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BGP to BGP Redistribution

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

1 ACCEPTED SOLUTION

Accepted Solutions
Gold

BGP to BGP Redistribution

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.

Hope it Helps!

Soroush.
3 REPLIES
Gold

BGP to BGP Redistribution

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.

Hope it Helps!

Soroush.
New Member

BGP to BGP Redistribution

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

Gold

BGP to BGP Redistribution

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.

Hope it Helps!

Soroush.
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