From: rsevier (rsevier@xxxxxxxxxxxxxxxxxxx)
Date: Tue May 22 2001 - 12:35:21 GMT-3
Matt is correct. Below is a sample config. Check it carefully because I
put it together quickly. Notice as-path 3, that is there to not have
packets coming from williams to have to out their network to come in L3's
connection. this will allow the williams packets to come in through the
william's connection and not to touch L3's network at all.
matt- say hi to Ken Walls and Eddie for me.
neighbor x.x.x.x remote-as 3356
neighbor x.x.x.x version 4
neighbor x.x.x.x route-map from-willims in
neighbor x.x.x.x route-map TO-williams out
neighbor x.x.x.x remote-as 3356
neighbor x.x.x.x version 4
neighbor x.x.x.x route-map from-willims in
neighbor x.x.x.x route-map TO-williams out
neighbor x.x.x.x remote-as (william's AS)
neighbor x.x.x.x ebgp-multihop 2
neighbor x.x.x.x update-source Loopback0
neighbor x.x.x.x version 4
neighbor x.x.x.x route-map from-L3 in
neighbor x.x.x.x filter-list 10 out
ip as-path access-list 1 permit .*
ip as-path access-list 2 permit ^$
ip as-path access-list 3 permit ^(williams AS)$
ip as-path access-list 10 permit ^$
route-map from-L3 permit 10
match as-path 1
set local-preference 150
!
route-map from-williams permit 10
match as-path 3
set local-preference 160
!
route-map from-williams permit 20
!
route-map TO-willaims permit 10
match as-path 2
set as-path prepend 3356 3356 3356 3356 3356 3356 3356 3356
Raymond
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Matt.Wilkerson@Level3.com
Sent: Tuesday, May 22, 2001 7:41 AM
To: oriya@techiesclub.com
Cc: ccielab@groupstudy.com
Subject: RE: BGP Question
Finally... 1 I can contribute on :>)
You need to use a route-map on your bgp "neighbor x.x.x.x" statements. There
are 2 directions of traffic you need to influence, your inbound traffic and
your outbound traffic. This can most easily be done by adjusting the "as
path" and the "local pref" attributes.
On the outbound route-map, you'll need a "match" statement which will permit
any, followed by a set statement, which will prepend your AS a couple times
on the Williams link. This will make your williams link appear to have a
longer route, than the Level3 path. Which will shift your incoming traffic
to the Level3 link.
ex. L3- 3356-YourAS
Williams 5555-YourAS-YourAS-YourAS-YourAS
<----this appears a longer route
To affect your outbound traffic, you'll need to tag the Level3 link with a
higher "local-pref" See the short examples below...
#######################################
route-map Williams-Outbound-Map permit 10
match ip address 1 <---------references access list 1
set as-path prepend 3356 3356 3356
route-map Level3-Inbound-Map permit 10
match ip address 1 <--------Same here
set local-preference 200
access-list 1 permit any
router bgp YourAS
neighbor 1.1.1.1 route-map Williams-Outbound-Map out
neighbor 2.2.2.2 route-map Level3-Inbound-Map in
######################################
-----Original Message-----
From: Oriya Pollak [mailto:oriya@techiesclub.com]
Sent: Tuesday, May 22, 2001 11:09 AM
To: ccielab
Subject: BGP Question
Let me ask you all a question.
I have BGP running between our router to our 2 Internet uplinks - Level3
Communications and Williams Communications. I would like to push almost no
traffic or not at all to Williams but I do want to have it up in case level3
goes out and traffic needs to go on Williams.
Any ideas?
Oriya
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