From: Leigh Harrison (ccileigh@gmail.com)
Date: Fri Nov 11 2005 - 11:45:39 GMT-3
Hey chap,
It depends on the layout of your lab and the rules you're playing by.
If you've got bgp neighbours next to eachother in the same AS, then:
router bgp 1234
neigh 1.2.3.4 remote-as 1234
If it's a different as:-
router bgp 1234
neigh .1.2.3.4 remote-as 4321
If they are not next to eachother (different AS), then you'll need to add:-
neigh 1.2.3.4 ebgp-multi-hop
If you're not allowed to pass the routes through an igp and your router
doesn't know how to get there, then add:-
neigh 1.2.3.4 next-hop-self
The train of though goes:-
If you can see him to peer with him (remember bgp peering uses tcp),
then you must be able to route to him.
It took me one very long night and a lot of coffee to grasp this one.
One of my routers in bgp did not have a route to the next hop and
wouldn't do a thing with the routes. When I *eventually* put in
next-hop-self (on the advertising router), it sent it to the router that
gave him the routes.
Have a crack at a combination of the above. If I'm miles away, then
post some of the question and I'll see if I can't be more specific.
LH
dusth@comcast.net wrote:
>Hi Leigh, Yes, you are right. I can make the tunnel up and BGP traverse inside the tunnel if I give tunnel ip address and using tunnel ip address for peering. However, usually additional ip address and floating static route are not allowed and if I can not redistribute BGP into IGP:) What would be the better solution? Dustin
>
>-------------- Original message --------------
>
>
>
>>Quick note - if you do put that route in, the tunnel will collapse...
>>As it'll think the destination of the tunnel is down the tunnel...
>>
>>Give the tunnel an ip address and peer with that as a test.
>>
>>LH
>>
>>Godswill Oletu wrote:
>>
>>
>>
>>>Dustine,
>>>
>>>nei 4.4.4.4 update-source loopback0
>>>
>>>Tell this router that, when it is negotiating bgp session with neighbor
>>>4.4.4.4, it should present the ip address on interface loopback0 as its
>>>source address.
>>>
>>>If you debug bgp on this router or on the remote router, you will discover
>>>that this router is actually using the ip address of loopback0 as its source
>>>address.
>>>
>>>But for this router to reach neighbor 4.4.4.4, it will go to your IGP
>>>routing table and pick the next hop address to reach 4.4.4.4 and will send
>>>the traffic to neighbor 4.4.4.4 through the next hop address in your
>>>routing table. If that next hop address is through the tunnel14, then the
>>>traffic will go through the tunnel14 interface.
>>>
>>>So, the answer to your question will a No.
>>>
>>>But if you do "ip route 4.4.4.4 255.255.255.255 tunnel 14'
>>>
>>>Then, bgp traffic will attempt to reach neighbor 4.4.4.4 via tunnel 14.
>>>
>>>HTH
>>>Godswill Oletu
>>>
>>>
>>>----- Original Message -----
>>>From:
>>>To:
>>>Sent: Thursday, November 10, 2005 7:05 PM
>>>Subject: BGP and Tunnel
>>>
>>>
>>>
>>>
>>>
>>>
>>>>Hi all, I need some clarification on how does bgp know to traverse inside
>>>>
>>>>
>>>>
>>>>
>>>the tunnel and what parameter of the tunnel interface tell that for bgp end
>>>points? I do not have access to the lab right now so I can not verify the
>>>config.
>>>
>>>
>>>
>>>
>>>>Here is the example:
>>>>r1:
>>>>interface tunnel 14
>>>>ip unnumber loopback 0
>>>>tunnel source 1.1.1.1
>>>>tunnel destination 4.4.4.4
>>>>bgp 10
>>>>nei 4.4.4.4 remote-as 10
>>>>nei 4.4.4.4 update-source loopback0
>>>>Does the ip unnumber of the tunnel or the tunnel source & destination tell
>>>>
>>>>
>>>>
>>>>
>>>router that bgp traffic need to traverse inside the tunnel?
>>>
>>>
>>>
>>>
>>>>Thanks in advance,
>>>>Dustin
>>>>
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>>>>
>>>>
>>>>
>>>>
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>
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