[dhcwg] Adam Roach's No Objection on draft-ietf-dhc-relay-port-07: (with COMMENT)

[Adam Roach <[e-mail]>]

Adam Roach has entered the following ballot position for
draft-ietf-dhc-relay-port-07: No Objection

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COMMENT:
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Thanks for your time on this document. I have one minor correction and two
questions.

The introduction says: "...for IPv6 the server port is (546) and the client
port is (547)."  I believe this is backwards.

Section 5.2 says:

   If this option is included to
   indicate only the local non-DHCP UDP port usage and there is no
   downstream relay agent's non-DHCP UDP port usage, the field
   Downstream Source Port field MUST be set to zero.

Was the use of length=0 considered rather that port=0 here? The reason I ask is
that UDP port 0 is *reserved*, but not technically *invalid*, and the use of
"length=0" would distinguish between the flag usage and the port usage while
not precluding the valid (if admittedly rare) use of port=0.

Finally, I have a question about DHCPv6 relay agent chains that arose in
reading the document. The example section actually gives a pretty good jumping
off point to ask the question, so I'll quote an excerpt here:

   Similar to the above example, now assume that Relay2 uses the UDP
   source port of 2000 instead of 547 as in the diagram.  The Relay3
   device needs to support this DHCP extension and it will set 2000 in
   its "Downstream Source Port" field of the option in the Relay-forward
   message.  When DHCP server sends the DHCP Relay-reply to Relay3,
   Relay3 finds its own relay option has this "Downstream Source Port"
   with the value of 2000.  Relay3 will use this UDP port when sending
   the Relay-reply message to Relay2.

If we were to continue this paragraph all the way back to Relay1, it's not
clear how Relay2 would know to use port 1000 when sending its Relay-reply
message to Relay1. Does this mechanism have a limitation that only one Relay
Agent in the forwarding chain is allowed to use a Non-DHCP UDP Port?