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BGP over GRE tunnel----VOl1

====================================================================

R2  ------------------CORE----------------------R6
f0/0                                                            f0/0 
155.1.23.2                                            155.1.146.6

====================================================

R2 is advertising 222.22.2.0/30 in BGP and R6 is advt 118.0.0.0/30 in BGP.
No BGP in the core and no redistributaion is allowed from BGP to IGP in core.

Requriment :- R2 should ping to 118.0.0.0/30 with source as LOOPBACK IP
and R6 should ping to 222.22.2.0/30 with source as LOOPBACK IP

-----

On R2

-----

Int tu 0
Ip address 10.10.10.1/24
tunnel src 155.1.23.2
tunnel dest 155.1.146.6

router BGP 200
nei 155.1.146.6 remote-as 100
nei 155.1.146.6 route-map fromR4 in
net 150.1.2.2 mask 255.255.255.255 <----Advt loopback in BGP


route-map fromR4
set ip next hop 10.10.10.2

-------

On R6

-------

Int tu 0
Ip address 10.10.10.2/24
tunnel src 155.1.146.6
tunnel dest 155.1.23.2

router BGP 100
nei 155.1.23.2 remote-as 200
nei 155.1.23.2 route-map fromR4 in
net 150.1.6.6 mask 255.255.255.255 <----Advt loopback in BGP

route-map fromR4
set ip next hop 10.10.10.1

I have done the above mentioned configuration(With BGP multihop) and everthing is working fine(Tunnel are UP)

However if i change the nexthop on R2 to 10.10.10.1 and on R6 to 10.10.10.2 its not working.

As per my understanding its should work as by setting up the next hop to 10.10.10.1 i am forcing traffic via tunnel.

Please help to find the resaon behind this.

5 REPLIES
VIP Super Bronze

BGP over GRE tunnel----VOl1

Hi,

Do you have a static route on r2 to reach 10.10.10.2 and on r6 to reach 10.10.10.1?

Can you reach 10.10.10.1 and  10.10.10.2 from the each router?

HTH

BGP over GRE tunnel----VOl1

Hi Ganpat,

as your Tunnel interfaces will remain up no matter BGP is working or not, why don't you change the BGP neighbor as the tunnel interface ip of the peer i.e for R2:

router BGP 200

nei 10.10.10.2 remote-as 100

And for R6:

router BGP 100

nei 10.10.10.1 remote-as 200

This might accomplish what you are looking for and you wouldn't have to change the next-hop using that route-map either

HTH

Neeraj

New Member

BGP over GRE tunnel----VOl1

Hi Neeraj,

Configuring BGP on tunnel is the one option.However in the task that option is not permitted so i have to use next hop change option.

What i am looking is ....If i set ip next hop 10.10.10.2 on R2,then R2 is sending the traffic via tunnel.

Then why R2 is not forwording the traffic by tunnel if i set ip next hop 10.10.10.1. ?

/Ganpat

New Member

BGP over GRE tunnel----VOl1

This issue might no longer exist, but for the sake of others who might have the same questio;,

The config seems fine. It is possible that the BGP session between R2 and R6 needs to be cleared in order to reflect the new next-hop information.

The command to do so is #clear ip BGP [in|out]

Verify that the next-hop shows up in the BGP table as the tunnel interface addresses and you should be good to go.

Cheers

#saxotob

Bronze

BGP over GRE tunnel----VOl1

It wasn't specifcally mentioned, but since it's an eBGP connection, you'd need "ebgp-multihop" to establish the session. 

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