Troubleshooting Methodology

A key to troubleshooting QoS is to verify that the signaling messages are traversing the network as expected and are not dropped or blocked for any reason. Once this is verified, the next step is to verify that traffic control is being effectively and correctly invoked for controlled load and guaranteed service levels.

The practical first step is mapping out the network topology to identify all the network devices in the path from sender to receiver, and identify which devices participate in the RSVP signaling. It is important to identify these devices as they intercept RSVP messages that transit the shared segments. Tracert and Wdsbm are useful tools for determining network topology.

Tracking RSVP Messages from Source to Destination    Figure 9.10 describes the process of how to verify end-to-end signaling.

Figure 9.10 Verifying of End-to-end Signaling

Figure 9.11 describes the process of how to track the passage of RSVP messages.

Figure 9.11 Tracing RSVP Messages

Figure 9.12 describes how to verify the functionality of traffic control.

Figure 9.12 Verifying Traffic Control Functionality (802.1p)