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RE: Reducing Usenet Bandwidth

  • From: Vadim Antonov
  • Date: Fri Feb 08 17:49:49 2002


On Fri, 8 Feb 2002, Deepak Jain wrote:

>>   Another area which needs improvement is making L2
>> 	switches similarly aware of community TOS in IP packets.
> 
> Why would an L2 switch need or even want to be aware of TOS? Wouldn't this
> be a Class 3/4..7 issue? If community TOS is supported, those guys that
> would benefit from awareness of it in their internal network would address
> this at a higher level switch I'd think.

Well, maybe, but L2 switches do queueing and drops as well, so there 
should be some way to indicate which packets to drop, and which to keep.
This means that they should be able to look deeper inside frames to 
extract information for frame classification.

(Of course, a cleaner architecture would simply map L3 TOS into some L2 
TOS bits at the originating hosts, but this just didn't happen...)

One may argue that L2 switches typically are not bottlenecks, and the
Internet access circuits effectively limit Ethernet utilization for the
exterior traffic.  However, there's a potential class of applications in
clustered community computing (quite a lot of scientfic simulations,
actually) which can generate very high levels of intra-cluster traffic.
 
> I took your suggestion as a "best effort" below "normal" effort for
> "community" TOS. I could be mistaken.

That is exactly what i had in mind.
 
--vadim





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