Configure Frame Relay for Voice over IP

Configure Custom Queuing

Some QoS features, such as IP RTP reserve and custom queuing, are based on the transport protocol and the associated port number. Real-time voice traffic is carried on UDP ports ranging from 16384 to 16624. This number is derived from the following formula:

16384 = 4(number of voice ports in the Cisco 3600 series router)

Custom Queuing and other methods for identifying high priority streams should be configured for these port ranges. For more information about custom queuing, refer to the “Performing Basic System Management” chapter in the Configuration Fundamentals Configuration Guide.

Configure Weighted Fair Queuing

Weighted fair queuing ensures that queues do not starve for bandwidth and that traffic gets predictable service. Low-volume traffic streams receive preferential service; high-volume traffic streams share the remaining capacity, obtaining equal or proportional bandwidth.

In general, weighted fair queuing is used in conjunction with Multilink PPP with interleaving and RSVP or IP Precedence to ensure that voice packet delivery. Use weighted fair queuing with Multilink PPP to define how data will be managed; use RSVP or IP Precedence to give priority to voice packets. For more information about weighted fair queuing, refer to the “Performing Basic System Management” chapter in the Configuration Fundamentals Configuration Guide.

Configure Frame Relay for Voice over IP

You need to take certain factors into consideration when configuring Voice over IP for it to run smoothly over Frame Relay. A public Frame Relay cloud provides no guarantees for QoS. For real-time traffic to be transmitted in a timely manner, the data rate must not exceed the committed information rate (CIR) or there is the possibility that packets will be dropped. In addition, Frame Relay traffic shaping and RSVP are mutually exclusive. This is particularly important to remember if multiple DLCIs are carried on a single interface.

For Frame Relay links with slow output rates (less than or equal to 64 kbps) where data and voice are being transmitted over the same PVC, we recommend the following solutions:

•Separate DLCIs for voice and data—By providing a separate subinterface for voice and data, you can use the appropriate QoS tool per line. For example, each DLCI would use 32 kbps of a 64 kbps line.

—Apply adaptive traffic shaping to both DLCIs.

—Use RSVP or IP Precedence to prioritize voice traffic.

—Use compressed RTP to minimize voice packet size.

—Use weighted fair queuing to manage voice traffic.

•Lower MTU size—Voice packets are generally small. By lowering the MTU size (for example, to 300 bytes), large data packets can be broken up into smaller data packets that can more easily be interwoven with voice packets.

Note Some applications do not support a smaller MTU size. If you decide to lower MTU size, use the ip mtu command; this command affects only IP traffic.

VC-22Voice, Video, and Home Applications Configuration Guide

3600 specifications

Cisco Systems 3600 is a high-performance modular router series designed for small to medium-sized enterprises and branch offices. Launched in the late 1990s, it has been widely recognized for its flexibility, scalability, and reliability. The series is part of Cisco's extensive networking portfolio and has played a vital role in delivering various services and applications while enhancing operational efficiency.

One of the main features of the Cisco 3600 series is its modular architecture, allowing organizations to customize the router according to their specific needs. The system supports various interface modules that can accommodate different types of connections, including serial, Ethernet, and DSL, which helps in building versatile network solutions. The modularity not only increases the router’s lifespan by enabling upgrades as technology changes but also supports future expansion as the organization grows.

The Cisco 3600 series routers utilize advanced routing protocols, such as RIP, OSPF, EIGRP, BGP, and IS-IS, to ensure efficient data transmission and optimal network performance. This capability allows the routers to adapt to varying traffic demands and complexities, thereby optimizing bandwidth utilization and reducing latency in communications. With extensive memory options, including Flash and DRAM, the 3600 series can handle robust data processing and support intricate routing environments.

Security is another critical feature of the Cisco 3600 series. It includes support for VPNs, firewalls, and other security protocols, providing a secure environment for data transfer. The implementation of features like Access Control Lists (ACLs) and Intrusion Detection Systems (IDS) enhances the overall security posture, making it suitable for organizations looking to protect their sensitive information.

In terms of scalability, Cisco 3600 routers can easily accommodate increased workloads and network growth. This is done through the provision of additional modules and cards to increase capacity and performance. The series can also support multiple WAN connections, enabling seamless integration with various telecommunication services.

Additionally, the Cisco 3600 series is designed for ease of management. Utilizing Cisco's IOS software, network administrators can manage and configure the routers efficiently, thanks to a user-friendly interface and extensive command capabilities. This makes troubleshooting simpler and ensures network availability remains high.

In conclusion, Cisco Systems 3600 series routers combine robust performance, security features, and scalability, making them an invaluable asset for businesses looking to maintain a reliable and efficient networking solution.