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

["Thomas D. Nadeau" <[e-mail]>]

    I  agree with Andy’s assertion. This service provider’s experience is
that making the CW mandatory going forward (and hopefully retrofitting
existing PW protocol specs) would improve implementation interoperability.

    --Tom



On 6/30/10 11:22 PM, "Luca Martini" <[e-mail]> wrote:

> Andy,
> 
> 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.
> 
> 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.
> 
> 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.
> 
> Luca
> 
> 
> 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]>
>> <mailto:[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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