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Re: Forwarding Packets With Link Local Destination Addresses

Fred Baker <fredbaker.ietf@gmail.com> Thu, 07 January 2021 18:45 UTC

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From: Fred Baker <fredbaker.ietf@gmail.com>
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Subject: Re: Forwarding Packets With Link Local Destination Addresses
Date: Thu, 07 Jan 2021 10:45:43 -0800
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To: Ron Bonica <rbonica=40juniper.net@dmarc.ietf.org>
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On Jan 7, 2021, at 9:54 AM, Ron Bonica <rbonica=40juniper.net@dmarc.ietf.org> wrote:
> According to RFC 4291, “routers must not forward any packets with Link-Local source or destination addresses to other links”.

This, of course, imposes a requirement that no routers I’m aware of carry out absent explicit configuration, which is to make a forwarding decision (in this case a filter) based on the source address. Reverse forwarding lookups *might* accomplish this by associating link local addresses with the interface the packet it was received on, but that would only happen if reverse address lookups (normally associated with BCP 38) were enabled. 

So one could argue that RFC 4291 goes beyond its remit in this regard.
>

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