minimum IPv6 announcement size

joel jaeggli joelja at
Tue Sep 24 14:00:07 UTC 2013

On 9/24/13 6:47 AM, Otis L. Surratt, Jr. wrote:
> -----Original Message-----
> From: Nathanael C. Cariaga [mailto:nccariaga at] 
> Sent: Tuesday, September 24, 2013 8:50 AM
> To: NANOG Mailing List
> Subject: minimum IPv6 announcement size
>> Hi,
>> Just wondering if anyone could shed light on my concern.....
>> I've been Google-ing about if there is such a standard that sets the
> minimum IPv6 advertisement on BGP.  My concern is that I am running a
> network that is operating on multiple sites and currently rolling >out
> our IPv6 on the perimeter level.  Having to get our /48 allocation from
> our RIR, I figured out I would it would be best for us to break down the
>> /48 into smaller chunks (i.e /56s) and farm it out to our sites since a
> single /48 will be very big for our single site.

Your RIR ought to make a minimum allocation based on the number of sites
you need to deploy to, so something shorter than a /48. clearly you
should aim for the highest acheiveable aggregation but that's not always

the fact that it is "large for your site" isn't germain to the
discussion of what's the minimally accepted size prefix.

>> Any advise will be very much appreciated.
>> Regards,
>> --
>> -nathan
> Minimum announcement for IPv6 as I recall is /48. Some providers might
> accept less for their networks.

I've seen providers accept longer but not propigate them. we apply
filters at the /48 level, That appears to be sufficiently common that it
confers herd immunity to shorter prefixes.

> -Otis

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