Re: [mpls-tp] [PWE3] Proposal of using GAL for PW

[Huub van Helvoort <[e-mail]>]

Ciao Luca,

You wrote:

> I have to disagree that there was any consensus about this issue.
> If anything , there was consensus that there is no written statement 
> that we must to use the CW in MPLS-TP.

I agree with this.

> At the end we needed more input from service providers that have 
> deployed PWs. The point is not whether there is hardware support for the 
> CW, but whether we even want to use it in many cases where it adds 
> absolutely no value. For example ATM PWs in cell mode , where it add 
> almost 10% overhead with no benefit. Another case where the CW is not 
> useful is the ethernet PW without network link load balancing, where we 
> add 4 bytes to every packet just to occasionally send a status , or OAM 
> message.
> 
> I would like to propose update the rfc5586 to allow the use of the GAL 
> in PWs without the CW.

I  support this

> This makes the use of the GAL very symmetric among PWs and MPLS-TP LSPs. 
> This makes it easy to process by hardware based implementations.

I agree, consistency is very important, it causes less mistakes
in maintaining a network., and also for implementations (HW and SW).

Best regards, Huub.


> Andrew G. Malis wrote:
>> Larry and Feng,
>>
>> This issue has previously been discussed at length by the working
>> group, both at the Anaheim meeting and by email, for example in emails
>> with the subject line "Possible Contradiction re use of GAL in
>> pwe3-static-pw-status". There was rough consensus that for MPLS-TP
>> applications and/or when PW OAM is desired, PW implementations are
>> mature enough (it has been 10 years now, after all) that the time has
>> come to require the implementation of the CW for all PWs, including
>> Ethernet.
>>
>> Cheers,
>> Andy
>>
>> On Wed, Jun 30, 2010 at 6:34 AM, HUANG Feng F
>> <[e-mail]>  wrote:
>>    
>>> it is reasonable to support GAL in MPLS-TP PW OAM, it is more generic, because CW is an option RFC4448 for Ethernet over MPLS.
>>>
>>> 4.6.  The Control Word
>>>
>>> xxxx
>>>
>>>
>>> The features that the control word provides may not be needed for a
>>>    given Ethernet PW.  For example, ECMP may not be present or active on
>>>    a given MPLS network, strict frame sequencing may not be required,
>>>    etc.  If this is the case, the control word provides little value and
>>>    is therefore optional.  Early Ethernet PW implementations have been
>>>    deployed that do not include a control word or the ability to process
>>>    one if present.  To aid in backwards compatibility, future
>>>    implementations MUST be able to send and receive frames without the
>>>    control word present.
>>> xxxx
>>>
>>>
>>>
>>> B.R.
>>> Feng Huang
>>>
>>>
>>> -----Original Message-----
>>> From:[e-mail]  [mailto:[e-mail]] On Behalf Of Larry
>>> Sent: 2010年6月30日 17:38
>>> To:[e-mail];[e-mail]
>>> Cc:[e-mail]
>>> Subject: [PWE3] Proposal of using GAL for PW
>>>
>>> Dear all:
>>>
>>>      In section 4.2 in RFC5586, it is defined that GAL MUST NOT be used with PWs in MPLS-TP. The PWE3 control word [RFC4385] MUST be present when the ACH is used to realize the associated control channel.
>>>      In real application, a lot of MPLS and MPLS-TP equipments do not support control word. It is proposed to use the GAL to identify associated control channel in PW layer.
>>>
>>> Best regards,
>>>
>>>                  Han Li
>>>
>>> ********************************************************************
>>> Han Li, Ph.D
>>> China Mobile Research Institute
>>> Unit 2, 28 Xuanwumenxi Ave, Xuanwu District, Beijing 100053, China
>>> Fax: [phone]
>>> MOBILE: [phone]
>>> ********************************************************************
>>>
>>>      
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>>    
> 
> 
> 
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