Re: [CCAMP] OSPF-TE extensions for G.709 OTN draft submitted: draft-ashok-ccamp-gmpls-ospf-g709-01

[[e-mail]]

Hi Pietro,

For your following statement, please refer to the liaison from ITU-T Q12. 
Operator do need the multi stage multiplexing. It focuses on how you 
provide the multi stage multiplexing capability in low cost. 
I don't agree that any routing extension drafts can force operator to use 
multi-stage multiplexing. But you have to provide a method to represent 
the multi-stage capability based on the deployed network.
Termination and switching capabilities could not be understood. I don't 
see any text in draft-ceccarelli-ccamp-gmpls-ospf-g709-04. Could you give 
any example about how to use it?
 
4) Differentiation between termination and switching capabilities is a 
requirement contained in the framework document. The differentiation 
allows an operator
to engineer freely its network keeping into account capabilities offered 
by current technology. Current technology allows switching only a stage at 
once in the matrix.
Of course this can be overcome with very costly muxponder boards that by 
the way could have limitations related to which containers can be 
terminated and which can be
only adapted and sent to matrix for switching. In general a routing 
specification must not force an operator to use costly solutions 
(multi-stage multiplexing) 
in order to operate the network. As a consequence the routing 
specification must provide the means to allow manage the current 
technology indicating clearly which are the capabilities of each interface 
in terms of terminations and switching. 

Xihua Fu




"GRANDI, PIETRO VITTORIO (PIETRO VITTORIO)" 
<[e-mail]> 
·¢¼þÈË:  [e-mail]
2010-10-28 ÏÂÎç 04:30

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Rajan Rao <[e-mail]>
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"[e-mail]" <[e-mail]>, Snigdho Bardalai 
<[e-mail]>, "Ong, Lyndon" <[e-mail]>, Khuzema 
Pithewan <[e-mail]>, "[e-mail]" 
<[e-mail]>
Ö÷Ìâ
Re: [CCAMP] OSPF-TE extensions for G.709 OTN draft submitted: 
draft-ashok-ccamp-gmpls-ospf-g709-01






Hello all,
 
some considerations.
 
1) Draft Ashok states that 
 
                                                 Max LSP Bandwidth 
 
      Number of OPU TSs =      -------------------------
 
                                                  Min LSP Bandwidth
 
This means that the MIN LSP Bandwidth is always set to the nominal size of 
1 TS.
So it can have only two values 1.25 and 2.5 Gbit/s.
The min LSP bandwidth for IETF should instead provide the minimum 
switching capability. (see RFC4202)
 
With the above relationship it seems that a NE that supporting ODU1 and 
higher rate containers
and exporting interfaces with TS size = 1.25 Gbit/s should always declare 
a Min LSP Bandwidth = to 1.25Gbit/s 
that is not corresponding to a supported switching capability.
 
This behavior is absolutely independent from the fact that ODU-flex is 
supported or not. 
 
2)      Snip:
 
¡°Not clear what the issue is.  We have listed 2 approaches in the slides 
sent out yesterday. To reiterate the case where ODUflex is not supported:
 With  backward compatibility option, the ODUflex goes in to a separate 
sub¨CTLV within SCCI. If ODUflex is not supported on a link, this sub-TLV 
will not be included; i.e, ISCD::Max-LSP-BW is not used for ODUflex & 
doesn¡¯t become zero.¡±
 
We would like first to observe that the ashok draft does not report this 
specific behavior. Secondary
we would make note that with this approach the MAX-LSP bandwidth in any 
case should be interpreted differently
when the ODU-flex capacity is exhausted. 
If you think to a bundle link with ODU-flex capacity, then when
UDU-flex capacity is available the MAX-LSP bandwidth is used in a certain 
way whereas when the ODU-flex capacity is exhausted the
ODU-flex TLV is no more advertised and MAX-LSP bandwidth behavior is 
different.
we do not see a reason that motivates the introduction of this kind of 
complication in routing.
 
3)      Snip:
Thirdly, it can not support priority flexibility, so it is not efficient 
from the routing scalability perspective. 
[Rajan] {
The whole idea is to stay with the GMPLS architecture already in place. 
The technology specific extensions should go into SCSI. This has been done 
successfully for SONET/SDH case (Ref to examples in RFC 4202). Do not see 
a reason to deviation from the original GMPLS model.
}
 
The original idea for GMPLS has been already discussed in the frame work 
document draft-ietf-ccamp-gmpls-g709-framework-03. The framework is the 
only
reference for requirements that have to be supported. Moreover, as 
required by CCAMP chair an example of the difference in efficiency between 
the original IETF format
and the new format is shown in the  draft 
draft-bccdg-ccamp-gmpls-ospf-agnostic.  
 
4)      Differentiation between termination and switching capabilities is 
a requirement contained in the framework document. The differentiation 
allows an operator
to engineer freely its network keeping into account capabilities offered 
by current technology. Current technology allows switching only a stage at 
once in the matrix.
Of course this can be overcome with very costly muxponder boards that by 
the way could have limitations related to which containers can be 
terminated and which can be
only adapted and sent to matrix for switching. In general a routing 
specification must not force an operator to use costly solutions 
(multi-stage multiplexing) 
in order to operate the network. As a consequence the routing 
specification must provide the means to allow manage the current 
technology indicating clearly which are the capabilities of each interface 
in terms of terminations and switching. 
 
Pietro & Sergio
 
============================================ 
Pietro Vittorio Grandi 
Terrestrial Optics Unit -  System Architecture 
Alcatel-Lucent Vimercate (Italy) 
Tel: [phone] 
Mail: [e-mail] 
============================================ 
Put your hand on a hot stove for a minute, and it seems like an hour. 
Sit with a pretty girl for an hour, and it seems like a  minute. That's 
relativity. 
(A. Einstein) 

From: [e-mail] [mailto:[e-mail]] On Behalf Of 
Rajan Rao
Sent: marted¨¬ 26 ottobre 2010 21.15
To: Fatai Zhang; Daniele Ceccarelli
Cc: [e-mail]; Snigdho Bardalai; Ong, Lyndon; Khuzema Pithewan; 
[e-mail]
Subject: Re: [CCAMP] OSPF-TE extensions for G.709 OTN draft submitted: 
draft-ashok-ccamp-gmpls-ospf-g709-01
 
Fatai,
 
Please see response inline, within { }
 
Thanks
Rajan
 
From: Fatai Zhang [mailto:[e-mail]] 
Sent: Tuesday, October 26, 2010 5:11 AM
To: Rajan Rao; Daniele Ceccarelli
Cc: Ong, Lyndon; [e-mail]
Subject: Re: [CCAMP] OSPF-TE extensions for G.709 OTN draft submitted: 
draft-ashok-ccamp-gmpls-ospf-g709-01
 
Hi Rajan,
 
You said there are three differences between two drafts. Now, we are 
coming much closer that there "may" be only one difference (i.e., backward 
compatibility) after Daniele gave some clarifications.
 
Your draft introduces a new sub-TLV SCSI and [draft-ceccarelli] introduces 
Generalized-ISCD sub-TLV, so I think they have the same backward 
compatibility, although it seems like that your draft "could" support 
backward compatibility. 
 
Moreover, there are some disadvantages to use the existing ISCD +SCSI. 
Firstly,  as Daniele already pointed it out, it is a big issue to 
advertise that Max LSP bandwidth is 0 in the case of non-ODUflex supported 
for Node B/C, however, for Node A(G.709 V1), it must always advertise a 
meaningful value for the Max LSP bandwidth. 
{Rajan] {
Not clear what the issue is.  We have listed 2 approaches in the slides 
sent out yesterday. To reiterate the case where ODUflex is not supported:
 With  backward compatibility option, the ODUflex goes in to a separate 
sub¨CTLV within SCCI. If ODUflex is not supported on a link, this sub-TLV 
will not be included; i.e, ISCD::Max-LSP-BW is not used for ODUflex & 
doesn¡¯t become zero.
 
Please clarify if you have a different case in mind.
}
 
Secondly, You have changed the meaning of "Minimum LSP Bandwidth", which 
will make the path computation messed. Assume OTU2 interface that supports 
ODU2 switching only (an example in your draft), in this case, according to 
the regular routing process, it will make the routing path computation 
function to understand that it can support ODU0 LSP. 
[Rajan] {
No, we have not changed the meaning of ¡°Minimum LSP BW¡±.   Please 
elaborate on what is messed. 
Following RFC 4202/4201 meaning, the example you have listed works as 
follows:
 
MinLSP-BW = ODU1  ( G.709-v1 supports 2.5G)
MaxLSP-BW = ODU2  ( Min(unreserved-BW, configured Max LSP size)  as per 
RFC 4202)
 
If you are computing path for an ODU0 connection, the rule would be
 
Odu0-LSP-BW >= MinLSP-BW && <= MaxLSP-BW 
 
The computation fails for the above.   Where is it messed? Please provide 
a concrete example.
}
 
Thirdly, it can not support priority flexibility, so it is not efficient 
from the routing scalability perspective. 
[Rajan] {
The whole idea is to stay with the GMPLS architecture already in place. 
The technology specific extensions should go into SCSI. This has been done 
successfully for SONET/SDH case (Ref to examples in RFC 4202). Do not see 
a reason to deviation from the original GMPLS model.
}
 
Fourth, it can not differentiate termination and swiching capability for 
your darft.
 [Rajan] {
We do not see a need to advertise this info.  We need to understand the 
use cases requiring this.  Are T/S bits addressing HW limitations?
}
 
I am trying to recall more reasons why we need to use a new sub-TLV rather 
than the existing TLV, because we had lots of discussion before IETF78th 
meeting through mailing list and F2F, but it is a little difficult for me 
to dig more things from my memory at this moment, :-)~~~~
 [Rajan] {
Please list the justifications for changing original GMPLS model.
}
Best Regards
 
Fatai
 
----- Original Message ----- 
From: Rajan Rao 
To: Daniele Ceccarelli 
Cc: Ong, Lyndon ; [e-mail] 
Sent: Tuesday, October 26, 2010 7:13 AM
Subject: Re: [CCAMP] OSPF-TE extensions for G.709 OTN draft submitted: 
draft-ashok-ccamp-gmpls-ospf-g709-01
 
Daniele,
 
Please see response inline, within { }. 
 
Thanks
Rajan
 
-----Original Message-----
From: Daniele Ceccarelli [mailto:[e-mail]] 
Sent: Friday, October 22, 2010 6:49 AM
To: Rajan Rao
Cc: Ong, Lyndon; [e-mail]
Subject: RE: [CCAMP] OSPF-TE extensions for G.709 OTN draft submitted: 
draft-ashok-ccamp-gmpls-ospf-g709-01
 
Hi Rajan,
 
Just a couple of comments on backward compatibility and bandwidth 
advertisement.
 
- Backward compatibility: no ODU advertising is definded in RFC 4202/4203, 
so i believe there are no backward compatibility issues.
 
 
[Rajan]  { 
Agree there is no ODU advertisement defined. The need to address backwards 
compatibility depends on the following: 
 
 1) are there RFC-4328 based deployments?
 2) If so, what do they use for BW advertisement?
 
Our fair guess is that ISCD is used for this as per RFC 4202/4203. 
 
There are 2 ways to address the compatibility issue ¨C either support or 
don¡¯t support. Based on the WG agreement we could go either way without 
breaking the model we have proposed. Please refer to attached slides for 
details.
 
}
 
Moreover in draft-ashok-ccamp-gmpls-ospf-g709 the MAX LSP bandwidth fields 
of the ISCD are used for unreserved bandwidth advertisement, this is a 
backward compatibility issue in my opinion. It states that:
 
      "Encoding of Max LSP Bandwidth is as follows:
       Max LSP Bandwidth = Unreserved-TS-Count x TS-Nominal-Rate"
 
[Rajan]  { 
 
The unit here is in Bytes/sec. The description above (& in our draft) 
-    shows that nominal rate is dependent on specific ODU layer in 
question. 
-    shows how Max LSP bandwidth number is derived at the advertising 
node.
}
 
Moreover it states:
 
      "If the interface does not support ODU-flex service, 
      this value should be coded as zero".
 
But advertising max LSP bandwidth = 0 means discarding such link in the 
path computation process.
 
[Rajan] {
Good question & very valid. I think you are bringing up a scenario where 
ODUflex is not supported but backward compatibility is required.
 
What we need here is to separate ODUflex advertisement from 
ISCD::Max-LSP-BW. This can be easily accomplished with a sub-TLV for 
ODUflex signal type in our model. BW in bytes/sec, of course.  Please 
refer to attached slides for details.
 
}
 
- Bandwidth advertisement: in the -04 version of our draft the bandwidth 
is advertised as follows:
 
    - Unreserved bandwidth for fixed container in number of containers
    - Unreserved bandwidth for oduflex in Bytes/sec
    - Max LSP bandwidth in Bytes/sec.
 
[Rajan] {
We believe advertising the number of containers is the right approach. 
This is exactly the proposal we have in our draft. Good to see that you 
have moved away from TS approach which had serious limitations.
 
}
 
Advertising the unreserved bandwidth in number of containers is the most 
suitable way for fixed containers (ODUk) but doesn't work with ODUflex.
 
[Rajan] {
 
 The ODUflex uses bytes/sec in our draft.  There is no disagreement here.
 
} 
BR
 
The authors
 
-----Original Message-----
From: [e-mail] [mailto:[e-mail]] On Behalf Of 
Rajan Rao
Sent: venerd¨¬ 15 ottobre 2010 19.13
To: Ong, Lyndon; [e-mail]
Subject: Re: [CCAMP] OSPF-TE extensions for G.709 OTN draft submitted: 
draft-ashok-ccamp-gmpls-ospf-g709-01
 
Lyndon,
 
Yes, we are aware of the existing draft. There are some fundamental 
differences in the model we have proposed from the existing draft. The key 
differences are the following:
 
1) This draft extends existing ISCD  Vs. defining a new one 
    - addresses backward compatibility issues (RFC 4202)
 
2) ODU containers are advertised instead of #TSs
     - simple path computation
 
3) Path computing node doesn't need to know per link and/or per ODU layer 
TS granularity
     - again, simple & straight forward path computation 
 
Thanks
Rajan
 
-----Original Message-----
From: Ong, Lyndon [mailto:[e-mail]]
Sent: Thursday, October 14, 2010 7:45 AM
To: Rajan Rao; [e-mail]
Subject: RE: [CCAMP] OSPF-TE extensions for G.709 OTN draft submitted: 
draft-ashok-ccamp-gmpls-ospf-g709-01
 
Hi Rajan,
 
Have you looked at draft-ceccarelli-ccamp-gmpls-ospf-g709-03.txt?  It 
would be helpful to understand if your draft is asking for similar 
extensions or different functionality.
 
Thanks,
 
Lyndon
 
 
 
-----Original Message-----
From: [e-mail] [mailto:[e-mail]] On Behalf Of 
Rajan Rao
Sent: Wednesday, October 13, 2010 2:40 PM
To: [e-mail]
Subject: [CCAMP] OSPF-TE extensions for G.709 OTN draft submitted:
draft-ashok-ccamp-gmpls-ospf-g709-01
 
Hi,
 
The following draft has been submitted. Please review. Comments are 
appreciated.
 
https://datatracker.ietf.org/doc/draft-ashok-ccamp-gmpls-ospf-g709/
 
thanks
Authors
 
-----Original Message-----
From: IETF I-D Submission Tool [mailto:[e-mail]]
Sent: Wednesday, October 13, 2010 2:30 PM
To: Rajan Rao
Cc: Snigdho Bardalai; Ashok Kunjidhapatham; Khuzema Pithewan
Subject: New Version Notification for
draft-ashok-ccamp-gmpls-ospf-g709-01 
 
 
A new version of I-D, draft-ashok-ccamp-gmpls-ospf-g709-01.txt has been
successfully submitted by Rajan Rao and posted to the IETF repository.
 
Filename:   draft-ashok-ccamp-gmpls-ospf-g709
Revision:   01
Title:            OSPF TE Extensions for Generalized MPLS (GMPLS) Control
of G.709 Optical Transport Networks
Creation_date:    2010-10-12
WG ID:            Independent Submission
Number_of_pages: 20
 
Abstract:
As OTN network capabilities continue to evolve, there is an increased
need to support GMPLS control for the same. [RFC4328] introduced
GMPLS signaling extensions for supporting the early version of G.709
[G.709-v1]. The basic routing considerations from signaling
perspective is also specified in [RFC4328].
 
The recent revision of ITU-T Recommendation G.709 [G.709-v3] and
[GSUP.43] have introduced new ODU containers (both fixed and
flexible) and additional ODU multiplexing capabilities, enabling
support for optimal service aggregation. 
 
This document describes OSPF protocol extensions to support
Generalized MPLS (GMPLS) control for routing services over the
standardized OTU/ODU containers in support of ODU based TDM
switching. Routing support for Optical Channel Layer switching
(Lambda switching) is not covered in this document.
 
 
 
 
The IETF Secretariat.
 
 
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