Internetworking bandwidth

Bandwidth Management

To optimize backbone network operations, routers offer several performance tuning features. Examples include priority queuing, routing protocol metrics, and local session termination.

You can adjust the output queue length on priority queues. If a priority queue overflows, excess packets are discarded and quench messages that halt packet flow are sent, if appropriate, for that protocol. You can also adjust routing metrics to increase control over the paths that the traffic takes through the Internetwork.

Local session termination allows routers to act as proxies for remote systems that represent session endpoints. (A proxy is a device that acts on behalf of another device.) Figure 2-12 illustrates an example of local session termination in an IBM environment.

Figure 2-12: Local session termination over multiprotocol backbone.

In Figure 2-12, the routers locally terminate Logical Link Control type 2 (LLC2) data-link control sessions. Instead of end-to-end sessions, during which all session control information is passed over the multiprotocol backbone, the routers take responsibility for acknowledging packets that come from hosts on directly attached LANs. Local acknowledgment saves WAN bandwidth (and, therefore, WAN utilization costs), solves session timeout problems, and provides faster response to users.