tsvwg / draft-ietf-tsvwg-udp-options

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CMH: Instructions regarding placement of must-support options are overly prescriptive #48

Open Mike-Heard opened 2 months ago

Mike-Heard commented 2 months ago

In Section 10 I see;

>> "Must-support" options other than NOP and EOL MUST be placed by the transmitter before other UDP options and a receiver MUST drop all UDP options in such malformed packet (i.e., in which this ordering is not honored) and that event MAY be logged for diagnostics (logging SHOULD be rate limited).

The requirement that must-support options come before others is intended to allow for endpoints to implement DOS protection, as discussed further in Section 24.

This rule does not work for certain proposed options such as UCMP (and probably UENC), which must appear before other currently-defined options. So the proper requirement to levy on the transmitter is that it SHOULD place the "must-support" options before other UDP options. And even if this were not the case, it would IMO be overly prescriptive to require that the receiver drop the entire options area if this dictum is not respected. It is out of line with the less prescriptive advice in Section 24 (and the advice in Section 11.2 regarding repeated NOPs), which IMO is quite sufficient. Proposed replacement text:

>> "Must-support" options other than NOP and EOL SHOULD be placed by the transmitter before other UDP options.

The requirement that must-support options should come before others is intended to allow for endpoints to implement DOS protection, as discussed further in Section 24.