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Today's focus: Tolly tests QoS on Cisco, Extreme switches
By Jeff Caruso
Kevin Tolly recently let me know about another LAN-related test his firm
performed. This one, commissioned by Avaya, pits
Extreme Networks switches against Cisco switches.
The approach, Tolly says, was unconventional. Countless other tests of
various equipment have measured the effectiveness of
QoS controls on traffic that experiences congestion upon leaving the
backplane and going out to the edge. That is, too much
traffic is coming from the backplane and trying to squeeze onto one output
port.
In this case, however, the Tolly Group measured the effectiveness of
dealing with traffic when there is congestion
going to the backplane. The example Tolly gave was that 40G bit/sec of
traffic could be going to a backplane that has only
20G bit/sec of capacity. Tolly believes this is a first for QoS testing.
Tolly tested Extreme's BlackDiamond 8810 and 10808 and Cisco's Catalyst
4507 and 6509. The aim was to determine how these
switches might do under a heavy load of voice, video and data.
How would each device fare?
Tolly says:
"This test shows that Extreme's QoS solution works effectively in either
'egress' or 'ingress' congestion situations. It also
shows that while Cisco can perform 'egress' congestion control, its QoS
simply does not work in 'ingress' congestion scenarios.
Thus, in a converged 'triple play' enterprise, high-priority Cisco's
core/edge solutions cannot provide voice and video
streams the 'protection' they need from being overwhelmed by low-priority
traffic."
When the background traffic load was turned up, the Extreme switches still
managed to get 100% of voice calls through, while
the Cisco switches "were unable to complete 100% of the calls, dropped
high-priority data traffic and failed to deliver all of
the IP video streams," according to the report.For the full report, go to:
