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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-21521-01
Chapter 1 Overview Network Configuration Examples
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 Catalyst 3750-X-only
switch stack or Catalyst 3560-X switches are providing inter-VLAN routing. VLAN access control lists
(VLAN maps) on the switch stack or 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.
Catalyst PoE switch ports automatically detect any Cisco pre-standard and IEEE 802.3af-compliant
powered devices that are connected. Each PoE switch port provides 15.4 W of power per port. The
powered device, such as a Cisco IP Phone, can receive redundant power when it is also connected to an
AC power source. Powered devices not connected to Catalyst PoE switches must be connected to AC
power sources to receive power.
Cisco CallManager controls call processing, routing, and Cisco IP Phone features and configuration.
Users with workstations running Cisco SoftPhone software can place, receive, and control calls from
their PCs. Using Cisco IP Phones, Cisco CallManager software, and Cisco SoftPhone software integrates
telephony and IP networks, and the IP network supports both voice and data.
With the multilayer switches providing inter-VLAN routing and other network services, the routers
focus on firewall services, Network Address Translation (NAT) services, voice-over-IP (VoIP) gateway
services, and WAN and Internet access.
Figure 1-7 Catalyst 3750-X-Only Switch Stack in a Collapsed Backbone Configuration
Gigabit
servers
200859
Cisco 2600 or
3700 routers
StackWise Plus
switch stack
Internet
Cisco IP
phones Workstations
running
Cisco SoftPhone
software
Aironet wireless
access points
IP IP