Bgp Peering with Loopbacks

[mike987]

I have always used the loopback address in my bgp peering.

router(config-router)#neighbor 10.10.10.1 remote 43578
router(config-router)#neighbor 10.10.10.1 up lo0
router(config-router)#neighbor 10.10.10.1 eb

I have been using the Internetwork Experts workbooks, and all of their solutions use the link address.

router(config-router)#neighbor 123.45.678.9 remote 43578

I know it is less entries, but the loopback address is a habit. What is the recommended (lab) way to do it? Since it doesn’t seem to be specified anywhere which way to use, I am assuming that my way is ok. Unless of course it says something like "Use the least amount to BGP Neighbor statements to complete this task" then I guess the link address would be the best way

Any one know which way I should be doing this?

[lazypo]

It's up to you, your talking about ibgp peering i take it.The loopback address wil just give you added
redundacy incase the physical port failed and you had alternative routes to the peer.It's not really about being right or wrong its a design issue.

[mike987]

No. I use it like that when i am using EBGP also. I just add the EBGP Multihop command and it works fine. That is not wrong is it?

[lazypo]

It will work of course,but i would say it is wrong, if i was marking the lab i would assume you didnt fully understand the concept.Your ebgp peer is directly connected so if you lose the physical link you lose the peer, so you're better to use the ip address on the link.
With the multihop you could maintain an ebgp through another ebgp peer but it wouldnt serve any purpose and could create a mess.

[tagteam]

I agree with lazypo, IBGP loopback peering is often done with loopbacks, which is fine because you usually have an IGP running or something to make the loopbacks reachable because its your AS. However if your running EBGP you'll have to mess around making loopback addresses reachable first before advertising and in the real world you probably won't be running an additional IGP between EBGP peers. But for the lab exam itself I have come across questions where it says "create an EBGP connection between R1 and R2s loopback interfaces" in which case you have to choice other than to use multihop/next hop self, and static routes for the loopbacks.