[AusNOG] Vyatta IPv6 Ping Responses

[Karl Auer]

On Tue, 2014-11-25 at 14:29 +1100, daniel at glovine.com.au wrote:
> We have setup our interface with 2400:d400:ffff:5332:4::1/126
> We try and ping our gateway of 2400:d400:ffff:5332:4::

So the local interface is P::1 and the other interface is P::0, both in
P::/126?

What you've done is give the router interface the subnet anycast address
for P::/126, which probably isn't what you wanted. With a /126, normally
used on a point to point link, it would be more usual to have one end be
P::1/126 and the other end be P::2/126. P::0/126 is then the router
anycast address and P::3/126 is unused.

Since this is a point to point link it would be even more usual to
configure a /127 on the link, and have the addressing you mention. /127
is a special case - interfaces in such a network do not configure a
subnet router anycast address (unless you are using hardware or software
that is oldish, in which case you have to use a /126 to get around the
subnet router anycast conflict).

> However when we ping the gateway we get a response from
> 2400:d400:ffff:5332:4::1 with a valid pong ms response

Not sure if the local device is a router or a host. I'm guessing this is
two routers on a point to point link. It looks a bit as if your local
interface ended up owning the subnet router anycast address P::0/126, so
it will respond when people ping that address. Not sure what the other
router is actually doing - but my guess is it now has an address
conflict :-)
 
> If anybody knows how I can resolve this, would be highly appreciated

Either move to a /127 with P::0/127 on one end and P::1/127 on the
other, or change the addressing in your /126 so that you have P::1/126
on one end and P::2/126 on the other.

The above notation is not real, but it reduces things to the bits that
matter. Obviously replace "P::" with the actual prefix you are using.

Regards, K.

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Karl Auer (kauer at biplane.com.au)
http://www.biplane.com.au/kauer
http://twitter.com/kauer389

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