SNEAK PREVIES

Cisco Catalyst 5000: A New Breed

by Art Wittmann

Think you've got a pretty good handle on all the nuances in switching hubs? Then you haven't seen Cisco's Catalyst 5000. Cisco has a scheme for delivering switched bandwidth throughout the network without ATM (or with it, if you choose), and the Catalyst 5000 is an important part of that scheme.

With the Catalyst 5000, Cisco is now redefining the basic requirements for the slotted chassis switching market. With the exception of Alantec, Cisco is also the first to deliver a switching architecture that really makes good on the promise of virtual LANs (VLANs) throughout a network.

The Catalyst 5000 has five slots, one of which is taken by a switching engine that Cisco claims can switch up to one million packets per second. The layer 2 and layer 3 switch can take two power supplies, and all add-in cards are hot swappable. The Catalyst's switching engine card also has two Fast Ethernet ports, which you can use for servers or as trunk lines to other Catalysts and routers.

Trunking is a term switch vendors will be talking about more and more. For switches, it refers to using a fast network port to carry traffic between switches from many VLANs. Cisco has also proposed a method of using the IEEE 802.10-packet tagging as a standard for moving VLAN traffic over shared media--like an FDDI backbone. While this method is still proprietary, it is a step in the right direction.

New Concepts From Cisco The Catalyst 5000 includes some new concepts and proprietary protocols to del iver VLAN support within the switch. Terms such as Encoded Address Recognition Logic (EARL), which is essentially the 5000's address lookup table, Cisco Discovery Protocol (CDP) and Inter-Switch Links (ISLs) are now part of the Cisco vocabulary.

Of these, CDP is perhaps the most interesting. It is used specifically for network management to allow discovery of devices that are neighbors to Cisco equipment. This allows a network management station (that knows the CDP MIB) to develop a physical view of the network even though you're using VLANs.

If you're an old hand at configuring Cisco routers, the interface on the 5000 will be familiar. There are a few notable additions, specifically dealing with setting up VLANs and other specific switching options.

I found that setting such things as port priorities and VLAN groups was fairly straightforward on the 5000--just a matter of assigning a VLAN number (much like a Cisco access control list number) and listing the ports that make up the VLAN. Creating trunks is simple too: Just designate a port and the VLANs that it should carry.

Presently, trunks only go to other Catalyst 5000s. Software supporting trunks and routing between VLANs is scheduled to be available for the 7000 family of routers around the end of the year.

Art Wittmann can be reached via the Internet at wittmann@engr.wisc.edu.

October 15, 1995