Putting on the list a comment I made in the meeting, and adding more info too...
Section 2 says: > The REQUESTED port may be used as a source port if the application > exclusively uses multicast messages. If any application messages are > unicast, then a dynamic port should be used as the source port. This > allows receivers to know which port to send replies to. The context of my comment is applications that do some sort of multicast discovery where a multicast message is sent to solicit one or more unicast replies. My comment in the meeting is that the text in section 2 requires the app use a separate socket for the reply (at least on some unmodified platforms). That requirement is new and so should be stated explicitly. After I made the comment, it also occurred to me that this restriction may also cause problems with some host firewalls. Specifically, I suspect some will simply drop the unicast reply, breaking multicast discovery mechanisms if this document is implemented with the section 2 restriction. That is, I believe some host firewalls will filter by the unicast source port == the multicast destination port that went outbound. So I would recommend discussing that explicitly in the document, since I'm afraid the stated restriction might cause breakage. (And if you do add text about host firewalls, consider referencing IAB RFC 7288.) Dave _______________________________________________ Int-area mailing list -- int-area@ietf.org To unsubscribe send an email to int-area-le...@ietf.org
