Subject: [manet] Highest priority flow in DiffServ model

From: "Shaliza Wahab" <[email-masked]>
Date: Fri, 26 Aug 2005 10:11:54 +0100

Dear all,

I just wonder whether in DiffServ model, there is only ONE highest priority flow (Expedited Forwarding) no matter how many high priority flows go into the network? Are the other high priority flows will be treated as AF?

Anybody have the answer?

Thank you very much.

Shaliza Hayati A.Wahab
Department of Computing Science
University of Glasgow
G12 8RZ Glasgo
United Kingdom
_______________________________________________
manet mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/manet

---

From: "Frye, Robert J \(US SSA\)" <[email-masked]>
Date: Fri, 26 Aug 2005 07:22:03 -0400

Shaliza,

You can have as many Expedited Forwarding / High Priority flows as you
want.  However, the point of DiffServ & other QoS approaches is that
ultimately network & processing bandwidth is limited - these define what
should be done when the limit is reached.  With an over-saturated
link/device, some things will get delayed or discarded; having more than
one flow as high priority means that you are giving more traffic the EF
priority treatment and less AF/BE traffic will get thru.  At some point,
if High Priority traffic exceeds the capacity of the router
(/switch/link/...) - particularly if "everything" is marked High
Priority - then some of THAT traffic will get delayed/discarded, almost
completely voiding the meaning and usefulness of marking traffic High
Priority.  (I say "almost" because at that point no AF/BE traffic will
get thru, at least you have limited your traffic load to that which is
deemed High Priority.)

If bandwidth were infinite and processing time was truly instantaneous,
there would be no need for QoS.  Everything would always get through
with no queuing, buffering or delay.

Rob Frye

BAE SYSTEMS

CNIR

11487 Sunset Hills Road

Reston, VA 20190

(v)703-668-4520

(m)571-331-2846

(e)[email-masked]

  _____  

From: [email-masked] [mailto:[email-masked]] On Behalf
Of Shaliza Wahab
Sent: Friday, August 26, 2005 5:12 AM
To: [email-masked]
Subject: [manet] Highest priority flow in DiffServ model

Dear all,

I just wonder whether in DiffServ model, there is only ONE highest
priority flow (Expedited Forwarding) no matter how many high priority
flows go into the network? Are the other high priority flows will be
treated as AF?

Anybody have the answer?

Thank you very much.

Shaliza Hayati A.Wahab

---

From: "Roy, Radhika \(AEAD\)" <[email-masked]>
Date: Fri, 26 Aug 2005 08:15:57 -0400

Hi, Robert and all:
 
You are right.
 
I believe that the real question is this: What do we do to maintain the appropriate QOS levels for all flows over the DiffServ network with finite bandwidth/resources?
 
The answer can be some where else. For example, we can have entities like bandwidth broker that will work behind the scene to know the health of the network monitoring/collecting statistics/measuring all the traffic that goes over the network. Then this entity (or entities) will instruct each node/router what levels need to be attached for each flow.
 
Are there any other mechanisms to address the leveling issues of each flow over the DiffServ network with finite resources to maintain the appropriate levels QOS for all flows?
 
Best regards,
 
Radhika R. Roy

________________________________

From: [email-masked] on behalf of Frye, Robert J (US SSA)
Sent: Fri 8/26/2005 7:22 AM
To: [email-masked]
Subject: RE: [manet] Highest priority flow in DiffServ model

Shaliza,

You can have as many Expedited Forwarding / High Priority flows as you want.  However, the point of DiffServ & other QoS approaches is that ultimately network & processing bandwidth is limited - these define what should be done when the limit is reached.  With an over-saturated link/device, some things will get delayed or discarded; having more than one flow as high priority means that you are giving more traffic the EF priority treatment and less AF/BE traffic will get thru.  At some point, if High Priority traffic exceeds the capacity of the router (/switch/link/...) - particularly if "everything" is marked High Priority - then some of THAT traffic will get delayed/discarded, almost completely voiding the meaning and usefulness of marking traffic High Priority.  (I say "almost" because at that point no AF/BE traffic will get thru, at least you have limited your traffic load to that which is deemed High Priority.)

If bandwidth were infinite and processing time was truly instantaneous, there would be no need for QoS.  Everything would always get through with no queuing, buffering or delay.

Rob Frye

BAE SYSTEMS

CNIR

11487 Sunset Hills Road

Reston, VA 20190

(v)703-668-4520

(m)571-331-2846

________________________________

From: [email-masked] [mailto:[email-masked]] On Behalf Of Shaliza Wahab
Sent: Friday, August 26, 2005 5:12 AM
To: [email-masked]
Subject: [manet] Highest priority flow in DiffServ model

Dear all,

Anybody have the answer?

Thank you very much.

Shaliza Hayati A.Wahab

---

From: "Roy, Radhika \(AEAD\)" <[email-masked]>
Date: Tue, 30 Aug 2005 15:11:19 -0400

Hi, Marshall:

It is good question.

MANET is used in peer-to-peer (ground-to-ground links, air-to-air links)
communications environments. The use of multicast is not so important as
there seems to be inadequate support of MANET-enabled multicast
equipment. 

However, in many situations, multicast will also be used if it is
possible to do so in using emerging technologies. In other words,
necessity for multicast is there in MANET-based peer-to-peer
environments.

Best regards,
Radhika R. Roy

> 5. For multicast in MANET environment, there are a lot of other things
need
> to be taken care of. 
 
If I may ask, how important is multicast to your worldwide network ? Is
this
something that you rate as very important for Manet ?

Regards
Marshall Eubanks

> Anyway, these are couple of observations as inputs to stimulate
discussions.