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Re: /128 IPv6 prefixs in the wild?
From: "Justin M. Streiner" <streiner () cluebyfour org>
Date: Thu, 15 Dec 2011 09:15:36 -0500 (EST)

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


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