Too bigs are sacred, was: Re: IPv6 addressing for core network

David Freedman david.freedman at
Wed Feb 9 17:26:46 CST 2011

> Unless every packet you emit is ¾ the minimum MTU (1280), then, you need
> to be able to receive TOOBIG messages.

Can you think of a packet type I will emit from my publically numbered
backbone interface which may solicit a TOOBIG that I'll have to care about?

I can only think of three cases, all ICMP:

1. An unreachable of some kind (I don't care if this is delivered or not,
and why would I be sending them from the backbone? Even rate-limited? If I
send them at all this is the responsibility of the edge)

2. A Time Exceed, again, don't care if this is delivered or not

3. A TOOBIG, if I'm getting a TOOBIG in response to my TOOBIG then we all
have bigger problems to worry about :)


> Owen


David Freedman

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