Re: [PWE3] CW usage in opposite directions for static PWs

Yaakov Stein <yaakov_s@rad.com> Wed, 11 April 2012 07:51 UTC

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From: Yaakov Stein <yaakov_s@rad.com>
To: "stbryant@cisco.com" <stbryant@cisco.com>, "Andrew G. Malis" <amalis@gmail.com>
Thread-Topic: [PWE3] CW usage in opposite directions for static PWs
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Date: Wed, 11 Apr 2012 07:50:59 +0000
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Cc: Lizhong Jin <lizhong.jin@zte.com.cn>, "pwe3@ietf.org" <pwe3@ietf.org>
Subject: Re: [PWE3] CW usage in opposite directions for static PWs
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Stewart

Of course the PWE3 control protocol is clear in enforcing the use of non-use in both directions.
Even there, I do not recall debate on the subject. It was "yeah, I guess that's OK".

In my slide deck a few years back I discussed the state of affairs for other methods of setting up PWs 

I am OK with a decision to enforce the symmetry,
but we need to discuss this and agree on it.
And perhaps there are other parameters that need similar discussion.
For example, can I set up a TDM PW with an E1 in one direction and a T1 in the other ?
What about a raw Ethernet PW in one direction and a tagged one in the opposite direction ?

If this is a general principle (as I suspect many people believe, but I don't recall was ever explicitly stated)
then this should be written up (and the implications considered).

Y(J)S


-----Original Message-----
From: pwe3-bounces@ietf.org [mailto:pwe3-bounces@ietf.org] On Behalf Of Stewart Bryant
Sent: Tuesday, April 10, 2012 19:14
To: Andrew G. Malis
Cc: Lizhong Jin; pwe3@ietf.org; Yaakov Stein
Subject: Re: [PWE3] CW usage in opposite directions for static PWs

On 10/04/2012 17:08, Andrew G. Malis wrote:
> All,
>
> This has been an extremely useful discussion.
>
> <wg chair hat off>
>
> Personally, I don't really see much utility in asymmetric CWs in a PW.
>
> <wg chair hat on>
>
> Once the WG comes to consensus on the issue one way or the other (and 
> I would like to hear some more opinions), we should consider document 
> revisions as necessary to make sure that the consensus is clearly 
> reflected in the RFCs.
>
> Cheers,
> Andy

For LDP signaled PWs, I don't think there is any ambiguity, the CW 
handling is symmetric. Does anyone read it any other way?

Stewart

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