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

[Rahul Aggarwal <rahul@juniper.net>]

Hi Francois,

On Tue, 23 Dec 2003, Francois Le Faucheur (flefauch) wrote:

> 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?
>
>

It is not clear why an operator would want to configure non contigous
class types ? The new format without the bitmap seems preferable, as the
bitmap may not be useful in practice.

Thanks,
rahul



> 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
>
>