-proto-05: Final Format of "Bandwidth Constraints" sub-TLV

["Francois Le Faucheur (flefauch)" <flefauch@cisco.com>]

Hello,

As discussed, in response to a comment from the IESG review of
draft-ietf-tewg-diff-te-proto-05.txt, we're proposing to correct the
format of the "Bandwidth Constraints" sub-TLV (section 5.1)to ensure
32-bit alignment. 

My initial proposal mentioned on the list was to simply add a 3-byte
Reserved field. See "New Format Without Bitmap" below.

But it occurred to me that we could take advantage of one of the added
bytes to provide a bit-map of which BC constraints are actually included
in the sub-TLV. That way, if it happens that only CT0 and CT7 are used
(and thus only BC0 and BC7 are configured), the LSR could include only
BC0 and BC7 in the sub-TLV (rather than be forced to include all 8 BCs
as assumed by current format). See "New Format With Bitmap" below.

I am leaning towards "new Format WITH Bitmap". 

Anyone has issues with "New Format With Bitmap"? 
Other thoughts/comments?


Old format (as per -proto-05):
==============================
"
"Bandwidth Constraints" sub-TLV: 
- Bandwidth Constraint Model Id (1 octet) 
- Bandwidth Constraints (Nx4 octets) 
"

New Format Without Bitmap:
==========================
"
"Bandwidth Constraints" sub-TLV: 
- Bandwidth Constraints Model Id (1 octet)
- Reserved (3 octets) 
- Bandwidth Constraints (Nx4 octets) 
+ some text explaining that "Reserved" is to be set to zero on transmit,
ignored on receipt.
"

New Format With Bitmap:
=======================
"
"Bandwidth Constraints" sub-TLV: 
- Bandwidth Constraints Model Id (1 octet)
- Bandwidth Constraints Bitmap (1 octet)
- Reserved (2 octets) 
- Bandwidth Constraints (Nx4 octets)
+ some text explaining that :
	* "Reserved" is to be set to zero on transmit, ignored on
receipt.
	* "Bitmap" is a set of 8 flags each indicating if the
corresponding BC is included in sub-TLV (eg. 10100001 means that BC0,
BC2 and BC7 will be included).
"

Cheers
Francois