Subject: [Adslmib] SHDSL Profiles

From: "Darren Sawatzky" <[email-masked]>
Date: Fri, 12 Apr 2002 09:36:00 +1000

Hi,
 
I am trying to understand how to implement the SHDSL profiles.
 
The SNMP architecture that I am working with is based on RFC2741
(AgentX). That is, we have a bunch of loosely coupled cards (SNMP
sub-agents) that are managed via an SNMP management card.
 
As I see it, the profiles are common to all cards. So, if a user creates
a profile "ABC" then all cards will receive a copy of this profile.
Under normal circumstances this all works fine. However, it is the
border cases that as always cause the grief.
 
We have implemented a TDM system. We configure a number of circuits to
operate over the SHDSL spans. We only allow the circuit where the
profile used by a span provides sufficient bandwidth to carry the entire
circuit. If the user tries to configure a circuit where there is
insufficient bandwidth, it is rejected. Similarly, if the user tries to
change the data rate of a span (through its profile) to less than that
required by the configured circuits, the change is rejected.
 
When changing the profile, RFC2741 provides an 'undo' that can be used
to handle the case where one span (on card A) allows the rate to be
changed while another span (card B) doesn't. However, if the profile is
changed while a card is 'offline' and then it comes 'online' it is
configured with this new profile that specifies a line rate that cannot
carry the configured circuits.
 
Has anyone else come across this sort of problem with profiles before?
This problem comes about because in a TDM application the line rate is
basically a span related parameter (as it defines what a span can carry)
yet it is set through a system wide profile. For packet based
applications, I can see that the profiles would work well.
 
Any thoughts would be appreciated.
 
Cheers
 
Darren Sawatzky
[email-masked] < mailto:[email-masked]> 

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From: "Darren Sawatzky" <[email-masked]>
Date: Fri, 12 Apr 2002 13:24:01 +1000

Thanks for the reply. From what you have said, I think you got the gist
of the problem pretty much spot on.

The RFC doesn't say that span configuration profiles must be assigned
per ifIndex. My understanding is that the whole point of profiles is
that they are shared between spans so as to reduce the amount of
configuration required. Which I think is a great idea.

However, the RFC certainly allows for there to be a span configuration
profile per span. That's about where I got to as well. If we have a
profile per span, then the online/offline problem goes away as well
since the span and profile exist on the same board.

Of course, since we need to have a profile for each span, profiles don't
actually buy us anything so I think for the application I am working on
I need to fold the profile & span table into a single proprietary table
and limit the use of the RFC MIB for statistics and the like.

Thanks again for the reply.

Cheers,

Darren Sawatzky.

-----Original Message-----
From: Bob Ray [mailto:[email-masked]] 
Sent: Friday, 12 April 2002 12:06 PM
To: Darren Sawatzky
Subject: RE: [Adslmib] SHDSL Profiles

I may not understand your question(s), but here goes:

Span configuration profiles are assigned per ifIndex, which means
a user can assign profile "ABC" to one card (G.shdsl interface), and
profile "DEF" to another.  In the same chassis.

For those cases where an interface is "offline", has it's configuration
changed, then comes "online" in a state that doesn't support the
application, I would suggest you generate a proprietary notification...

Regards,
Bob Ray