using "reserved" IPv6 space

Karl Auer kauer at
Tue Jul 17 07:15:00 UTC 2012

On Mon, 2012-07-16 at 23:36 -0700, Owen DeLong wrote:
> Reread the spec... [the subnet router anycast address] gets the packet
> to one or more of the routers and it may well lead to packet
> duplication. There may or may not be coordination between the
> routers. It isn't in the spec.

Which spec? Looking at RFC 4291, Section 2.6.1:

   Packets sent to the Subnet-Router anycast address will be delivered
   to one router on the subnet.  All routers are required to support the
   Subnet-Router anycast addresses for the subnets to which they have

   The Subnet-Router anycast address is intended to be used for
   applications where a node needs to communicate with any one of the
   set of routers.

But I do not have an encylopaedic knowledge of all the RFCs, so perhaps
this has been superseded, obsoleted or updated...

Reading it with a squint: The phrase "packets [...] will be delivered to
one router on the subnet"  does not specifically exclude the possibility
that packets will be delivered to more than one router on the subnet.
Still, I do think it would be a little unreasonable to interpret it

Regards, K.

Karl Auer (kauer at

GPG fingerprint: AE1D 4868 6420 AD9A A698 5251 1699 7B78 4EEE 6017
Old fingerprint: DA41 51B1 1481 16E1 F7E2 B2E9 3007 14ED 5736 F687
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 230 bytes
Desc: This is a digitally signed message part
URL: <>

More information about the NANOG mailing list