Subject: RE: [manet] QoS over a wireless Ad Hoc network

From: John Peter Tapsell <[email-masked]>
Date: Wed, 3 Jul 2002 14:42:47 +0100

Harpreet Arora sent me the paper..  I've put it up at
www.cs.man.ac.uk/~tapselj0/paper2.pdf - I hope Harpreet
doesn't mind ..

JohnFlux

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From: John Peter Tapsell <[email-masked]>
Date: Wed, 3 Jul 2002 14:42:47 +0100

JohnFlux

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From: John Peter Tapsell <[email-masked]>
Date: Thu, 4 Jul 2002 11:27:30 +0100

I'm confused.. :)

I thought diffserv was simply each node knowing about priority traffic
so simply queueing that first.. ?  In which case I can't see the difficulty
in doing this in ad-hoc networks?
Were you thinking of intserv ?  Or am I going looney? :)

JohnFlux

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From: "Yasser A. Lotfy" <[email-masked]>
Date: Thu, 04 Jul 2002 10:01:07 -0400

Arora,

I'm very confused here. First, what do you mean the periority depends on the service provider? Who is the service provider for ad-hoc bandwidth? 

Second, What do you mean by your classification of periorities? DiffServ rely on predefined PHB to achieve a PDB (Per Domain Behaviour). This is done by engineering the network with the help of provisioning systems, and human adminstration. How this could be solved for DiffServ is quite a challenge.

I can't claim to have read your paper, I'll read it right now.

Yasser
Carleton U

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From: "Yasser A. Lotfy" <[email-masked]>
Date: Thu, 04 Jul 2002 10:01:07 -0400

Arora,

Yasser
Carleton U

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From: Harpreet Arora <[email-masked]>
Date: Mon, 08 Jul 2002 13:50:03 -0400

Hi Yasser,

>
>I'm very confused here. First, what do you mean the periority depends on the
>service provider? Who is the service provider for ad-hoc bandwidth?

I agree that in an ad hoc network there is no service provider. Well, in that 
case, the problem of providing QoS guarantees in an ad hoc network becomes 
very complex. If there is no one to bill a user for using higher bandwidth, 
everyone in the netwrok wud try to use the maximum bandwidth available. Then 
the classification of traffic into priorities in an ad hoc network makes sense 
only for networks where some users are more powerful than others. For example 
in an ad hoc network formed by laptops in a classroom, the messages from the 
professor can be assigned higher priority than that of students. Or, the 
priorities can be assigned at the application level, which cannot be modified 
by the user. For e.g, an email application always uses best effort traffic, 
and packets of voice application can always be set to receive a certain 
priority.
>
>Second, What do you mean by your classification of periorities? DiffServ rely 
on predefined PHB to achieve a PDB (Per Domain Behaviour). This is done by 
engineering the network with the help of provisioning systems, and human 
adminstration. How this could be solved for DiffServ is quite a challenge.

It is the PHB that provides classification of priorities. The PHBs are defined 
such that traffic of different streams get different priorities within the 
queue and at the schedular. Let me know if I am wrong in my thinking here.

regards,
Harpreet

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From: Harpreet Arora <[email-masked]>
Date: Mon, 08 Jul 2002 13:50:03 -0400

Hi Yasser,

regards,
Harpreet

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From: "Yasser A. Lotfy" <[email-masked]>
Date: Mon, 08 Jul 2002 16:30:29 -0400

Good day Arora,
I believe we went through the same arguments on DiffServ work group. The main assumption you're after is that some traffic is has higher priority (based on user class). But traffic can also be classified based on (traffic type class). There are a long argument around that which ended with setting policies (adminstrator defined), aggregate traffic based on those policies, then police traffic marking. 

Then the second issue of viewing PHB as a priority engine is too simplistic. DiffServ domains need to be engineered using service provisioning policies to reach maximum thoughput. When applying this to a MANET like network, I have many questions as to how to provision policies in a dynamic topology environment?

Yasser 
Carleton University

---------------------------------------------------
Hi Yasser,

>
>I'm very confused here. First, what do you mean the periority 
> depends on the service provider? Who is the service provider 
> for ad-hoc bandwidth?

I agree that in an ad hoc network there is no service provider. Well, in that case, the problem of providing QoS guarantees in an ad hoc network becomes very complex. If there is no one to bill a user for using higher bandwidth, everyone in the netwrok wud try to use the maximum bandwidth available. Then the classification of traffic into priorities in an ad hoc network makes sense only for networks where some users are more powerful than others. For example in an ad hoc network formed by laptops in a classroom, the messages from the 
professor can be assigned higher priority than that of students. Or, the priorities can be assigned at the application level, which cannot be modified by the user. For e.g, an email application always uses best effort traffic, and packets of voice application can always be set to receive a certain priority.
>
>Second, What do you mean by your classification of periorities? 
>DiffServ rely on predefined PHB to achieve a PDB (Per Domain 
>Behaviour). This is done by engineering the network with the 
>help of provisioning systems, and human adminstration. How 
>this could be solved for DiffServ is quite a challenge.

It is the PHB that provides classification of priorities. The PHBs are defined such that traffic of different streams get different priorities within the queue and at the schedular. Let me know if I am wrong in my thinking here.

regards,
Harpreet

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From: "Yasser A. Lotfy" <[email-masked]>
Date: Mon, 08 Jul 2002 16:30:29 -0400

Good day Arora,

Yasser 
Carleton University

regards,
Harpreet