Subject: Re: Updated minutes from IETF 77

From: Raymond Key <[email-masked]>
Date: Thu, 22 Apr 2010 07:55:25 +1000

Hi Nic,

I go through the recently published IETF77 L2VPN minutes and 
would like to follow up on one of your comments.

Extract from minutes under
10) Extension to VPLS for E-Tree
"Nic: This requires a control word, so a box has to support a control word. 
PW mustn't come up if a CW is not supported."

There may be some confusion here. When one PE does not support 
control word, PW can still come up.

Refer to Section 5.2. Control Word (under Backward Compatibility)
For backward compatibility reason, use of Control Word on Ethernet PW
is not mandatory. If the PE on the other end prefers not to use
Control Word or does not support Control Word (which implies such PE
does not support the extension specified in this document), then
Control Word will not be used on the Ethernet PW.
Refer to Appendix A for different Control Word scenarios.
(http://tools.ietf.org/html/draft-key-l2vpn-vpls-etree-02#section-5.2)

Regards,
Raymond Key

> Giles Heron <[email-masked]> wrote:
> 
> Ok - so it'd help if I actually put some content in my email.
> 
> As Simon Delord helpfully pointed out the other day I missed the second 
> half
> of the meeting out when I posted these.
> 
> I've now updated the online minutes:
> 
> http://www.ietf.org/proceedings/10mar/minutes/l2vpn.txt
> 
> Giles

---

From: "Delregno, Christopher N (Nick DelRegno)" <[email-masked]>
Date: Wed, 21 Apr 2010 23:00:38 +0000

Raymond:

>From a purely T-LDP perspective, I agree.  However, if we are relying on
CW to indicate leaf/root and the targeted PE doesn't support CW, then
the ETREE model breaks as I can no longer determine leaf/root and
drop/forward traffic accordingly.  As such, the implementation behavior
when using CW to indicate Leaf/Root MUST NOT allow the CW preference
mismatch to result in an active PW.

Thanks,
Nick

-----Original Message-----
From: Raymond Key [mailto:[email-masked]] 
Sent: Wednesday, April 21, 2010 4:55 PM
To: Delregno, Christopher N (Nick DelRegno)
Cc: [email-masked]
Subject: Re: Updated minutes from IETF 77

Hi Nic,

I go through the recently published IETF77 L2VPN minutes and would like
to follow up on one of your comments.

Extract from minutes under
10) Extension to VPLS for E-Tree
"Nic: This requires a control word, so a box has to support a control
word. 
PW mustn't come up if a CW is not supported."

There may be some confusion here. When one PE does not support control
word, PW can still come up.

Refer to Section 5.2. Control Word (under Backward Compatibility) For
backward compatibility reason, use of Control Word on Ethernet PW is not
mandatory. If the PE on the other end prefers not to use Control Word or
does not support Control Word (which implies such PE does not support
the extension specified in this document), then Control Word will not be
used on the Ethernet PW.
Refer to Appendix A for different Control Word scenarios.
(http://tools.ietf.org/html/draft-key-l2vpn-vpls-etree-02#section-5.2)

Regards,
Raymond Key

> As Simon Delord helpfully pointed out the other day I missed the 
> second half of the meeting out when I posted these.
>