Cisco Systems 3560 Small to Medium-Sized Network Using Catalyst 3560 Switches

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Catalyst 3560 Switch Software Configuration Guide
OL-8553-06
Chapter 1 Overview
Network Configuration Examples
Figure 1-2 Server Aggregation
Small to Medium-Sized Network Using Catalyst 3560 Switches
Figure 1-3 shows a configuration for a network of up to 500 employees. This network uses Catalyst 3560
Layer 3 switches 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.
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 one VLAN 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 switches are providing
inter-VLAN routing. VLAN access control lists (VLAN maps) on the switch 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.
For prestandard and IEEE 802.3af-compliant powered devices connected to Catalyst PoE switches, IEEE
802.1p/Q QoS gives voice traffic forwarding-priority over data traffic.
89376
Campus
core
Catalyst
6500 switches
Catalyst 3750
StackWise
switch stacks
Access-layer
Catalyst
switches
Server racks