[147599] in North American Network Operators' Group
Re: /128 IPv6 prefixs in the wild?
daemon@ATHENA.MIT.EDU (Justin M. Streiner)
Thu Dec 15 09:16:38 2011
Date: Thu, 15 Dec 2011 09:15:36 -0500 (EST)
From: "Justin M. Streiner" <streiner@cluebyfour.org>
To: nanog@nanog.org
In-Reply-To: <CAPLq3UPwo0j3QDiSJLqsoOOPzaN_xmGyyzLGfic_DEC2H6mSRg@mail.gmail.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Thu, 15 Dec 2011, Glen Kent wrote:
> In the service provider networks, would we usually see a large number
> of /128 prefixs in the v6 FIB tables?
If you have /128s on the loopbacks of your routers, your other routers
could learn the /128s for the loopbacks of your other routers
through your IGP.
> What are the scenarios when IPv6 routers would learn a large number of
> /128 prefixes?
Two questions:
1. What is a 'large number' in this case?
2. Are the addresses from your v6 range(s), or something else that
wouldn't be coming from the outside world (link-local, etc)?
> I would presume that most IPv6 prefixes that the routers have to
> install are less than /64, since the latter 64 is the host part. Is
> this correct?
Looking at the routing table on one of my lab routers, I only see the /64
for a remote network in its v6 routing table, along with the interface and
link-local address of the router it wants to use to reach that
destination. I do not see any separate entries for any smaller chunks of
that /64.
jms
