Subject: Re: Clarification on PE native/PW signaling behavior

From: "Mustapha Aissaoui" <[email-masked]>
Date: 21 Oct 2002 09:22:51 -0400

Chris,

Chris Metz wrote:

> Section 7.5 states then goes on to say: "..it is desirable that the
>     PEs participate as little as possible in the signaling and
>     maintenance of the native services.  This principle should not,
>     however, override the need to satisfactorily emulate the native
>     service..."
>
> If the emulated service is a switched VC type (e.g. ATM SVC) between two
> CE's, then some implementations may signal the local AC, remote AC and PW
> in realtime. PE participation in the signaling of the emulated service is
> thus unavoidable. However to avoid any complex signaling interworking
> scenarios, I think it should be possible to opaquely transport native
> signaling elements in PW signaling messages without violating the
> principles of minimum intervention.
>
> Is that a fair statement?

Another alternative is to make sure that the native signaling messages travel
over the PSN tunnel using a dedicated PW. This does not require that native
signaling messages be encapsulated in a PW signaling message. I think both
options should be allowed.

---

From: Chris Metz <[email-masked]>
Date: Mon, 21 Oct 2002 19:02:04 -0400

Mustapha-
Below, thanks ...

>options should be allowed.

Understand that one approach is to "bit haul" native signaling content in 
PW signaling messages. This may require TLV extensions to handle this but 
only adds/deletes PW state upon native signaling message appearance at the 
PE and largely emulates the in-band signaling paradigm.

A dedicated PW requires apriori provisioning of the signaling PW and 
emulates out-of-band signaling. It would also mean the PE must steer native 
signaling messages into the special signaling PW. I would think this is 
okay as long as the signaling PW state on the PE  is indistinguishable from 
any other PW state (e.g. does not use a special label value).

Cheers ...

---

From: "Mustapha Aissaoui" <[email-masked]>
Date: 22 Oct 2002 10:16:11 -0400

Hello Chris,

> any other PW state (e.g. does not use a special label value).

yes, it is reasonable to assume that the signaling PW state is indistinguishable
from a user-plane PW state. Once the signaling channel is provisioned, PWs can be
set up on the fly when a native call set up message arrives at the PE.

Though, I am not sure why this would be an emulation of out-of-band signaling?
With reference to the PSN tunnel, this is still inband signaling.

Regards,
Mustapha.