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

[Giles Heron <[e-mail]>]

Not sure I agree.

Many CPs have deployed PWs with no CW.   Adding a CW to all packets just to
enable occasional OAM messages seems like overkill.

But the downside of adding GAL is that it’s a fourth OAM mode for PWEs (back
to your point about interoperability).  Too many options!

Giles

On 01/07/2010 12:14, "Tom Nadeau" <[e-mail]> wrote:

> 
>     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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