Large Network Using Only Catalyst 3550 Switches - Cisco Catalyst 3550 series Software Configuration Manual

Chapter 1 Overview
Network Configuration Examples

Large Network Using Only Catalyst 3550 Switches

Switches in the wiring closet have traditionally been Layer 2-only devices, but as network traffic profiles
evolve, switches in the wiring closet are increasingly employing multilayer services such as multicast
management and traffic classification. Figure 1-3 shows a configuration for a network exclusively using
Catalyst 3550 multilayer switches in the wiring closets and a Catalyst 6000 switch in the backbone to
aggregate up to ten wiring closets.
In the wiring closet, each Catalyst 3550 switch has IGMP snooping enabled to efficiently forward
multimedia and multicast traffic. QoS ACLs that either drop or mark nonconforming traffic based on
bandwidth limits are also configured on each switch. VLAN maps provide intra-VLAN security and
prevent unauthorized users from accessing critical pieces of the network. QoS features can limit
bandwidth on a per-port or per-user basis. The switch ports are configured as either trusted or untrusted.
You can configure a trusted port to trust the CoS value, the DSCP value, or the IP precedence. If you
configure the port as untrusted, you can use an ACL to mark the frame in accordance with the network
policy.
Within each wiring closet is a Catalyst 3550 multilayer switch for inter-VLAN routing. These switches
provide proxy ARP services to determine IP and MAC address mapping, thereby removing this task from
the routers and lessening this type of traffic on the WAN links. These switches also have redundant
uplink connections to the backbone switches, with each uplink port configured as a trusted routed uplink
to provide faster convergence in case of an uplink failure.
The routers and Catalyst 6000 multilayer backbone switches have HSRP enabled for load balancing and
redundant connectivity to guarantee mission-critical traffic.
The Catalyst 6000 switch provides the workgroups with Gigabit access to core resources. The server
farm includes a call-processing server running Cisco CallManager software. Cisco CallManager controls
call processing, routing, and IP phone features and configuration.
Catalyst 3550 Multilayer Switch Software Configuration Guide
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