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

On 7/1/10 9:22 AM, "Giles Heron" <giles.heron@gmail.com> wrote:

> 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.
> 
> TOM: The question would be in those cases: do those CPs have multi-vendor
> implementations and how difficult is it for them to handle operational issues
> as well as interoperability of those implementations?  The operators that have
> presented/discussed this at the last PWE3 meeting seemed to voice a resounding
> desire to have a consistent method rather than 3, 4 or N options.
> 
> 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!
> 
> TOM: Precisely the point of requiring one way to do things.  Too many options
> is ok to get the kinks worked out of implementations, but going forward it
> seems better to narrow things as Andy’s original note asserted.
> 
>     --Tom
> 
> 
> 
> Giles
> 
> On 01/07/2010 12:14, "Tom Nadeau" <tom.nadeau@bt.com> 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" <lmartini@cisco.com> 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
>>>> <Feng.f.Huang@alcatel-sbell.com.cn>
>>>> <mailto:Feng.f.Huang@alcatel-sbell.com.cn>  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: pwe3-bounces@ietf.org [mailto:pwe3-bounces@ietf.org] On Behalf Of
>>>>> Larry
>>>>> Sent: 2010年6月30日 17:38
>>>>> To: mpls-tp@ietf.org; pwe3@ietf.org
>>>>> Cc: lihan@chinamobile.com
>>>>> 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: +86 10 63601087
>>>>> MOBILE: 13501093385
>>>>> ********************************************************************
>>>>> 
>>>>>     
>>>>>  
>>>>  
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>>>>   
>>> 
>>> 
>>> 
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>> 
>> 
>> 
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