet addresses at Cornell have three parts:
Network Address
Cornell has four addresses for its backbone networks. They are 128.253.0.0, 128.84.0.0, 132.236.0.0, and 140.251.0.0. The latter is used only by the Cornell University College. These addresses are assigned to Cornell. Cornell cannot change the first two parts of each address, but is free to use the last two parts in any way it chooses in order to identify Local Area Networks (subnets) and hosts that are connected to the campus Internet.
Subnet Address
The subnet address is the address given to your Local Area Network (LAN). Cornell's system provides for 254 LANs connected to each of the main networks. So, for example, if your LAN is identified on the network as 128.253.0.0, a possible subnet addresses (or LAN address) might be 128.253.21.0. The third number, 21, identifies the subnet.
Host Address
The host address is the address given to the workstation, other computer, or device that is connected to the LAN. Cornell's system provides for 256 host addresses on each LAN. So, for example, if your host is identified on the LAN as 128.253.21.0 a possible host address is 128.253.21.58. The last number, 58, identifies the host.
Not all 256 numbers are available as host addresses on any given LAN. Zero (0) and 255 are reserved for broadcast purposes. (Hosts are set up to "grab" any message marked with their own address or a broadcast address; for example, if your host address is 128.253.21.58 and it "sees" a message addressed to 128.253.21.255, it will grab the message. In this way, hosts can send messages to large groups without having to know each address on their LAN.)
One (1) is reserved for the gateway/router that sits between the LAN and next network level. The numbers 2-5 are reserved by CIT for diagnostic and management use.
IP Addressing Space
This addressing scheme has worked well for Cornell, but it has some limitations:
Each of Cornell's fiber backbones can have no more than 256 LANs attached to them.
Each LAN can have no more than 256 (249 if reserved addresses are taken into account) hosts. Most LANs are constructed with far fewer than the maximum number of hosts addresses available.
Ethernet LANs performance is reduced with a large number (100 or more) of connections. Performance is most affected by how people are using the LAN: a small number of heavy users can bog down the performance of any LAN. Therefore, the limitations on the number of host addresses hasn't been and isn't expected to be a problem for most LANs at Cornell.
To make room for additional subnet addresses, or LANs, CIT has used a system called sub-subnetting. With this system, up to four LANs can use one full subnet address, thus effectively quadrupling the number of subnet addresses available.
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