Subject: [ANCP] ANCP draft: BRAS behaviour

From: "Kim Hyldgaard \(ST/LMD\)" <[email-masked]>
Date: Mon, 13 Nov 2006 14:00:39 +0100

Hi all,

This is an open question on BRAS behaviour in ANCP scenarios.

I think at least the first topic was discussed in the spring,
but I don't remember if there were any conclusions.
- If so, please enlighten me.

1)
If a DSL line is removed from a DSLAM, the draft states that
the DSLAM should send a port DOWN message to the BRAS.

But in this case the line is actually more than DOWN; it is
completely removed from the system.

How will the BRAS learn that this is no longer a valid line?
Is it removed by some kind of aging timer?
I think a special line state value was discussed to signal this,
but I guess it was never included?

Or... Should the line be removed from the BRAS?

2)
How does the BRAS handle fallback from PTM to ATM?

Will a BRAS see that the ACI is acutally pointing to the same line,
eventhough the ACI differs in "eth" and "atm" + the VPI/VCI or VLAN ID?

I think the draft is a bit vague on this point, but maybe I
just haven't found the section specifying this.

I'd appreciate some comments from anybody with knowledge of
BRAS and ANCP behaviour.

Thanks in advance.

Kind regards
Kim Hyldgaard

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---

From: "Peter Arberg" <[email-masked]>
Date: Mon, 13 Nov 2006 21:44:08 -0800

Hi Kim, 

some comments and answers inline.

> -----Original Message-----
> From: Kim Hyldgaard (ST/LMD) [mailto:[email-masked]] 
> Sent: 13. november 2006 05:01
> To: Sanjay Wadhwa; [email-masked]; [email-masked]
> Subject: [ANCP] ANCP draft: BRAS behaviour
> 
> Hi all,
> 

I don't think we ever reached any conclusion..

> Is it removed by some kind of aging timer?

The BRAS today have no way of learning that a line have been 
deleted from the AN.

There is no aging timer that I'm aware of, the only way I think
you would be able to remove a line from the BRAS is manual 
intervention, and do a "line delete" on the BRAS if such a functionality
is implemented on the BRAS.

> but I guess it was never included?

Yes as far as I remember we did discuss the need to implement and
use a gsmp dead port message, which would be a simple way for the
AN to signal the BRAS to remove a specific ACI from its port database.

But as far as I remember we also at the same time discussed the need
to make a version control of the protocol, so we could move forward
with some of these enhancements without breaking backwards compatibility.

I think it is time to get started with this, and I would like to
make an initial draft of this if people agree on the usability.

As such I think it might be a mistake to keep the gsmp version as 3.1
for ANCP, I would much rather like to see it start at another version
once we reach concensus on the draft, and then everything prior to
this draft is running on the version 3.1.

> eventhough the ACI differs in "eth" and "atm" + the VPI/VCI 

No the BRAS is not suppose to parse the ACI, it is a string
identifier.

What will happen is that the BRAS will get a new port ACI entry in
its port database, and the old one will sit there until it is 
manually deleted (or we create the dead port message :)

> just haven't found the section specifying this.

I have not seen it either, but I think we should add it, but
in my mind it goes hand in hand with the dead port and the version 
control.

cheers,
Peter

---

From: "Kim Hyldgaard \(ST/LMD\)" <[email-masked]>
Date: Tue, 14 Nov 2006 07:08:59 +0100

Hi Peter,

Thanks for your answers.

>>make an initial draft of this if people agree on the usability.

I agree that we need ANCP to handle the situations, and I think it
would be very good with an initial draft on the topic, in order for
us to have something as a basis for further discussions.

Br
Kim

-----Original Message-----
From: Peter Arberg [mailto:[email-masked]] 
Sent: 14. november 2006 06:44
To: Kim Hyldgaard (ST/LMD); 'Sanjay Wadhwa'; [email-masked];
[email-masked]
Subject: RE: [ANCP] ANCP draft: BRAS behaviour

Hi Kim, 

> I think at least the first topic was discussed in the spring, but I 
> don't remember if there were any conclusions.

> 1)
> If a DSL line is removed from a DSLAM, the draft states that the DSLAM

> should send a port DOWN message to the BRAS.
> 
> But in this case the line is actually more than DOWN; it is completely

> removed from the system.

The BRAS today have no way of learning that a line have been deleted
from the AN.

There is no aging timer that I'm aware of, the only way I think you
would be able to remove a line from the BRAS is manual intervention, and
do a "line delete" on the BRAS if such a functionality is implemented on
the BRAS.

But as far as I remember we also at the same time discussed the need
to make a version control of the protocol, so we could move forward
with some of these enhancements without breaking backwards
compatibility.

cheers,
Peter