nanog mailing list archives

Re: IPv6: numbering of point-to-point-links


From: Gary Buhrmaster <gary.buhrmaster () gmail com>
Date: Mon, 31 Jan 2011 13:52:19 -0800

On Mon, Jan 31, 2011 at 09:13, Blake Hudson <blake () ispn net> wrote:
....
I setup a p2p /127 link and found that BGP would not peer over the link;
Changing to /126 resolved the problem. I never looked into it further
because I had intended to use /126 from the start. My guess is that
while BGP should be a unicast IP, Cisco's implementation uses an anycast
in some cases, disregarding the configured unicast address.

Just one practical example...

I suspect this is very platform/version specific, as I have run BGP
on a Cisco 6500 (SXI<mumble>) to a Juniper MX and we had no
trouble with a /127 (although prepared to move to a /126 or whatever
if needed).  As always, your environment will vary.  I would open
a TAC case on the principal that it should work.


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