Subject: [v6ops] new draft: draft-v6ops-jaeggli-pmtud-ecmp-problemv6op6

From: Ray Hunter <[email-masked]>
Date: Tue, 18 Feb 2014 08:57:16 +0100

> From: <fred at cisco.com>
> To: v6ops at ietf.org
> Cc: draft-v6ops-jaeggli-pmtud-ecmp-problem at tools.ietf.org
> Date: Mon, 17 Feb 2014 05:45:16 -0800 (PST)
> A new draft has been posted, at 
> http://tools.ietf.org/html/draft-v6ops-jaeggli-pmtud-ecmp-problem. 
> Please take a look at it and comment.

I have read this draft.

Isn't the obvious brute force mitigation to clamp all of your DC to IPv6 
minimum MTU?

And isn't it yet another hint that PMTUD really needs to be incorporated 
into the transport layer [if we needed another]?

e.g. by referencing Packetization Layer Path MTU Discovery (PLPMTUD) 
http://tools.ietf.org/html/rfc4821

That should also be handled correctly by the load balancers, or not?

-- 
Regards,
RayH

---

From: joel jaeggli <[email-masked]>
Date: Tue, 18 Feb 2014 07:22:14 -0800

> Isn't the obvious brute force mitigation to clamp all of your DC to IPv6

That is an obvious brute force mitigation.

It does however doom ipv6 to the minimum mtu until I decide pmtu is no
longer necessary, which may or may not be never.

There wouldn't be much point if this happened frequently but as it is,
it happens at a rate of a handful of packets per second out of a few
gig's of v6 traffic. That says a lot I think about deployment.

> http://tools.ietf.org/html/rfc4821

Sure I agree that in-band signaling would be way less likely to interact
badly with ecmp forwarding decisions.