Re: ICMP6 redirect

Hesham Soliman <> Tue, 24 July 2012 04:46 UTC

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Date: Tue, 24 Jul 2012 14:45:59 +1000
Subject: Re: ICMP6 redirect
From: Hesham Soliman <>
To: Andrew McGregor <>
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Thread-Topic: ICMP6 redirect
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>>=> The router doesn't need to know the host's route table, it knows which
>> address it included in its RAs, which is what the host records.
>> I'm not sure why you think that there is no way the router can construct
>> that message reliably. If it uses the same address it uses for its RAs,
>> can construct the message.
>Ah.  Well, that will certainly help, but consider a situation where there
>are no RAs, 

=> Where is that situation possible/deployed? It's hard to consider
something that is against the spec you're commenting on :)

>or the host has a manual static route.  Arguably misconfigured, I know,
>but if we have that situation a router cannot know what address the host
>was sending to, only that it is one of its own.  For that matter, there
>may be many RAs being generated through that interface, and do we
>necessarily know which it was that caused the host/peer to route through

=> Well, it depends on your implementation I guess. If your router
randomly assigns src addresses to RAs with arbitrary prefixes then I can
see where it would get confusing very quickly. But if they're doing it in
a structured way it will work.

That's why I raised a comment against your premise of "no way to do it
reliably". There is definitely a way to do it reliably.