Subject: [Diffserv] Meaning of ZeroDotZero in DSMIB

From: Ratnakar Pai <[email-masked]>
Date: Mon, 19 Mar 2001 17:43:06 +0530

Hi,

   Have a doubt about the usage of ZeroDotZero in the  Management Information
   Base for Diffserv architecture . 

 What is the action to be undertaken when ZeroDotZero is encountered? 
 The MIB mentions that it is the end of the Diffserv functionality . What does
  ths mean ?? 

 How do we know what is the next functionality to be applied. 
 For eg. in the case of ingress the functionality may be ip forwarding and in
 the case of egress it may be the dev driver transmit functionality. 

   For example
  On the ingress side :

      The Next Data Path element of the Meter Table is 0.0 , Then after meter
   functionality is executed , should we carry out the normal IP forwarding .
   There is no queuing taking place in this particular case .
 --  
Ratnakar Pai 

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From: Fred Baker <[email-masked]>
Date: Mon, 19 Mar 2001 07:04:33 -0600

I think you answered your own question - on the ingress side, after you 
have applied forwarding and accounting policies related to the ingress 
interface, one would expect you to select an egress interface and routing 
neighbor, and apply the policies related to it.

But the point is not that we know what that process is. The point is that 
it is not specified by diffserv, and therefore beyond the scope of this MIB.

At 05:43 PM 3/19/2001 +0530, Ratnakar Pai wrote:
>Archive: 
>http://www2.ietf.org/mail-archive/working-groups/diffserv/current/maillist.html

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From: Ratnakar Pai <[email-masked]>
Date: Tue, 20 Mar 2001 10:37:31 +0530

Hi,
  do the accounting policies relating to the ingress interface have to be
applied after forwarding(ip forwarding - routing core) or before? This is 
just to clarify the sentence

> neighbor, and apply the policies related to it.

regards,
ratnakar

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From: Fred Baker <[email-masked]>
Date: Tue, 20 Mar 2001 13:25:09 -0600

>just to clarify the sentence

I don't especially care. They need to have the same effect as if the 
ingress diff-serv configuration was applied, forwarding occurred, and then 
the egress diff-serv configuration was applied. That is by no means the way 
it has to be implemented - one could easily imagine implementing the three 
steps in parallel engines, for example. But it should be indistinguishable 
from that, externally.

For example: suppose that you are a service provider. You have a contract 
with customer A that it may send you at most some amount of AF11 traffic, 
and that you will remark any excess as AF12. You also have a contract with 
customer B that, on traffic to it, you will apply certain RED 
characteristics to AF11 traffic in a certain queue and certain other RED 
characteristics (a lower min-threshold) to AF12 traffic. And let's further 
suppose that customers A and B are both serviced from the same router. One 
would expect that customer B might be receiving AF1 traffic from a large 
number of customers, not just from customer A. Likewise, one would expect 
that the ingress configuration for customer A would apply only to its 
traffic; you're not going to commingle traffic from other customers into 
that ingress policy. And the fact that it went through the ingress 
configuration may very well mean that something received as AF11 must be 
remarked, queued, and randomly dropped according to customer B's AF12 
rules. What you have to implement is that correct accounting and correct 
application of policy; to do otherwise would not correctly implement the SLAs.