RE: Label Set Object

[John Drake <jdrake@calient.net>]

Is it the case that ALL current SONET/SDH equipment has the restriction that
the labels (timeslots) must be the same in both directions?  If this is the
case, then it's really simple; for an SONET/SDH LSP, only the upstream label
needs to be specified, and the downstream label MUST be the same.

One the other hand, if not all current SONET/SDH equipment has this
restriction or the current SONET/SDH standards allow the labels (timeslots)
to be different in each direction, then label set with one value or explicit
label control would be useful for equipment that does have this restriction.


-----Original Message-----
From: Suresh Katukam [mailto:skatukam@cisco.com]
Sent: Wednesday, May 08, 2002 3:23 PM
To: Zafar Ali
Cc: Manoj Agiwal; Manoj Agiwal; 'Ccamp (E-mail); mpls@UU. NET (E-mail)
Subject: RE: Label Set Object



For TDM, since you have to use same labels in both directions, why do you 
have to specify anything at all?
How can a downstream TDM node pick a label that does not match with 
Upstream label for
a bidirectional LSP? If it picks any other label, LSP is not functional.

If there are Uni-directional LSPs in TDM and if you have different types of 
time slots available
in both directions, then one may be able to setup bidirectional LSP on 
different links or
different labels. This is in theory and not in practice.

So in practice, one does not need to specify LABEL SET or Suggested label 
for TDM links.

Thanks,
Suresh

At 01:53 AM 5/8/2002 -0400, Zafar Ali wrote:
>At 11:11 AM 5/8/2002 +0530, Manoj Agiwal wrote:
>>Hi ,
>>    I guess in that case we can use Suggested Label , Label Set still can 
>> still be avoided .
>
>Hi Manoj,
>
>No, the use of suggested label in this case would NOT be correct, as the 
>suggested labels can be ignored/ overridden by the receiving node.
>
>Thanks
>
>Regards... Zafar
>
>>Regards ,
>>Manoj
>>-----Original Message-----
>>From: Zafar Ali [mailto:zali@cisco.com]
>>Sent: Wednesday, May 08, 2002 11:05 AM
>>To: Manoj Agiwal; 'Ccamp (E-mail)
>>Cc: mpls@UU. NET (E-mail)
>>Subject: Re: Label Set Object
>>
>>At 10:00 AM 5/8/2002 +0530, Manoj Agiwal wrote:
>>>Hi ,
>>>        In gmpls signaling extensionsions for RSVP-TE , ccamp 
>>> architecture on
>>>gmpls has described Label Set object usage
>>>     only for the "optical" domain viz. for carrying wavelengths (
Section
>>>9.9 draft-ietf-ccamp-gmpls-architecture-02.txt) .
>>>
>>>        Do we require to send Label set(i.e. time slots) for TDM 
>>> switching as
>>>well . In what way it can be useful .
>>Dear Manoj,
>>
>>Yes, label set object is also useful in TDM case. E.g., SONET poses an 
>>additional requirement that the two interfaces of a bidirectional LSP 
>>SHOULD traverse the exact same link with the same SUKLM values for the 
>>two directions.
>>  The label set object can be used to constrain the downstream label to 
>> the same as the upstream label.
>>
>>Thanks
>>
>>Regards... Zafar
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>>Regards ,
>>>Manoj
>>===============
>>Zafar Ali
>>Cisco Systems
>>(734) 276-2459
>>100 S Main St. #200
>>Ann Arbor, MI 48104.
>>email: zali@cisco.com
>
>===============
>Zafar Ali
>Cisco Systems
>(734) 276-2459
>100 S Main St. #200
>Ann Arbor, MI 48104.
>email: zali@cisco.com