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Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter1 Overview
Network Configuration Examples
Figure1-5 Linux Server Cluster
Small to Medium-Sized Network Using Catalyst 3750 Switches
Figure 1-6 shows a configuration for a network of up to 500employees. This network uses a
Catalyst 3750 Layer 3 switch stack with high-speed connections to two routers. For network reliability
and load balancing, this network has HSRP enabled on the routers and on the switches. This ensures
connectivity to the Internet, WAN, and mission-critical network resources if one of the routers or
switches fails. The switches are using routed uplinks for faster failover. They are also configured with
equal-cost routing for load sharing and redundancy. (A Layer2 switch stack can use cross-stack
EtherChannel for load sharing.)
The switches are connected to workstations, local servers, and IEEE 802.3af compliant and
noncompliant powered devices (such as Cisco IP Phones). The server farm includes a call-processing
server running Cisco CallManager software. Cisco CallManager controls call processing, routing, and
Cisco IP Phone features and configuration. The switches are interconnected through Gigabit interfaces.
This network uses VLANs to logically segment the network into well-defined broadcast groups and for
security management. Data and multimedia traffic are configured on the same VLAN. Voice traffic from
the Cisco IP Phones are configured on separate VVIDs. If data, multimedia, and voice traffic are
assigned to the same VLAN, only oneVLAN can be configured per wiring closet.
When an end station in one VLAN needs to communicate with an end station in another VLAN, a router
or Layer 3 switch routes the traffic to the destination VLAN. In this network, the switch stack is
providing inter-VLAN routing. VLAN access control lists (VLAN maps) on the stack provide
intra-VLAN security and prevent unauthorized users from accessing critical areas of the network.
In addition to inter-VLAN routing, the multilayer switches provide QoS mechanisms such as DSCP
priorities to prioritize the different types of network traffic and to deliver high-priority traffic. If
congestion occurs, QoS drops low-priority traffic to allow delivery of high-priority traffic.
86932
Campus
core
EtherChannel
across uplinks
Linux cluster
parallel-
processing
server farm
32-Gbps ring
Catalyst 3750
StackWise switch stack
Catalyst 3750
StackWise switch stack
Redundant SFP
module uplinks