Subject: The defination of QoS in MANET

From: Kui Wu <[email-masked]>
Date: Wed, 1 Mar 2000 14:12:42 -0700 (MST)

Hi all:

It seems that the meaning of QoS in MANET is not clear. Because
of the dynamic topology, the traditional meaning that some performance
metrics(such as bandwidth,end-to-end delay) must be guaranteed once a
request is accepted is no longer true in MANET. In some senses, we can
not guarantee any performance constraint because of inevitable link
breakage. In MANET, after a service is accepted with QoS requirement, the
network system will "try its best" to satisfy the performance requirement. 
So the question is what is the meaning of "try its best" here?

In addition, the Block Rate, which is used to evaluate the performance of
a QoS routing protocol, can not totally represent the goodness of the
protocol, thinking of the situation that the block rate is low but  the
services can not be implemented after accepted. What kind of criteria
should be added to evaluate the performance of QoS routing in MANET?

Hopefully you can give your understanding of QoS in MANET.

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From: campbell <[email-masked]>
Date: Wed, 01 Mar 2000 19:59:26 -0500

Kui:

Kui Wu wrote:
> What kind of criteria

I would argue the opposite:

  Keep the routing simple, light weight and fast.

Don't burden it with more that the typical state of non
QOS routing solutions found in wireline e.g., single metric delay,
shortest path. 

There are good reasons to have a
separation of routing, signaling and forwarding in MANET.

Let me explain my bias:

There has been a growing amount of work in the area of 
QOS routing for fixed networks. 

Here the routing protocols inter work with resource management to
establish paths 
through the network that meet end-to-end QOS requirements 
(i.e., delay, bandwidth, possibly multi-metrics demands). 
(There are lots of state (stale state for example) and
complexity issue here that I will step over.)

In this case there is a certain level of integration of resource 
management and routing. One could apply such an approach to MANET 
routing protocols given that the time scales over which new routes 
are computed is much faster than traditionally found in the case 
of routing in fixed infrastructures. 

While I believe this a promising approach (see the CEDAR as an example) 
- and should be investigated - I note that the 
time scales over which session (flows, microflows) setup and routing 
(i.e., computing new routes) operate are distinct and 
functionally independent tasks. 

Therefore, I believe that signaling, resource management 
and routing should be modeled independently in the network architecture. 

(Of course I am bias because our work on INSIGNIA. We have
implemented INSIGNIA with AODV, DSR and TORA and show
improved performance for TCP and UDP tarffic with these
non QOS routing protocols. We will release the NS
code for this soon which uses Dave J's ns extensions.
The performance looks good for a variety of mobility
and network loads.)

So my spin is that I consider that MANET routing protocol should not be 
burdened with the integration of QOS functionality (as in
the case of CEDAR - I'm sure CEDAR guys will forgive me
for pointing to their protocol as an example of how I
would do routing in MANET) that may be tailored 
toward specific QOS models.  Of
course if the routing scheme does QOS (which I am against)
then INSIGNIA would just do even better. 
I just advise against it as a general approach
for doing QOS in MANET.

Rather, I argue that it is better to maintain 
a clean separation between routing, signaling 
and forwarding. Each of these architectural components are rather 
different in the algorithms they implement and the time scales 
over which they operate. 

The INSIGNIA approach develops QOS framework that you 
can 'pluggin" a wide variety of routing protocols (e.g., CEDAR). 
You can even use INSIGNIA across and between different 
MANET domains and do QOS. 

In this case, resource reservation and signaling protocol will be 
capable of inter working with any number of routing protocols to 
provide end-to-end QOS support. 

For example INSIGNIA provides operational transparency with AODV, 
DSR and TORA which shows the nice quality of these
routing protocols to do there job in hairy environments.

Different MANET routing protocols 
clearly perform differently  in response to topology changes 
while the QOS framework should attempts to maintain end-to-end 
service quality. We see this from our ns simulations.

I'm off on a tangent here. Forgive me.....

Andrew

--
Andrew
http://comet.columbia.edu/~campbell

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From: campbell <[email-masked]>
Date: Wed, 01 Mar 2000 21:15:57 -0500

Ophs.

campbell wrote:
 
> would do routing in MANET)
       
should have read:

(as in the case of CEDAR - I'm sure CEDAR guys will forgive me
for pointing to their protocol as an example of how I
would *not* do routing in MANET)

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From: Joe Macker <[email-masked]>
Date: Thu, 02 Mar 2000 10:27:30 -0500

Andrew:

Thank you for your considered response.
I agreed that we not overburden the present task at hand.

At present manet is not advocating any particular QoS approach whether
layered or integrated ( this is a longer term issue than basic routing
approaches that work).

-Joe

>  Keep the routing simple, light weight and fast.

I agree this is the first term order of business.