Re: [Idr] draft-walton-bgp-hostname-capability-00

["Rajiv Asati (rajiva)" <[e-mail]>]

If it is about figuring out the adjacent IPv6 neighbor names (certainly, a reasonable operational ask), then let's not solve it just for BGP (or using BGP), else we would end up solving the same problem again (using a different protocol) for non-BGP enabled nodes.

Perhaps, IPv6 ND (*) is better suited to carry the host names. The reason is that IPv6 ND is mandatory for every IPv6 node, hence the lowest common denominator.

BGP can pick up the host names from the local ND database and display it in the neighbor table.

Of course, this doesn't solve the multi-hop BGP scenario, but IPv6 LL addresses (the original intent of this draft) can't be used in multi-hop anyway. It also doesn't solve the BGP path trace (that Robert pointed out).

We should bring this up to the v6ops and IPv6 groups.

Cheers,
Rajiv


Ps:

On May 16, 2015, at 6:27 AM, Robert Raszuk <[e-mail]<mailto:[e-mail]>> wrote:

Dinesh,

Q1 - how do you ping physical interface not a loopback

In the DC, common practice I've seen is pinging node, not physical interface. The physical interface addresses aren't even advertised to be able to be reachable more than one hop away.

​Ping is just an example. Think about tool like BGP path trace ... do you want to know the interface names packets are coming on from leaf to leaf or not ? I was hoping with your extension you will be providing node name of the form spine44_g10 (where eth10 is the interface ​name).


Q2 - how about lookup on bgp rtr id instead LL address to get the name ?

I don't lookup LL address. Router ID is typically the loopback IP address in DC,

Perhaps you missed my point. If router id is loopback as you correctly point out you already have it during BGP OPEN msg on any peering session so just reverse DNS lookup on router_id will provide you with the name of the node. Done with no bgp extensions needed.

If DNS is down as Thomas points out your names are useless for troubleshooting anyway so you fall back to using old fashined IP addresses in the show command :)

- - -

Now since we are on this topic we had an idea long long time back to carry the name of the next hop in BGP (learned from ISIS extension which Henk did) so not only peering will be known locally, but you can also see next hops by node names rather then IPv6 like strings.

Originally it was added to IGP extensions for BGP discovery.

later the proposal was to carry this as new next hop descriptor attribute so everynode in the AS can use it.

Now we are working on BGP remote next hop draft which could be used for that as well. It will apply both to EBGP DC cases as well as for the normal IBGP AS. In DC normally nh = peering address so naturally your case would also be solved.

Using capability you only know the name of your immediate peer and that sounds like a bit of limitation to me.

Propagating the name in the update as an attribute or new wide bgp community (which I am happy to add new type for) seems to like a much better option especially if other proposals already call for introduction of beacon prefixes.

Best,
r.

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