Subject: Re: multiple Tx queues
To: Erik E. Fair <>
From: Nick Hudson <>
List: tech-net
Date: 01/08/2004 08:47:49
[fx: tries not to get on his soap box]

On Wednesday 07 January 2004 10:16 pm, Erik E. Fair wrote:
> At 8:32 -0800 1/7/04, Jason Thorpe wrote:
> >Could utilize packet tags to map IP TOS, maybe?
> I thought the IETF explicitly deprecated the TOS bits a while ago? 
> There was a proposal to reuse at least one of them for a "congestion 
> experienced" bit...

Its now called DSCP see rfc2474 and rfc3260

The congestion stuff appears in rfc3168

> I do remember that the main reason the TOS bits were thought to be 
> silly to implement was that if you really want to support N paths 
> with different TOS parameters to the same destination, you end up 
> (worst case) multiplying the size of the routing table by N for each 
> destination net that has different TOS parameters. Given the pressure 
> to keep routing table sizes down to something manageable, this was 
> thought not to be wise.

I don't see this as necessary. In fact in most cases traffic should/will 
follow the same path A->B. Its all about how its treated at each queueing