From: mgreenlee@ipexpert.com
Date: Mon Nov 19 2007 - 10:14:12 ART
Seriously, before posting you should start with one of the following:
1. Read the command reference
2. Lab up with a few routers
3. Search the archives
Regarding Local AS:
Local AS allows a router to basically "pretend" to be in a different AS for
a specific peering.
R1(AS1)---R2(AS2)
On R1, if "local-as 3" was configured for the neighbor statement to R2, R2's
peering would be to AS 3 for R1, not to AS1.
Regarding the 'no-prepend':
...'no-prepend' prevents the 'local-as' AS from being added to the path, but
only for peerings "behind" the 'local-as' peering. From the outside, you
will always see the
'local-as'.****R1(AS1)--R2(AS23)--R3(AS23)--R4(AS4)--R5(AS5)Network XX on
R1, Network YY on R5.Assuming that R3's peering to R4 includes local-as
100R1(AS1)--R2(AS23)--R3(AS23)--local-AS100))-R4(AS4)--R5(AS5)R1 sees
network YY with path 23 100 4 5.with no-prepend on R3's peering to R4, R1
would see 234 5.R5 sees network XX with path 4 100 23 1.with no-prepend on
R3's peering to R4, R5 still sees the path as 4 100 23 1.****In this case,
R1 and R2 are "behind the 'local-as'",and may or not see the local-as in the
path depending on whether or not the no-prepend keyword is used. R4and R5
are "outside the 'local-as'", and will always see local-as, regardless of
whether or not R3 is configured with the 'no-prepend' keyword.
Marvin Greenlee, CCIE #12237 (R&S, SP, Sec) Senior Technical Instructor -
IPexpert, Inc.
A Cisco Learning Partner - We Accept Learning Credits!
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
Mailto: mgreenlee@ipexpert.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
itsfortarget@gmail.com
Sent: Monday, November 19, 2007 2:03 AM
To: ccielab@groupstudy.com
Subject: LOCAL AS
hello,
What is the need of LOCAL-AS command with BGP neighbour Command and watht is
the significant of LOCAL-AS No prepend
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