Re: protocol field according to RFC1661
James Carlson <[email protected]>
| Newsgroups | gmane.ietf.pppext |
|---|---|
| Message-ID | <[email protected]> |
Pavel Zeldin writes: > RFC1661 states (page 6): > "The Protocol field is one or two octets,.." Yes. > and further down > "the least significant bit of the least significant octet MUST > equal "1". Also, all Protocols MUST be assigned such that the > least significant bit of the most significant octet equals "0"." Right. > This does not quite work when protocol field is only one octet. Note that one is talking about encoding (on the wire format) and the other is talking about assignment (the IANA registry of protocols). The former allows one or two octet encodings, the latter uses *ONLY* two octet encodings. Specifically, when Protcol Field Compression is enabled, then protocols 0001 through 00FF may be encoded on the wire as a single octet (01 through FF). The assigned protocol is still described in terms of the two-octet form -- e.g., 0021 for IPv4. -- James Carlson, IP Systems Group <[email protected]> Sun Microsystems / 1 Network Drive 71.234W Vox +1 781 442 2084 MS UBUR02-212 / Burlington MA 01803-2757 42.497N Fax +1 781 442 1677 _______________________________________________ Pppext mailing list [email protected] https://www1.ietf.org/mailman/listinfo/pppext