Re: [dhcwg] [v6ops] [EXTERNAL] Re: Question to DHCPv6 Relay Implementors regarding draft-ietf-dhc-dhcpv6-pd-relay-requirements

"Templin (US), Fred L" <> Fri, 09 October 2020 14:02 UTC

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From: "Templin (US), Fred L" <>
To: Ole Troan <>
CC: dhcwg <>, v6ops list <>, 6man <>
Thread-Topic: [dhcwg] [v6ops] [EXTERNAL] Re: Question to DHCPv6 Relay Implementors regarding draft-ietf-dhc-dhcpv6-pd-relay-requirements
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Date: Fri, 9 Oct 2020 14:01:54 +0000
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Subject: Re: [dhcwg] [v6ops] [EXTERNAL] Re: Question to DHCPv6 Relay Implementors regarding draft-ietf-dhc-dhcpv6-pd-relay-requirements
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Responding to myself since folks seem to have blasted past this proposal:

> So, why not fix the problem at the client instead of at the relay? The client could
> have a simple check to make sure it does not forward a packet out the same
> interface that it arrived on due to a default route. That way, the relay would
> never see a packet originating from node A with a destination address A.
> (BTW, it should be OK for the client to forward a packet out the same interface
> it arrived on due to  a more-specific route - but not due to a default route.)

The problem that is being described is a client problem; not a relay problem.
So, why not fix it in the client? Fixing it in the client also avoids wasted message
transmissions on the link from the client to the relay since packets that would
cause a loop would never be transmitted by the client at all. This is very important
for some link types such as aviation data links where the data rates are low to
begin with.