Subject: Re: [mpls-tp] Tandem Connections in MPLS-TP (was RE:Associatedbidirectional transport path requirements)

From: "Maarten Vissers" <[email-masked]>
Date: Mon, 20 Apr 2009 17:13:12 +0200

Shahram,

In VLANs you don't have a OAM flag in the VLAN Tag either. Nonetheless it is
no problem to detect if a frame carries OAM or non-OAM by a MEP or MIP
function. This information is in the Ethertype following the VLAN Tag. A
similar situation is present in MPLS-TP OAM. The ACH following the shim
header carries the OAM indication. For case of LSP OAM, the label_13 header
following the shim header essentially carries the OAM indication.

But it is always a problem to try to extend existing equipment with new
functions that require hardware support. But this is only an issue for a
short period of time. If we however decide to construct the OAM support such
that existing hardware can be resued, but as consequence require to change
the connection (i.e. add a new LSP and modify the existing LSP), then as
soon as new hardware is available we will still have to change the
connection (i.e. new LSP plus modify existing LSP).

But if LSPs would be single-domain and LSP protection is via client
CL-SNCG/I  protection, then there is no need for LSP TCM (see previous email
today) and this issue becomes a don't care.

Regards,
Maarten

-----Original Message-----
From: Shahram Davari [mailto:[email-masked]] 
Sent: zondag 19 april 2009 0:05
To: 'Maarten Vissers'; [email-masked]
Cc: 'MPLS-TP'
Subject: RE: [mpls-tp] Tandem Connections in MPLS-TP (was
RE:Associatedbidirectional transport path requirements)

Hi Maarten,

I don't agree with you. Because due to lack of OAM flag or indicator in the
MPLS shim header, activation of some MEPs in the middle of an LSP is complex
and requires hop-by-hop deep packet inspection, and therefore from HW
perspective existing MPLS routers can't be used to realize it. While nested
LSP could be used on existing MPLS routers to support MPLS-TP.

Regards,
Shahram

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf
Of Maarten Vissers
Sent: April-18-09 1:20 PM
To: [email-masked]
Cc: 'MPLS-TP'
Subject: Re: [mpls-tp] Tandem Connections in MPLS-TP (was
RE:Associatedbidirectional transport path requirements)

Xueqin,

The nested LSP is a more complex solution then TCM. TCM just requires the
activation of some MEPs in the LSP. Nested LSP requires to set up the same
MEP functions plus set up an additional LSP and change the existing LSP.

Regards,
Maarten

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf
Of Xueqin WEI (Shuetsing WEI)
Sent: zaterdag 18 april 2009 8:52
To: Ben Niven-Jenkins
Cc: MPLS-TP
Subject: Re: [mpls-tp] Tandem Connections in MPLS-TP (was
RE:Associatedbidirectional transport path requirements)

Support, I think the nested LSP will be great! Until now, I didn't see any
difference between the nested LSP and TCM on performance monitoring. But the
nested LSP will make the things more easy. I would like select a simple way
to resolve the problem.

Sincerely Yours
Xueqin Wei (Shuetsing Wei)

Fiberhome Telecommunication Technologies Co.,Ltd.,
2009-04-18  14:48:51

==================== Following is your email=====================
Subject:Re: [mpls-tp] Tandem Connections in MPLS-TP (was RE:
Associatedbidirectional transport path requirements)
Sent：2009-04-17 17:17:31
From:Ben Niven-Jenkins
To:BUSI ITALO; Adrian Farrel; Alexander Vainshtein CC to:mpls-tp

>Italo,
>
>On 17/04/2009 09:34, "BUSI ITALO" <[email-masked]> wrote:
>> The JWT agreement is to bring the ITU-T transport requirements in 
>> IETF to extend the MPLS architecture to meet them in a way that is 
>> compatible, consistent and coherent with existing IETF architecture.
>
>So I took a look at the JWT report. It says (slide 16)
>
>" Service Providers want LSPs/PWEs to be able to be managed at the 
>different nested levels seamlessly (path, segment, multiple segments)
>    aka Tandem Connection Monitoring (TCM), this is used for example 
>when a LSP/PWE crosses multiple administrations"
>
>IMO the requirement is to be able to monitor parts of a path as well as 
>the end to end path. There are many ways to solve that requirement, one 
>of which is the creation of nested LSPs, one per level of monitoring 
>required (my understanding of how TCM works).
>
>I think the real discussion is therefore is the requirement to monitor 
>different components of an end to end path or is the requirement that 
>such monitoring MUST be achieved using nested LSPs?
>
>As an example PW technology today allows end to end and per segment 
>monitoring but it does not achieve it using nested PWs or PW levels.
>
>Ben
>
>_______________________________________________
>mpls-tp mailing list
>[email-masked]
>https://www.ietf.org/mailman/listinfo/mpls-tp
>

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