IPv6 /48 advertisements

Antonio M. Moreiras moreiras at nic.br
Wed Dec 18 16:53:28 UTC 2013

What do you recommend to an end user that have a direct assignment of a
/48, and would like to disaggregate as part of a traffic engineering


On 18/12/13 14:32, Blake Dunlap wrote:
> Regardless of the carriers, you'll find most ASs on the internet only
> listen to /48 or larger. So even if you get your prefixes accepted by your
> provider, don't assume you can get anywhere, or have your packets not fall
> in to uRPF blackholes randomly without a larger aggregate announcement.
> -Blake
> On Wed, Dec 18, 2013 at 10:22 AM, Edward Dore <
> edward.dore at freethought-internet.co.uk> wrote:
>> If you’re talking about announcing each location separately, then RIPE
>> have a couple of useful articles about prefix visibility on Ripe Labs:
>> https://labs.ripe.net/Members/emileaben/ripe-atlas-a-case-study-of-ipv6-48-filtering
>> https://labs.ripe.net/Members/dbayer/visibility-of-prefix-lengths
>> Otherwise I guess you’ll need to talk to your chosen carrier(s) about
>> aggregating your space for you, which will come down to their policies on
>> what routes they will carry internally.
>> Edward Dore
>> Freethought Internet
>> On 18 Dec 2013, at 16:11, Cliff Bowles <cliff.bowles at 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.
>>> CWB
>>> ________________________________
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