Subject: RE: Label Set Object

From: John Drake <[email-masked]>
Date: Wed, 8 May 2002 13:07:22 -0700

Label Set and Explicit Label Control are used for different purposes, and as
I understand it, Explicit Label Control is more natural  for establishing
SONET/SDH LSPs, while Label Set is more natural for establishing wavelength
LSPs.  You could, however, use Label Set for SONET/SDH LSPs and Explicit
Label Control for wavelength LSPs.

-----Original Message-----
From: Juneja, Manoj [mailto:[email-masked]]
Sent: Wednesday, May 08, 2002 11:57 AM
To: John Drake; Juneja, Manoj; 'Zafar Ali'; Vinay Vernekar; Manoj Agiwal;
'Ccamp (E-mail)
Cc: mpls@UU. NET (E-mail)
Subject: RE: Label Set Object

Hi Jonh,
              Sorry for creating the confusion. Should the label set be used
for establishing the SDH/SONET LSPs ? 
 
Regards,
manoj.

-----Original Message-----
From: John Drake [mailto:[email-masked]]
Sent: Wednesday, May 08, 2002 11:50 AM
To: 'Juneja, Manoj'; 'Zafar Ali'; Vinay Vernekar; Manoj Agiwal; 'Ccamp
(E-mail)
Cc: mpls@UU. NET (E-mail)
Subject: RE: Label Set Object

I didn't say that.

-----Original Message-----
From: Juneja, Manoj [mailto:[email-masked]]
Sent: Wednesday, May 08, 2002 11:48 AM
To: John Drake; 'Zafar Ali'; Vinay Vernekar; Manoj Agiwal; 'Ccamp (E-mail)
Cc: mpls@UU. NET (E-mail)
Subject: RE: Label Set Object

Hi John,
               Did u mean Explicit label control is used only for SDH/SONET
case  and is not used for FSC/LSC LSPs ? If this is the case then it should
be clearly mentioned in the draft. Furthermore, it should also be mentioned
that label set is not used for SDH/SONET LSPs.
 
Regards,
manoj.

-----Original Message-----
From: John Drake [mailto:[email-masked]]
Sent: Wednesday, May 08, 2002 11:26 AM
To: 'Zafar Ali'; Vinay Vernekar; Manoj Agiwal; 'Ccamp (E-mail)
Cc: mpls@UU. NET (E-mail)
Subject: RE: Label Set Object

Explicit Label Control is used to handle the SONET/SDH case.  Its semantics
are different than Label Set, in the sense that there is one and only one
value, rather than a set that is manipulated end-end 
 
Thanks,
 
John
 
-----Original Message-----
From: Zafar Ali [mailto:[email-masked]]
Sent: Wednesday, May 08, 2002 10:31 AM
To: Vinay Vernekar; Manoj Agiwal; 'Ccamp (E-mail)
Cc: mpls@UU. NET (E-mail)
Subject: Re: Label Set Object

Dear Vinay, 

Please see comments in-lined. 

Thanks

Regards... Zafar 
At 07:56 PM 5/8/2002 +0530, Vinay Vernekar wrote:

Hi Zafar,
The Label Set Object can't be sent to constrain the downstream label when
the LSP encoding type is Sonet/SDH. Consider the example where a request is
sent to downstream with SONET/SDH traffic parameters as NVC=n and MT=m. The
label expected from the downstream would be 'm' set of labels each set
consisting of 'n' labels further that identify each of the virtual
concatenated components. So a Label Set in this scenario would consist of
say 'p' sets each consisting of 'm' sets of 'n' labels. Such a Label Set
cannot be encoded using the object/TLV structure of Label Set as in
"Generalized MPLS - Signalling Functional Description -
draft-ietf-mpls-generalized-signaling-08.txt". 

I think, this would be a second level question/ issue. IMO, we should be
able to build on the concept of a label set to incorporate technologies
other than WDM. Can we, in principle, agree on this or you are aware of an
alternative for the case you mentioned above? 

Label Set Object can be sent only in WDM scenario where a single wavelength
is requested as a label and the upstream has a restriction on the usable
wavelengths.

IMHO this would be an undesirable restriction. Why its cannot cover the
single label case in SONET? 

Correct me if I am going wrong anywhere.
 
Regards
Vinay    

----- Original Message ----- 
From: Zafar Ali <mailto:[email-masked]>  
To: Manoj  <mailto:[email-masked]> Agiwal ; 'Ccamp
<mailto:[email-masked]> (E-mail) 
Cc: mpls@UU. NET (E-mail) <mailto:mpls@UU. NET (E-mail)>  
Sent: Wednesday, May 08, 2002 11:04 AM
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: [email-masked]

---

From: Zafar Ali <[email-masked]>
Date: Wed, 08 May 2002 19:04:57 -0400

At 01:07 PM 5/8/2002 -0700, John Drake wrote:
>Label Set and Explicit Label Control are used for different purposes, and 
>as I understand it, Explicit Label Control is more natural  for 
>establishing SONET/SDH LSPs, while Label Set is more natural for 
>establishing wavelength LSPs.
>You could, however, use Label Set for SONET/SDH LSPs and Explicit Label 
>Control for wavelength LSPs.

Hi John,

While I agree with the last statement, I didn't understand why you 
mentioned that explicit label control is more natural for SONET/ SDH. IMHO 
the label set is a more natural way of constraining labels in all scenarios.

Any way, this is a non-debate, in the light of the email sent by Suresh in 
which he suggested that the constraints are implied by the nature of the 
TDM circuits. I agree with Suresh that there is no point of copying the 
same parameters using the other means, if they can be implied.

Thanks

Regards... Zafar
>               Sorry for creating the confusion. Should the label set be 
> used for establishing the SDH/SONET LSPs ?
>
>Regards,
>manoj.
>                Did u mean Explicit label control is used only for 
> SDH/SONET case  and is not used for FSC/LSC LSPs ? If this is the case 
> then it should be clearly mentioned in the draft. Furthermore, it should 
> also be mentioned that label set is not used for SDH/SONET LSPs.
>
>Regards,
>manoj.
>Explicit Label Control is used to handle the SONET/SDH case.  Its 
>semantics are different than Label Set, in the sense that there is one and 
>only one value, rather than a set that is manipulated end-end
>
>Thanks,
>
>John
>
>>the LSP encoding type is Sonet/SDH. Consider the example where a request 
>>is sent to downstream with SONET/SDH traffic parameters as NVC=n and 
>>MT=m. The label expected from the downstream would be 'm' set of labels 
>>each set consisting of 'n' labels further that identify each of the 
>>virtual concatenated components. So a Label Set in this scenario would 
>>consist of say 'p' sets each consisting of 'm' sets of 'n' labels. Such a 
>>Label Set cannot be encoded using the object/TLV structure of Label Set 
>>as in "Generalized MPLS - Signalling Functional Description - 
>>Label Set Object can be sent only in WDM scenario where a single 
>>wavelength is requested as a label and the upstream has a restriction on 
>>the usable wavelengths.
>>>From: <mailto:[email-masked]>Zafar Ali
>>>To: <mailto:[email-masked]>Manoj Agiwal ; 
>>><mailto:[email-masked]>'Ccamp (E-mail)
>>>Cc: <mailto:mpls@UU. NET (E-mail)>mpls@UU. NET (E-mail)
>>>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: [email-masked]

===============
Zafar Ali
Cisco Systems
(734) 276-2459
100 S Main St. #200
Ann Arbor, MI 48104.
email: [email-masked]

---

From: Anca Zamfir <[email-masked]>
Date: Wed, 08 May 2002 19:47:51 -0400

Trying to find the answer to the original question.
If a node wants to use Label Set to make sure the downstream label has the 
same value as the upstream one, then, I don't see why it cannot fill in the 
Label Set in the same way it fills in the Upstream Label, as described in 
draft-ietf-ccamp-gmpls-sonet-sdh-03.txt, section 3, for the case NVC=n and 
MT=m case. (Theoretically a node could apply this algorithm p times)
A node that receives and chooses to interpret LabelSet would know how to 
interpret its content by looking at the traffic parameters (in particular 
for this example at the NVC and MT values) which would provide a way to 
"decode" the ordered set of SUKLM labels present in Label Set.
I may be wrong, but I think in theory it is possible to use Label Set for 
this case. As others pointed out, not sure how practical it is.

Anca

At 07:04 PM 5/8/2002 -0400, Zafar Ali wrote:
>>semantics are different than Label Set, in the sense that there is one 
>>and only one value, rather than a set that is manipulated end-end
>>
>>Thanks,
>>
>>John
>>
>>>The Label Set Object can't be sent to constrain the downstream label 
>>>when the LSP encoding type is Sonet/SDH. Consider the example where a 
>>>request is sent to downstream with SONET/SDH traffic parameters as NVC=n 
>>>and MT=m. The label expected from the downstream would be 'm' set of 
>>>labels each set consisting of 'n' labels further that identify each of 
>>>the virtual concatenated components. So a Label Set in this scenario 
>>>would consist of say 'p' sets each consisting of 'm' sets of 'n' labels. 
>>>Such a Label Set cannot be encoded using the object/TLV structure of 
>>>Label Set as in "Generalized MPLS - Signalling Functional Description - 
>>other than WDM. Can we, in principle, agree on this or you are aware of 
>>an alternative for the case you mentioned above?