Subject: Re: Scaling of management plane for Diffserv (was RE: [Diffserv] RE: A few comments for draft-ietf-diffserv-mib-09.txt)

From: Brian E Carpenter <[email-masked]>
Date: Thu, 19 Apr 2001 14:14:15 -0500

Faye,

This addresses your other message as well.

Firstly the core. There won't be thousands of data paths through core routers.
There will be a small number of diffserv traffic aggregates - the whole idea
is to make it scale like NM (N= number of interfaces and M= number of DSCPs).
That's the diffserv model. If you get to thousands, you are trying to recreate 
Intserv using Diffserv and that clearly doesn't scale; the MIB is the least 
of your problems.

Secondly the ISP edge. You will have a few large feeds (either a few large
enterprise customers, or a few aggregated NAS clusters). The scale is
the same as in the core, except that you will have MF classifiers.

Thirdly the campus. I would expect the admission control and MF classification
to be done by each LAN's router - no particular scaling problem. The campus
aggregation router(s) will not see any detail - just a few traffic aggregates
handled by a few BA classifiers.

The only place I see the scaling going to thousands is if, and only if, you
want to do admission control per subscriber on network access servers. And as
I said before, that clearly exceeds the scaling limit of the current MIB.

   Brian

Faye Ly wrote:
> 
> Brian,
> 
> Can you please explain why is that the ISP edge router will support only
> a limited
> number of interfaces??  What about campus edge routers?  Thanks.
> 
> -faye

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---

From: "Faye Ly" <[email-masked]>
Date: Thu, 19 Apr 2001 14:46:34 -0700

Brian,

That was very clear, thank you.  I guess what you are saying is that
each 
router is managed by a different network management tool?  Or is it a
single
NM tool that manages both campus LAN routers and corporate center core 
routers?  Do you still think it will not scale up to thousands of
interfaces?

What about the case where the ILEC is actually the ISP also?  Wouldn't
they
be managing all the edge/core routers using the same network management
tool?  I guess you are trying to say this is out of the scope of the
diffServ
and it should be done in the SNMPCONF?  I am fine with that since a lot
of
the north-bound interfaces will not be SNMP only.  I was hoping too much
I guess!

Thanks.

-faye

-----Original Message-----
From: Brian E Carpenter [mailto:[email-masked]]
Sent: Thursday, April 19, 2001 12:14 PM
To: Faye Ly
Cc: diffserv
Subject: Re: Scaling of management plane for Diffserv (was RE:
[Diffserv] RE: A few comments for draft-ietf-diffserv-mib-09.txt)

Faye,

Firstly the core. There won't be thousands of data paths through core
routers.
There will be a small number of diffserv traffic aggregates - the whole
idea
is to make it scale like NM (N= number of interfaces and M= number of
DSCPs).
That's the diffserv model. If you get to thousands, you are trying to
recreate 
Intserv using Diffserv and that clearly doesn't scale; the MIB is the
least 
of your problems.

Secondly the ISP edge. You will have a few large feeds (either a few
large
enterprise customers, or a few aggregated NAS clusters). The scale is
the same as in the core, except that you will have MF classifiers.

Thirdly the campus. I would expect the admission control and MF
classification
to be done by each LAN's router - no particular scaling problem. The
campus
aggregation router(s) will not see any detail - just a few traffic
aggregates
handled by a few BA classifiers.

The only place I see the scaling going to thousands is if, and only if,
you
want to do admission control per subscriber on network access servers.
And as
I said before, that clearly exceeds the scaling limit of the current
MIB.

   Brian

---

From: Fred Baker <[email-masked]>
Date: Fri, 20 Apr 2001 17:04:06 -0700

At 11:31 AM 4/19/2001 -0700, Faye Ly wrote:
>Can you please explain why is that the ISP edge router will support only a 
>limited
>number of interfaces??  What about campus edge routers?

what my ISP customers tell me is that they would like it to be able to 
support a large number of interfaces - the more the merrier, it seems. If 
they can support N access customers (whose line is already a single point 
of failure) with one box instead of ten, they seem to be happy to do so.

They also tell me, and this is where snmpconf comes in, that these access 
contracts often fall into a few categories. For example, if I call Verizon 
and ask for DSL service to my home, they ask me to choose from a short menu 
of DSL contracts they sell. Or if I go as a business to get a leased line 
to their network, they tend to say "what speed, and with what worst case 
latency within our network", and maybe a couple more questions. Anything 
beyond that gets real sticky.

So a DSL access device might support some number of thousands of 
interfaces, but they will fall into a few categories of contract and 
therefore of configuration. At this point, I expect Andrew to chime in and 
say "so they would be configured by describing a "role" for each such 
contract, configuring the router with a set of role templates, and telling 
each interface what role they support. They then derive their configuration 
from the template.