Re: [dhcwg] Ben Campbell's Discuss on draft-ietf-dhc-relay-port-08: (with DISCUSS and COMMENT)

Ted Lemon <mellon@fugue.com> Thu, 30 November 2017 12:36 UTC

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From: Ted Lemon <mellon@fugue.com>
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Date: Thu, 30 Nov 2017 07:36:24 -0500
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Cc: Ben Campbell <ben@nostrum.com>, The IESG <iesg@ietf.org>, "draft-ietf-dhc-relay-port@ietf.org" <draft-ietf-dhc-relay-port@ietf.org>, dhcwg <dhcwg@ietf.org>, "dhc-chairs@ietf.org" <dhc-chairs@ietf.org>
To: "Naiming Shen (naiming)" <naiming@cisco.com>
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Subject: Re: [dhcwg] Ben Campbell's Discuss on draft-ietf-dhc-relay-port-08: (with DISCUSS and COMMENT)
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I'm sorry to belabor this, but I'm realizing that there's a bit of ambiguity in the new text in that there are actually two types of messages sent by relays: server-direction and client-direction.   The current text doesn't make that distinction:

Relay agents implementing this specification may be configured instead to use a source port number other than 67, and to receive responses on that same port. This will only work when the DHCP server or relay agent to which such a relay agent is forwarding messages is upgraded to support this extension.

I do not know what the actual intention is—if all relay messages toward clients come from port 67, there's no problem.   All relay messages to clients _have_ to come from port 67.   It could be that you intend relay messages from relays to relays in the direction of clients to come from a different source port.   But right now I think that the text is just about messages from relays to relays or servers, in the direction of servers.   Is that correct?   If so, the easiest change would be something like this:

Relay agents implementing this specification may be configured instead to use a source port number other than 67 when relaying messages toward servers, and to receive responses toward clients on that same port. This will only work when the DHCP server or relay agent to which such a relay agent is forwarding messages is upgraded to support this extension.