Subject: [Megaco] Questions about the tman package

From: "Jisu Bhattacharya" <[email-masked]>
Date: Thu, 5 Apr 2007 10:07:29 -0700

Hi guys,

I was reading the tman package as defined by ETSI and now under review as
H.248.53. I have the following questions:

1. Draft H.248.53 makes some suggestions regarding how to map the tman
parameters into ATM and IP based policing protocols. In that section, it
uses either pdr + dvt + M OR sdr + mbs + M. So is it ultimately recommending
either peak-rate policing or sustained-rate policing but NOT
dual-leaky-bucket policing?

2. What are the valid combinations of pdr, sdr, mbs, dvt and pol that GC can
specify? For example, can it only specify pdr and mbs?

3. I see tman/pol is now going to default to OFF in H.248.53. The ETSI doc
does not have a default. Will this cause backward compatibility issues?

Thanks,

Jisu Bhattacharya
Cisco Systems
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---

From: [email-masked]
Date: Fri, 6 Apr 2007 02:46:45 +0200

Jisu,
comments inline.
-Albrecht

                      "Jisu                                                                                                             
                      Bhattacharya"            To:      [email-masked]                                                                 
                      <[email-masked]         cc:                                                                                      
                      m>                       Subject: [Megaco] Questions about the tman package                                       
                                                                                                                                        
                      05.04.2007 19:07                                                                                                  

Hi guys,

1. Draft H.248.53 makes some suggestions regarding how to map the tman
parameters into ATM and IP based policing protocols. In that section, it
uses either pdr + dvt + M OR sdr + mbs + M. So is it ultimately
recommending either peak-rate policing or sustained-rate policing but NOT
dual-leaky-bucket policing?

[ABS] Every property-to-policer parameter mapping is determined by the used
policer algorithm. A general answer on your question is thus not possible
on your generic question. E.g., if you use GBRA according Y.1221 for
traffic policing of IP traffic, then there are single- and dual-LB
algorithms.
So there isn't any ultimative recommendation in H.248.53.

2. What are the valid combinations of pdr, sdr, mbs, dvt and pol that GC
can specify? For example, can it only specify pdr and mbs?

[ABS] It depends which "traffic characteristic(s)" you want to policy, e.g.
peak rate, peak rate & sustainable rate, just packet sizes, etc. There are
many meaningful combinations. The next dependency is again your selected
policer algorithm.

[ABS] Theoretically yes, because ETSI TS 102 333 Annex C was not explicit
on that subject. Practically, when looking at the H.248 profiles in which
tman/1 is used, I don't think so. When tman/1 was transferred to ITU-T
H.248.53, we had to formalize the package according the package template.
The proposal of "OFF" was pending a couple of meetings without any
objections. But there's still a chance to change that in the next SG16
meeting. Please come with a correspondent contribution.
I don't have any strong opinion on that. "ON" or "NONE" might be also
meaningful. Guess "OFF" was considered to be more conservative.

Thanks,

Jisu Bhattacharya
Cisco Systems_______________________________________________
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