Re: [CCAMP] WG Last Call on draft-ietf-mpls-tp-ach-tlv-02.txt

[Curtis Villamizar <[e-mail]>]

In message <[e-mail]>
Loa Andersson writes:
>  
> All,
>  
> this is to start a three week MPLS working group last call on
>  
> http://www.ietf.org/internet-drafts/draft-ietf-mpls-tp-ach-tlv-02.txt
>  
> Please review and send your comments only to the [e-mail]
> mailing list.
>  
> The working group last call end March 28, 2010.
>  
> Loa and George


This would be a good time to define a capabilities TLV with wording to
indicate that IANA will assign capabilities identifiers.

  x.x  Capabilities

    This TLV specifies a set of capabilities to be defined as needed
    if an when it becomes advantageous for each end to agree on the
    use of specific protocol extensions.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         AchTlvType = TBD      |        Length = 2             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Capability Number    |E|Req|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Capability Number - To be assigned by IANA as needed by future
      RFCs

      E - the enabled bit

        0 - currently disabled
	1 - currently enabled

      Req - requirement code

        11 - requires that thie capability ben enabled
	10 - requires that this capability be disabled
	01 - prefer that this capability be enabled
	00 - don't care if capability is enabled or disabled

    The Req bits contain a "prefer" and a "don't care" so that a
    difference of preference resolves to "enable".  If one end
    indicated Req=11 and the other indicates Req=10, then
    administrative action may be required.  These values should only
    be used in situations where the network equipment cannot function
    properly with a capability enabled or disabled.

    Absense of this TLV for a given capability indicates no change
    from prior value.  If an unknown capability is recieved, a TLV
    with E=0 and Req=10 SHOULD be returned.  Absense of a prior TLV
    for a given capability MUST be interpreted as E=0 and Req=10.

Is this a reasonable addition?  I hope we don't exceed 8K extensions!

Curtis