Nick, if I may ask, since I've nt used XR yet, are the prefix-sets you
detailed like the ios prefix-lists?
Your way of expressing the filter seems much more spiffy than the old
ip prefix-list internal only seq 5 a.b.c.d/19 le 32
or similar.
-----Original Message-----
From: Nick Hilliard
Sent: Thursday, July 28, 2011 3:57 PM
To: [email protected]
Subject: Re: [c-nsp] IPv6 BGP on IOS-XR
On 28/07/2011 19:33, Lee Starnes wrote:
Does anyone have any recommended reading for doing IPv6 BGP peering on
IOS-XR? We setup our peer with Cogent and can get full routes in, but
can't
seem to figure out how to announce our /32. I had assumed it setup just
the
same way as IPv4, but can't seem to get it to announce out. I did some
searching on Cisco's site, but didn't really find anything that pertained
to
how/what to announce and what not to announce.
bgp in xr is different from vanilla ios in that by default, it applies an
implicit deny on outbound prefixes. Regular IOS applies an implicit
permit, which leads to prefix leakages. XR definitely takes a more
sensible approach here.
What you need to do is to set up a route-policy for your neighbour, and
hook that route policy to whatever mechanism you want for prefix
redistribution. Let's say in this example you want to hook it into a
static prefix list:
prefix-set my-ipv6-prefixes
2001:db8:1234::/48
end-set
route-policy my-ipv6-policy
if destination in my-ipv6-prefixes then
pass
else
drop
endif
end-policy
router bgp 65432
neighbor 2001:db8:ffff::1
address-family ipv6 unicast
route-policy my-ipv6-policy out
[...]
Obviously, you can hook the route-policy into any filtering mechanism you
want.
I am a total fan of XR's RPL. It makes regular IOS route-maps look
lame-ass in comparison.
Nick
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