minimum IPv6 announcement size

William Herrin bill at
Tue Sep 24 18:33:41 UTC 2013

On Tue, Sep 24, 2013 at 9:49 AM, Nathanael C. Cariaga
<nccariaga at> wrote:
> 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.

Hi Nathanael,

Many if not most networks set a limit at /48. Verizon was the last
player of consequence to filter at /32, and they moved to /48 a couple
years ago. A few also try to limit advertisements within ISP space
nearer to /32. Usually not at /32, but a /48 announcement within space
allocated to an ISP won't necessarily be honored.

If you have distinct networks with distinct routing policies (or can
make a reasonable claim to such) and your RIR is ARIN, you can request
a block size large enough to provide a /48 to each distinct network. A
/44 or whatever. Search through the ARIN NRPM for details. I don't
know about the other RIRs; someone in your region (Asia Pacific?) will

Bill Herrin

William D. Herrin ................ herrin at  bill at
3005 Crane Dr. ...................... Web: <>
Falls Church, VA 22042-3004

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