QOS or more bandwidth

Pete Kruckenberg pete at kruckenberg.com
Tue May 29 20:07:25 UTC 2001

TE isn't just for congestion avoidance/mitigation. It's also
for choosing the best path, based on the costs and
characteristics of the traffic, as well as the load on the

So delay-intolerant (voice, video) traffic gets preference
on the lowest latency path, and pushes delay-tolerant flows
to alternate higher-latency (possibly longer) unused paths.
MPLS constraint-based routing allows this, as does ATM. PBR
w/ IP routing would be extremely complicated to do this.

Same rules can be applied to homogeneous traffic, where I
can manage at a finer granularity than
per-desination-CIDR-block. I can move traffic around my
network internally as well as to peers, to get full
utilization out of my network without introducing

This presumes a network with multiple paths to a given
destination, with approximately equal performance and cost.


On Tue, 29 May 2001, Ukyo Kuonji wrote:
> How is TE part of QoS?  Maybe we are talking a different
> type of TE.  To me, TE is the part that the traffic
> takes, not really what queue it sits in to transmit.
> I could see a arguement for QoS being part of TE, but...
> (Assuming that you TE your netword so there is no
> conjestion.)
> --- Original Message ---
> Everything that you said is correct.  However, you missed one
> important part of QoS, which is TE.  TE is about avoiding congestion
> in the first place by more efficiently using all of the bandwidth
> you already have in the network.  To that extent, it is a substitute
> for adding more pipe.

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