Requested revision
Standard: | 802.1Q-2011 | Clause: | Annex D |
Clause title: | IEEE 802.1 Organizationally Specific TLVs |
Rationale for revision
(Submitted on behalf of David Law) In the original specification of
the Port and Protocol VLAN ID TLV found in Figure F-2 of IEEE Std
802.1AB-2005, the bits in the 'flag' field are numbered 0 to 7 with
bit 0 reserved, the 'supported' bit in bit 1, the 'enabled' bit in bit
2, and bits 3 to 7 are reserved. Looking at Figure D-2 of IEEE Std
802.1Q-2011 the bits in the 'flag' field are now numbered 1 to 8, but
the 'supported' bit is still in bit 1, the 'enabled' bit is still in
bit 2, and now bits 3 to 8 are reserved. It appears the position of
the 'supported' and 'enabled' bits in the octet have changed, which
doesn't seem to be correct. The version shown in 802.1Q looks to be
the same as the version published in 802.1AB-2009.
This seems to have happened as a result of an attempt to align the bit
numbering in AB to be consistent with bit numbering usage in 802.1Q;
however, there is at least one other instance in 802.1Q-2011 of but
numbering starting at 0 (see Figure D-7).
Proposed text
Need to discuss what to do about Figure D-2 - the two TLV definitions
(AB-2005 vs AB-2009/Q-2011) are clearly different.
Ideally, 802.1Q should be fixed so that bit numbering is consistent everywhere.
Impact on existing networks
Not clear - depends entirely on how widely the Port and Protocol TLV is used.
Inconsistent representations can lead to misinterpretation.
Originator
Name: | Tony Jeffree | Email: | tony@jeffree.co.uk |
Affiliation: | HP/Broadcom | ||
Submitted: | 2012-12-04 |