ASes
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... Autonomous System (AS), and lists criteria for such. ASes are the
unit of routing policy in the modern world of exterior routing ...
... routing
protocols and will be someone who configures and operates Internet
networks. Unfortunately, there is a great deal of confusion in how
ASes should be used today; this memo attempts to clear up some of
this confusion, as well as acting as a simple guide to today's
exterior routing ...
... using an exterior gateway protocol to route packets to other ASes.
Since this classic definition was developed, it has become common
for a single AS ...
... IGPs and metrics are used, the administration of an AS
appears to other ASes to have a single coherent interior routing
plan and presents a consistent picture of what networks ...
... Internet today. It is the exchange of routing information
between ASes that is subject to routing policies. Consider the case
...
... subject to routing policies. Consider the case
of two ASes, X and Y exchanging routing information:
...
... in both the exchange of exterior routing information (between
neighboring ASes), and as an identifier of the AS itself.
...
... Common errors in allocating ASes ...
... does not need to be unique unless routing information is indeed
exchanged with other ASes. See "IGP Issues".
...
... AS must be used for exchanging external routing information
with other ASes through an exterior routing protocol. The cur-
rent recommended exterior routing protocol ...
... prefixes should be part of a
single AS, distinct from the ASes of its service providers.
This allows the customer ...
... AS number application forms have historically made no reference
to routing policy. All too often ASes have been created purely
because it was seen as "part of the process" of connecting to
...
... up an AS or a prefix into two ASes for policy reasons. Those making
external policy may request the network operators make such AS ...
... network operators
who manage the prefixes in question, as well as the ASes containing
them. This is, of course, a trade off -- it will not always be
possible to implement all desired routing policies ...
... prefix which is used in neighbor peering
between two ASes, a conscious decision should be made as to which AS
this prefix ...
... integer and hence limited to 65535
unique AS numbers. At the time of writing some 5,100 ASes have been
allocated and a little under 600 ASes are actively routed in the
...
... AS numbers. At the time of writing some 5,100 ASes have been
allocated and a little under 600 ASes are actively routed in the
global Internet. It is clear that this growth needs to be continually
...
...
There are few security concerns regarding the selection of ASes.
...