6.1. IP and UDP Headers
Any PANA message is unicast between the PaC and the PAA. The source
and destination addresses SHOULD be set to the addresses on the
interfaces from which the message will be sent and received,
respectively.
It is nonsensical to talk about the sender of a message setting the
destination IP address to anything other than the address that will
eventually lead to an interface on a PAA.
As for the source address, it sounds as if you are saying that the PANA
message SHOULD not be spoofed. I think it is very important to get this
source address correct, particularly if the Device ID is a source IP
address, and this same source IP address is going to be used to setup
filters (as per our previous discussion).
The source port of an unsolicited PANA message MUST be set to a value
chosen by the sender. The destination port MUST be set to the peer's
port number if it has already been discovered via earlier PANA
exchanges, set to the assigned PANA port (To Be Assigned by IANA)
otherwise.
What is meant by "earlier PANA exchanges"? If a PANA session has the
ability to move off of a registered UDP port, I would think that this
would only last for a given PANA session. For example, based on this
wording one might think: "Yesterday, when contacting PAA foo I used UDP
port number 12345. So, I must still be able to use 12345 today." Surely
that is not correct.
If by "unsolicited" you mean the initiating PANA messages (a PCI, for
example) then I believe it should always be sent on the IANA specified
port number. I'm not sure why you wouldn't want to make this true for
all PANA messages, in fact. It certainly makes implementations simpler
if the dest port is always the same, not to mention intervening
equipment that may need to snoop what is happening to open up filters,
or allow just PANA messages through for a period of time, etc. (DSLAMs,
for example, on a DSL access network, may need to do this). I would
highly recommend sticking to ONE dest UDP port, unless you really need a
reason to move off of it (and I'd like to know what that reason is).
- Mark
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