Routers/Switches /

Gigabit switches for the midrange

Cisco's Catalyst 3550 and 2950 switches target midrange Layer 2/Layer 3 market.

By Edwin Mier, Betsy Yocom and Marc Frigo
Network World, 08/13/01

Gigabit switches are the engines of large enterprise LANs. But even midsize companies are feeling the LAN bandwidth pinch and retooling their networks on Gigabit infrastructures. This represents a new and rapidly growing market for Layer 2 and Layer 3 Gigabit switches.

This market includes Cisco's new Catalyst 3550-12T and 2950T-24 switches, which were introduced in May. We recently tested these switches and found they delivered at or near wire-speed Gigabit performance over Category 5 unshielded twisted pair copper cabling. They also support a full complement of features and a new management graphical user interface (GUI) - all for a competitive price.

Overall, we awarded the switches top ratings, although the management GUI has a few kinks.

Scorecard and NetResults
Detailed testing methods

Just inches from full wire speed

The Catalyst 3550-12T and the 2950T-24 are excellent performers, delivering wire-speed throughput with only a few exceptions. (See "How we did it") When we tested using minimum-sized 64-byte packets on the 3550-12T and full-duplex load on all 12 Gigabit ports, performance dipped slightly below 100%, to 92.32% of line speed in Layer 2 tests (media access control-layer switching) and 91.98% of line speed at Layer 3 (IP routing). Throughput tests performed with smaller packets apply the maximum workload on Layer 2/3 switches, and it's where throughput shortfalls typically occur. When we ran the 64-byte packet throughput tests on the 3550 using 10 (instead of 12) ports of full-duplex, Gigabit-rate traffic, we saw 100% line-rate throughput. This throughput performance more than adequately met the requirements of most midrange company LANs.

We measured latency, which was acceptable on both switches at less than a millisecond of delay on traffic passing through the 3550.

New midrange management

As Cisco has oriented these switches toward the midrange customer, it had to design a management that's less daunting than Ciscoworks 2000 and Cisco's command line interface (CLI). The result is the Cluster Management Suite (CMS), Cisco's take on the right mix of network management features and depth for this midrange environment.

CMS is a set of Java applets accessed via a Web browser (we used Internet Explorer Version 5.0), plus all the add-ons in the Java 2 Runtime Environment. The typical midrange customer would deploy at least one 3550 multilayer switch and some number of 2950 switches. The 3550, designated the "cluster command switch," becomes the network's focal point.

The administrator browses into the 3550 command switch to manage the whole cluster.

CMS comes close to hitting the mark as a simple, yet functionally adequate, management tool. Cisco could add some features, such as an alarm/event log. Currently the switches can issue SNMP traps out to a third-party SNMP manager, but there's no component for retaining or logging such events, alarms or traps.

Overall features and functionality, though, are just OK. Our so-so rating of management is based more on CMS operational issues. One major gripe is it takes a long time to load all the applets and for the interface to come up. And CMS remembers nothing from your last session. All the tweaking made to highlight specific interfaces or format graphs in your last management session is lost after logging off and browsing back into CMS or rebooting the switch. Because this version of CMS is new, it needs some fine-tuning before it will fly right.

There's also no real-time monitoring. None of the statistics update in real time; you have to manually refresh the screen for current data. And refreshing any statistic takes slightly longer than 5 seconds from a 3550, and more than 15 seconds from a 2950. Java brews slowly.

Statistics are displayed in one table for all switch interfaces at the same time. Refreshing updates for all the interfaces in the table concurrently, making it hard to focus on activity for a particular interface. You can graph activity on a particular interface, but the detail is not granular nor modifiable. The update frequency is also slow and occurs at erratic intervals.

Despite this, CMS' statistics are, for the most part, accurate. However, when the 3550's Gigabit ports are under heavy load, their traffic statistics often go awry.

The 3550 and 2950 perform well as Layer 2 switches out of the box. Configuration of the 3550 for routing is straightforward via CMS GUI. We've traditionally ranked a Cisco router configuration via CLI a 7 on a 10-point scale, where 10 is most difficult. A 3550 router configuration via CMS brings the technical difficulty down to between a 5 and 6.

Fully-featured and reliable

The 3550 and 2950 switches are designed to work together. The 3550-12T provides 10 fixed-configuration 1000Base-T, Gigabit-over-copper ports plus two gigabit interface card slots, which yielded two more 1000Base-T ports, for a total of 12. It can work alone, providing high-capacity Layer 2 or Layer 3 networking to server farms, or can provide for high-capacity interconnection of multiple Layer 2 Catalyst 2950T-24 switches (usually in wiring closets). The 2950T-24, a fixed-configuration switch, supports 24 10/100 ports and two Gigabit-over-copper "uplink" ports. The Gigabit ports on both switches operate over existing Cat 5 cabling, so do not require installation of optical fiber.

Typically, products lose points if they're not modular, but for midsize companies with modest technical staffs to install and maintain systems - the products' "fixed" nature is appropriate. Besides, up to 16 switches (3550-12T's and/or 2950T-24s) can be stacked in a cluster and managed via CMS.

Both switches support the full range of features typically found on Layer 2 switches - including Spanning Tree Protocol and virtual LAN support. The 3550 also supports full Layer 3 switching, including dynamic and static IP routing. Quality-of-service features are extensive, including 802.1p and q, strict-priority, weighted round robin and other IP-prioritization mechanisms. Reliability and redundancy features include support for Cisco's Hot Standby Router Protocol on the 3550-12T.

Conclusion

These switches pack a lot of power and are fairly easy to install and maintain. Competitively priced at $10,000, the Catalyst 3550-12T and its Catalyst 2950T-24 counterpart are ideal products for building Gigabit infrastructures in midrange companies.

SCORE: 4.15

COMPANY: Cisco, (408) 562-4000 COST: Cisco Catalyst 3550-12T costs $10,000 ($833 per port); Cisco Catalyst 2950T-24 costs $2,400 ($92 per port) PROS: At or near wire-speed performance; fully featured; easy to install; competitively priced. CONS: Some operational issues on the new CMS; no real-time monitoring.

3550-12T and 2950T-24
Performance 30%	5
Management 25%	3
Features 25%	4
Installation, Ease of use 10%	4
Configuration 10%	5
Total score	4.15

Individual category scores are based on a scale of 1 to 10. Percentages are the weight given each category in determining the total score.SCORING KEY: 5: Exceptional showing in this category. Couldn�t be better. May define the standard for excellence in this category. 4: A very good showing in this category. Although there may have been room for improvement, this product was much better than average. 3: An average showing in this category. The product was neither especially good nor exceptionally bad. 2: A below average showing in this category. The product lacked some features or had lower performance than other products, or than was expected from a product in this category. 1: Considerably sub-par, or lacking features being reviewed. A 1 is the lowest score that can be awarded.