Small To Medium-Sized Network Using Catalyst 3560 Switches - Cisco WS-C3560-48PS-S Software Configuration Manual

Chapter 1 Overview
Table 1-3 Providing Network Services (continued)
Network Demands
An evolving demand for IP telephony
A growing demand for using existing
infrastructure to transport data and
voice from a home or office to the
Internet or an intranet at higher
speeds

Small to Medium-Sized Network Using Catalyst 3560 Switches

Figure 1-1
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 in case 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
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 appropriate destination VLAN. In this network, the switches
are providing inter-VLAN routing. VLAN access control lists (VLAN maps) on the switches provide
intra-VLAN security and prevent unauthorized users from accessing critical pieces 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 in a
predictable manner. If congestion occurs, QoS drops low-priority traffic to allow delivery of
high-priority traffic.
For pre-standard and IEEE 802.3af-compliant powered devices connected to Catalyst Power over
Ethernet (PoE) switches, 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 an 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.
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Suggested Design Methods
Use QoS to prioritize applications such as IP telephony during congestion and to
•
help control both delay and jitter within the network.
• Use switches that support at least two queues per port to prioritize voice and data
traffic as either high- or low-priority, based on 802.1P/Q. The Catalyst 3560
switch supports at least four queues per port.
• Use voice VLAN IDs (VVIDs) to provide separate VLANs for voice traffic.
Use the Catalyst Long-Reach Ethernet (LRE) switches to provide up to 15 Mb of IP
connectivity over existing infrastructure, such as existing telephone lines.
LRE is the technology used in the Catalyst 2900 LRE XL and Catalyst 2950
Note
LRE switches. Refer to the documentation sets specific to these switches for
LRE information.
shows a configuration for a network of up to 500 employees. This network uses Catalyst 3560
Network Configuration Examples
Catalyst 3560 Switch Software Configuration Guide
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