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Re: IPv6 /48 advertisements
From: Laszlo Hanyecz <laszlo () heliacal net>
Date: Wed, 18 Dec 2013 16:36:39 +0000

It's standard to filter out anything longer than /48.

Your /36 prefix was chosen based on the number of sites, with a /48 per site, so just keep it simple.  Trying to manage 
it in the way IPv4 addresses were managed will just ensure that you will have the same headaches of micro managing sub 
allocations and trying to guess the right sizes.  The address space in V6 is large enough that you don't have to spend 
your time worrying about this, and that's one of the reasons for using a /48 at each site.

Think of an IPv6 /48 like you would think of an IPv4 /24 - except that it's the right size for either your house or 
your university campus.


On Dec 18, 2013, at 4:11 PM, Cliff Bowles <cliff.bowles () apollogrp edu> wrote:

I accidentally sent this to nanog-request yesterday. I could use some feedback from anyone that can help, please.

Question: will carriers accept IPv6 advertisements smaller than /48?

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?

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.

Thanks in advance.


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