06-27-2012 12:37 PM - edited 03-04-2019 04:49 PM
Hi everyone,
router bgp 5
neighbor 1.1.1.1 remote-as 50
neighbor 1.1.1.1 default-originate
neighbor 2.2.2.2 remote-as 500
neighbor 2.2.2.2 local-as 65011
neighbor 2.2.2.2 default-originate
neighbor 2.2.2.2 allowas-in 2
neighbor 2.2.2.2 soft-reconfiguration inbound
neighbor 2.2.2.2 route-map SET_WEIGHT in
no auto-summary
In above configuration, router is doing bgp neighboeship with 1.1.1.1 which is ISP-1. neighbor 2.2.2.2 is not configured yet. I have just these commands created in notepad. My company they want to bring ISP-2 up which is 2.2.2.2 and after few months they are planning to remove ISP-1. So my question is when router will have both BGP neighbor, will routes are forwarded from one neighbor to another? also is it possible to redistribute routes ? Both ISPs are running MPLS for our PIP.
Thanks
Solved! Go to Solution.
06-27-2012 02:21 PM
it doesnt matter how many routers u have involved in your bgp process, as far as you are running a bgp (AS), if the isp doesnt filter routes for/to ur side, the updates that you receive through bgp from ur eBGP peers will be advertised to the other BGP peers.
what you are saying regarding to BGP and IGP n redistribution is wrong, that is when you want to get a Local or Static route to be advertised into BGP, not the already BGP prefixes that came in from the other ISP.
in order to avoid the risk of being a transit AS and to advertise your Local routes to ur eBGP peers, do this:
ip as-path access list 20 permit ^$
route-map LOCAL permit 10
match as-path 20
router bgp 5
neighbor 1.1.1.1 route-map LOCAL out
neighbor 2.2.2.2 route-map LOCAL out
plz Rate if it helped,
Soroush.
06-27-2012 01:43 PM
Hi,
Yes, if you peer with two ISP (ASes), normally you would become a Transit AS and re-advertise routes from one ISP into another. although you can eliminate this by using route-maps.
i didnt get what you mean by redistribute routes? could u elaborate?
HTH
plz Rate if it helped,
Soroush.
06-27-2012 02:07 PM
Hi soroushm,
Thanks for reply. Here both neighborship is from the same router. So if I dont add routes from one ISP into IGP, how another BGP neighbor will learn them without network command or redistribution ? So what I understand is if I dont redistribute BGP routes into IGP than my AS will not become transit AS.
Thanks
06-27-2012 02:21 PM
it doesnt matter how many routers u have involved in your bgp process, as far as you are running a bgp (AS), if the isp doesnt filter routes for/to ur side, the updates that you receive through bgp from ur eBGP peers will be advertised to the other BGP peers.
what you are saying regarding to BGP and IGP n redistribution is wrong, that is when you want to get a Local or Static route to be advertised into BGP, not the already BGP prefixes that came in from the other ISP.
in order to avoid the risk of being a transit AS and to advertise your Local routes to ur eBGP peers, do this:
ip as-path access list 20 permit ^$
route-map LOCAL permit 10
match as-path 20
router bgp 5
neighbor 1.1.1.1 route-map LOCAL out
neighbor 2.2.2.2 route-map LOCAL out
plz Rate if it helped,
Soroush.
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