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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 1 Overview
Network Configuration Examples
Figure 1-1
shows three configuration examples of using Catalyst switches to create the following:
•
Cost-effective wiring closet—A cost-effective way to connect many users to the wiring closet is to
connect a Catalyst switch cluster of up to nine Catalyst 3550 XL switches (or with a mix of
Catalyst 3550, Catalyst 2950, Catalyst 3500 XL, and Catalyst 2900 XL switches) through
GigaStack GBIC connections. To preserve switch connectivity if one switch in the stack fails,
connect the bottom switch to the top switch to create a GigaStack loopback, and enable cross-stack
UplinkFast on the cross-stack Gigabit uplinks.
You can have redundant uplink connections, using Gigabit GBIC modules, from the GigaStack
cluster to a Gigabit backbone switch such as the Catalyst 3550-12T or Catalyst 3550-12G switch.
You can also create backup paths by using Fast Ethernet, Gigabit, or EtherChannel links. If one of
the redundant connections fails, the other can serve as a backup path. You can configure the
Catalyst 3550-12T or Catalyst 3550-12G switch as a switch cluster manager to manage stack
members through a single IP address. The Catalyst 3550-12T or Catalyst 3550-12G switch can be
connected to a Gigabit server through a 1000BASE-T connection.
•
High-performance workgroup—For high-speed access to network resources, you can use
Catalyst 3550 switches in the access layer to provide Gigabit Ethernet to the desktop. To prevent
congestion, use QoS DSCP marking priorities on these switches. For high-speed IP forwarding at
the distribution layer, connect the Catalyst 3550 switches in the access layer to a Gigabit multilayer
switch (such as the Catalyst 3550 multilayer switch) in the backbone.
Each switch in this configuration provides users with a dedicated 1-Gbps connection to network
resources in the backbone. Compare this with the switches in a GigaStack configuration, where the
1-Gbps connection is shared among the switches in the stack. Using these Gigabit GBIC modules
also provides flexibility in media and distance options:
–
1000BASE-SX GBIC: fiber-optic connections of up to 1804 ft (550 m)
–
1000BASE-LX/LH GBIC: fiber-optic connections of up to 32,808 ft (10 km)
–
1000BASE-ZX GBIC: fiber-optic connections of up to 328,084 ft (100 km)
–
1000BASE-T GBIC: copper connections of up to 328 ft (100 m)
•
Redundant Gigabit backbone—Using HSRP, you can create backup paths between two
Catalyst 3550 multilayer switches to enhance network reliability and load balancing for different
VLANs and subnets. Using HSRP also provides faster network convergence if any network failure
occurs. You can connect the Catalyst switches, again in a star configuration, to two Catalyst 3550
multilayer backbone switches. If one of the backbone switches fails, the second backbone switch
preserves connectivity between the switches and network resources.
