On Mar 25, 2014, at 5:20 PM, Suresh Krishnan <[email protected]>
wrote:
> * Section 4.1 (b)
>
> The following text is unclear.
>
> "if the relay agent receives the message for which it is not the target
> according to the message type."
>
> The text that follows talks about new server-to-relay messages sent to the
> relay agent being forwarded back to the server. Such a message will not meet
> either of the conditions laid out in Section 4.1.
It might be better to make point (b) this way:
(b) if the relay agent receives the message for which it does
not identify itself as the target.
At present the only DHCP message that could be intended for a relay
agent would be a LEASEQUERY-REPLY message [RFC5007]. Such messages
are only correctly generated in response to LEASEQUERY messages sent
by a relay agent acting as a leasequery requestor. It is therefore
expected that such messages will be able to be identified by relay
agents.
The text that follows is intended to address the case where a new message type
is defined that is intended to be sent, unsolicited, to a relay agent. It
might be made clearer as follows:
New DHCP message types may be defined in future that are sent,
unsolicited, to relay agents. Relay agents
that do not implement these messages will not recognize such
messages as being intended for them. A relay agent that implements this
specification will therefore forward such messages to the DHCP
servers to which it is configured to relay client messages.
At this time, no such message types have been specified. If
such a message is specified in the future, it is possible that this
would result in needless load on DHCP servers. If such a message
type is defined in a future specification, authors may need to
consider some strategy for identifying non-conforming relays and
not sending such messages to them.
However, since DHCP servers do not respond to unknown messages,
this is unlikely to create significant load, and therefore is
likely to be unnecessary.
> The following text seems extraneous
>
> " However, this is not strictly necessary, since DHCP does not provide
> a signaling message for rejecting unexpected message types, and
> therefore DHCP servers are not expected to respond to such messages."
>
> What exactly is "this" referring to? The DHCP server is not responding anyway
> to such messages.
The reason for not just deleting this text is that it _is_ possible to define
an unsolicited relay message in such a way that it could cause problems, so the
author really does need to think about it, and it's reasonably likely that they
will read this advice before doing so, or at least that someone who reviews the
document will be aware of this advice.
> * Section 4.2
>
> The prescribed behavior here is contradicts the text in section 4.1 defining
> a valid message. Specifically, what happens when a relay receives an unknown
> message type for which it is the intended target. According to 4.1, the relay
> does nothing. According to 4.2 the relay forwards.
No, according to 4.1 it forwards as well, unless it's the intended recipient of
the message. And it can only tell that it's the intended recipient if it
understands that type of message. So the two sections do not contradict each
other. Hopefully this is more clear with the new text. Stephen Farrell
raised some related questions; updating the text as I've suggested should
address his concerns as well.
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