Changes to stackable Cisco switch are all good

Box Score

Cisco's 3750 Series Gigabit Ethernet switch is fairly easy to set up with a new guide mode and wizards. And it's stackable for adding capacity.

Olivier Douliery

Years ago when networks began to expand rapidly, Cisco Systems Inc. came up with the idea of stacking up an inexpensive switch so that its service life could extend beyond immediate demands.

The Catalyst 3750 Series intelligent Ethernet switch we recently tested at the GCN Lab was more advanced than Cisco's earlier GigaStack. Although not too much has changed'a testament to the design'all the changes are positive.

The biggest difference: The Catalyst 3750 is optimized for Gigabit Ethernet.

Using our WebAvalanche server testing device from Spirent Communications of Sunnyvale, Calif. (formerly Caw Networks), we transferred 32G of traffic over the network ring without packet loss.

WebAvalanche simulates up to 1 million simultaneous connections, each from a different IP address. It measures the number of delayed or lost packets that require retransmission.

Like the earlier Cisco stackable switch, this one had a single management point, in our case an IP address. Any new console that we plugged in was automatically rerouted to the master console. An administrator could add capacity without the usual management headaches of new hardware.

An interesting aside: The master console doesn't have to be located at the bottom or top of the stack. It can be placed anywhere so long as its bidirectional cables form the master part of the ring.

The best thing, aside from good performance, is the graphical Web interface with wizards for setting up and managing the switch in a common Layer 3 configuration.

If you're somewhat in the dark about switch management, a special guide mode holds your hand for prioritizing traffic and setting up unicast or multicast routing. Expert network managers can go right to expert mode without the hand-holding.

Given so much redundant capacity in the ring, the switch could compensate for minor or major losses. We configured cross-stack EtherChannel and then began to send traffic from WebAvalanche. To duplicate a failure, we simply disconnected one of the cables. The switch immediately compensated without any packet loss.

We also shot various-size packets at the switch, including jumbo packets of 9,018 bytes each. Large packets have been known to overload systems with small backplanes or bog down store-and-forward units. But the Cisco 3750 didn't flinch. Latency increased, of course, but no packets were lost or dropped, and smaller packets continued to travel through the ring.

The Cisco 3750 performed as flawlessly as its Layer 3 predecessor, but on the management side the difference was night and day. No longer did we have to configure from an MS-DOS-style console. Once the master console was set, adding more hardware was as easy as plugging it in.

About the Author

John Breeden II is a freelance technology writer for GCN.

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