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New Member

BGP command nei next hop self between IBG neighbours

Hi all,

I have this BGP setup

R1 -----------R2 ---------------R3----------------------------R4

R3 and R4 are EBGP neighbours.

R1,R2 and R3 are in same AS  and are IBGP neighbours.

As we know that R2 will not advertise the routes learned from R3  to R1

so i have config this on R2

neighbor 100.100.100.100 route-reflector-client

R1 loopback 100.100.100.100

R2 loopback 2.2.2.2

R3 loopback 6.6.6.6

When i config the command on R2 below one

neighbour 100.100.100.100 next hop self

Now i do the sh ip bgp on  R1

R1  does not show next hop as 2.2.2.2 it shows next hop as R3 loopback address which is 6.6.6.6

I need to know why next hop self does not change the next hop on R1?

Thanks

Mahesh

  • LAN Switching and Routing
2 ACCEPTED SOLUTIONS

Accepted Solutions

Re: BGP command nei next hop self between IBG neighbours

As far as I understood 100.100.100.100 is R1 ip.

R2 is the RR.

R2

route-map reflector

set ip next-hop 2.2.2.2

if 2.2.2.2 is the ip with whom R1 establish it's adjacency

router bgp 6500

nei 100.100.100.100 route-map reflector out

end

clear ip bgp * soft

Dan

Re: BGP command nei next hop self between IBG neighbours

It applies all the rules configured on route-map to all prefixes advertise to that neighbor.

In your case , it will change the next-hop of all routes advertised to R1.

Here is a link , for futher reading :

http://wiki.nil.com/BGP_route_reflectors

"The next-hop-self neighbor configuration parameter or (most of the) set options of outbound  route-map configured on route-reflector clients are ignored for reflected routes. BGP next-hop can be changed set ip next-hop route map command ( BGP next hop propagation feature introduced in IOS release 12.2)"

Dan

10 REPLIES

Re: BGP command nei next hop self between IBG neighbours

Mahesh,

Did you try clearing the peering between R2 and R1? You should be able to do a soft reset.

John

HTH, John *** Please rate all useful posts ***

Re: BGP command nei next hop self between IBG neighbours

Hi Mahesh ,

You cannot change the next-hop of the route with "next-hop self"  on a RR to a route-reflector client

If you want to change it you must use a route-map and set ip next-hop , and apply the route on the out of the neighbour.

Dan

New Member

BGP command nei next hop self between IBG neighbours

Hi Dan,

Thanks for reply.

You mean that on R2 router i can config this

router bgp 6500

route-map reflector

set ip next-hop 100.100.100.100

Let me know if this is right way?

Thanks

Mahesh

Re: BGP command nei next hop self between IBG neighbours

As far as I understood 100.100.100.100 is R1 ip.

R2 is the RR.

R2

route-map reflector

set ip next-hop 2.2.2.2

if 2.2.2.2 is the ip with whom R1 establish it's adjacency

router bgp 6500

nei 100.100.100.100 route-map reflector out

end

clear ip bgp * soft

Dan

Re: BGP command nei next hop self between IBG neighbours

By tthe way when you are setting the next-hop as it's own IP , you will get an warning. Do not worry about it

Dan

New Member

BGP command nei next hop self between IBG neighbours

Hi Dan,

It worked fine now.

So just last thing what does command  nei 100.100.100.100 route-map reflector out do?

Thanks

Mahesh

Re: BGP command nei next hop self between IBG neighbours

It applies all the rules configured on route-map to all prefixes advertise to that neighbor.

In your case , it will change the next-hop of all routes advertised to R1.

Here is a link , for futher reading :

http://wiki.nil.com/BGP_route_reflectors

"The next-hop-self neighbor configuration parameter or (most of the) set options of outbound  route-map configured on route-reflector clients are ignored for reflected routes. BGP next-hop can be changed set ip next-hop route map command ( BGP next hop propagation feature introduced in IOS release 12.2)"

Dan

New Member

BGP command nei next hop self between IBG neighbours

Hi Dan,

Many thanks for reply back.

Regards

Mahesh

BGP command nei next hop self between IBG neighbours

My pleasure , Mahnesh.

Dan

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