untangling_the_web

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in theory reachable by and from any other point on the Internet. But at the same
time, every network most certainly is not connected directly to every other network
on the Internet, so there had to be accommodations made to ensure that traffic could
flow freely around the globe. This mutually beneficial arrangement to exchange
Internet data freely between two networks is a peering agreement. I'll accept and
forward your traffic if you'll accept and forward mine.
CIDR
One final concept needs to be mentioned. About a decade ago people realized that
something had to be done about Internet addressing. There were real concerns that
we would run out of IP addresses and run out of capacity in global routing tables,
with new networks being connected to the Internet at the rate of about one every
thirty minutes. The solution was something called CIDR (pronounced "cider").
CIDR "CIDR stands for Classless Inter-Domain Routing ... CIDR is an effective
method to stem the tide of IP address allocation as well as routing table overflow.
Without CIDR having been implemented in 1994 & 1995, the Internet would not be
functioning today. Basically, CIDR eliminates the concept of class A, B, and C
networks and replaces this with a generalized 'IP prefix,.,,149 CIDR permits blocks of
addresses to be assigned to networks as small as 32 hosts or as large as those with
over a half a million hosts. This type of address assignment more accurately reflects
an organization's actual size and specific network requirements .
What is the relationship between CIDR and the Autonomous System? Perhaps the
easiest way to understand their relationship is to think of "an Autonomous System as
a collection of CIDR IP address prefixes under common technical management. For
example, the CIDR block from 208.130.28.0 to 208.130.31.255, as well as network
201.64.75.0 might be AS2934. n150 In turn, AS2934 may represent one network made
up of 50 computers or fifty networks made up of thousands of computers.
149 The CIDR FAQ, version 7.0, May 2004, (14 November 2006).
150 "Autonomous System ," Connected : An Internet Encyclopedia, Third Edition , April 1997,
(14 November 2006).
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