From: Jason Madsen (madsen.jason@gmail.com)
Date: Mon Dec 29 2008 - 18:44:17 ARST
Hi Atul,
It appears you answered your own question...or at least the answer to your
question was in your email. *_100$* defines / matches any routes that were
orginated / advertised in AS 100 (e.g. 300 200 100). *^100.** defines /
matches routes that passed through AS 100 to yours (e.g. 100 200 300); AS
100 is directly connected to yours. Actually, because of the *.* *It
would be any directly connected AS that begins with the number 100 e.g.
1000, 1001, 1002, 100.
*show ip bgp *will show you what routes, if any, you're learning via BGP.
It will also show you what AS the routes were originated in and traversed
through to get to your AS. The AS number listed all the way to the right is
the originating AS (xxx$). The AS all the way to the left is the neighbor
AS that your AS is connected to and is receiving routes from (^xxx).
Try setting up a BGP scenario in which you have multiple AS's, advertise
routes in each of them, and then do a show ip bgp and also play around with
various show ip bgp regex xxx commands, where "xxx" is replaced with a
regular expression. There are at least a couple of places in the Doc CD
that discuss regex. Here are a couple:
IOS --> 12.4 --> Terminal Services --> Appendixes --> Regular Expressions
IOS --> 12.4 --> Config Fundamentals --> Understanding the CLI --> Regular
Expressions
Jason
On Mon, Dec 29, 2008 at 1:09 PM, ccie preparation <ccie22@gmail.com> wrote:
> Folks,
> Can someone tell me the difference between the two.
>
> _100$This expression indicates an origin of AS100.
>
> ^100 .*This expression indicates transmission from AS100.
>
> Thanks,
> Atul
>
>
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