IPv6 /48 advertisements

Chuck Anderson cra at WPI.EDU
Wed Dec 18 16:16:56 UTC 2013

On Wed, Dec 18, 2013 at 09:11:46AM -0700, Cliff Bowles wrote: 
> Question: will carriers accept IPv6 advertisements smaller than /48?

Not generally, no.

> Our org was approved a /36 based on number of locations. The bulk of
> those IPs will be in the data centers. As we were chopping up the
> address space, it was determined that the remote campus locations
> would be fine with a /60 per site. (16 networks of /64). There are
> usually less than 50 people at the majority of these locations and
> only about 10 different functional VLANs (Voice, Data, Local
> Services, Wireless, Guest Wireless, etc...).
> Now, there has been talk about putting an internet link in every
> campus rather than back hauling it all to the data centers via
> MPLS. However, if we do this, then would we need a /48 per campus?
> That is massively wasteful, at 65,536 networks per location.  Is the
> /48 requirement set in stone? Will any carriers consider longer
> prefixes?

/48 per site is the standard.

> I know some people are always saying that the old mentality of
> conserving space needs to go away, but I was bitten by that IPv4
> issue back in the day and have done a few VLSM network
> overhauls. I'd rather not massively allocate unless it's a
> requirement.

You need to throw out all old thinking in terms of what happened in
IPv4.  Current ARIN policy allows a /48 per site and that is how you
should architect the network.

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