Subject: Re: Private Group ID

From: Danny McPherson <[email-masked]>
Date: Thu, 01 Feb 2001 09:55:17 -0700

> How about some proposed text about what the VPN-ID would be used for
> with L2TP? The biggest complaint about the Private Group ID is its
> fairly loose application definition. RFC 2764's definition of a VPN-ID
> is somewhat ambiguous to me as well.

Well, I'd personally prefer that it remain loose, as it provides 
more flexibility to the implementor and network operator.  

o It's primary use would be to associate a session or set 
  of sessions with a particular VPN (or susbscriber).  This 
  could be used for lots of things.

o It could be included in a MIB to uniquely identify a session 
  or group of sessiond for management purposes.

o It use could be considered somewhat synonymous to Section 
  5.3.1 of RFC 2764.

o It could also be used to associate a route with a particular
  VPN, perhaps something akin to RFC 2547s Route Distinguisher.

I guess I could go on, but I'm not attempting to scope it to 
anything in particular, as it could be used for a number of 
other things as well.

So, any thoughts?

-danny

---

From: "W. Mark Townsley" <[email-masked]>
Date: Thu, 01 Feb 2001 16:25:46 -0500

> anything in particular, as it could be used for a number of

Here is the problem:

Vendor X uses the ID for one purpose, Vendor Y uses it for another.
Vendor X explains its usage of the ID to a customer. Since the ID is
within a standard, the customer expects that Vendor Y (and every other
vendor) uses it for the same purpose when this is not the case.
Confusion mounts.

If it is stricly for one of the items mentioned above, particularly
logging information as in the MIB bullet, I don't see a problem. But,
once you begin tying it to deeper functionality, we'd better be sure
that is a type of functionality we don't mind identifying as necessary
for any compliant L2TP product (or at the very least a statement to the
affect of, "If the implmentation supports foo, then the VPN ID MAY be
used to ..., otherwise it is for logging purposes only...."). Otherwise,
the customer is easily confused and nobody wins.

I'm not ruling it out, I am just stating the potential problems and why
I think that a strict definition of its intent is better than allowing
it to be a free form field for any purpose. 

- Mark