Specifications

Chapter 6 Configuring VoIP
Configure IP Networks for Real-Time Voice Traffic
6-4
Catalyst 4224 Access Gateway Switch Software Configuration Guide
OL-2031-02
weighted fair queuing), and IP precedence. To configure your IP network for
real-time voice traffic, you need to consider the entire scope of your network and
then select the appropriate QoS tool or tools.
To improve voice network performance, QoS must be configured throughout your
network, not just on your Catalyst 4224 running VoIP. Not all QoS techniques are
appropriate for all network routers. Edge routers and backbone routers in your
network do not necessarily perform the same operations, and the QoS tasks they
perform might differ as well. To configure your IP network for real-time voice
traffic, you need to consider the functions of both edge and backbone routers in
your network and then select the appropriate QoS tool or tools.
In general, edge routers perform the following QoS functions:
• Packet classification
• Admission control
• Bandwidth management
• Queuing
In general, backbone routers perform the following QoS functions:
• High-speed switching and transport
• Congestion management
• Queue management
Scalable QoS solutions require cooperative edge and backbone functions.
Although not mandatory, some QoS tools can be valuable in fine-tuning your
network to support real-time voice traffic. To configure your IP network for QoS,
perform one or more of the following tasks:
• Configure RSVP for Voice, page 6-5
• Configure Multilink Point-to-Point Protocol with Interleaving, page 6-7
• Configure Real-Time Transport Protocol Header Compression, page 6-9
• Configure Custom Queuing, page 6-11
• Configure Weighted Fair Queuing, page 6-12
Each of these tasks is discussed in the following sections.