[j-nsp] Re: ICMPv6 "packet too big" not being emitted

[Daniel Roesen]

On Tue, Jan 10, 2006 at 07:33:44PM +0100, Daniel Roesen wrote:
> On Tue, Jan 10, 2006 at 08:06:21PM +0200, Pekka Savola wrote:
> > IPv6-in-IPv4 tunneling on Juniper has worked fine for us for a long 
> > time (maybe from around 5.4R era) after glueing in MTU=1480. 
> > Otherwise, it'd cause the exact PMTUD issues you describe, which we 
> > finally got through as PR65486.
> 
> Well, I guess your problem was because of the tunnel payload MTU being
> derrived from the underlying egress interface MTU? That's known
> behaviour of both Cisco and Juniper. So manually configuring the payload
> mtu (as I wrote in the email) is always a good idea.

I've just taken a look at PR65486... from the description I understand
that you noticed Juniper behaving like Cisco (not doing PMTUD on tunnel
packets and thus not dynamically adjusting tunnel payload MTU). Would be
a nice enhancement indeed - but wouldn't solve the problem here. The
configured tunnel MTU is correct, but the router doesn't emit the
necessary ICMPv6 "packet too big".


Best regards,
Daniel

-- 
CLUE-RIPE -- Jabber: dr at cluenet.de -- dr at IRCnet -- PGP: 0xA85C8AA0