Abstract

The LAN switch market is chock full of products that offer switched Ethernet or Fast Ethernet connections. But for some network managers, there’s a legitimate need for a device that offers a middle-ground where you can achieve better performance than switched Ethernet without the associated costs of jumping to switched 100 Mbit/s Fast Ethernet. 

Lucent Technologies now offers such functionality with its Cajun P110 switch family. The vendor commissioned The Tolly Group to evaluate the effectiveness of the Cajun P110 switches innovative Fast Ethernet Group Switching approach versus switched Ethernet and Fast Ethernet switching alternatives. Group Switching allows groups of shared-bandwidth ports to be switched between one another; switch ports share the aggregate 100 Mbit/s bandwidth, or ports can use the maximum available bandwidth. 

In addition to the Group Switching feature, the Cajun P110 switches addresses a major limitation of stackable switches. Until now, stackables have been unable to provide non-blocking access among members of the same stack, since they often use oversubscribed Fast Ethernet links connected to a switch’s user ports. Instead, Lucent Technologies commissioned The Tolly Group to evaluate its Exoplane, a 4 Gbit/s external back- plane that allows traffic to flow freely be- tween as many as four Cajun P110 switches in a stack. 

Lucent Technologies; also layered in congestion control facilities as another means to address link oversubscription, plus inte- grated its own Switch monitoring (SMON) network management interface for the Ca- jun P110 switching system. 

Testing demonstrated that Lucent Technologies’ Cajun P115G, a 25-port Fast Ethernet switch that uses Group Switching, delivers 28% more throughput of IP traffic than a 10 Mbit/s Ethernet switch, and just 21% less throughput than a 100 Mbit/s Fast Ethernet switch. The Cajun P115G supports three shared segments consisting of eight ports each and one uplink port. 

Moreover, Lucent Technologies’ congestion control, which is marketed under the name Active Congestion Control, proved to be effective, eliminatng frame loss entirely, and SMON demonstrated that it offers accurate network management statistics for the Cajun P110 switches. Testing was performed in May 1998.