Nortel Networks NN46110-602 manual Filters and triggers, Capture filters, Triggers

108 Chapter 5 Packet capture

A global IP capture object captures packets beginning from the IP header; no Layer 2 header is saved in the capture file. Because both encrypted and decrypted packets are captured, global IP packet capture is useful in troubleshooting certain VPN issues.

Note: If capture objects for physical interfaces or tunnels are running at the same time as a global IP capture object, performance on the VPN Router is affected.

Filters and triggers

You can apply existing interface filters to a capture object as a capture filter or as a start or stop trigger. You configure capture filters, start triggers, and stop triggers independently.

Note: You cannot configure filters and triggers on ADSL/ATM interfaces.

Capture filters

To troubleshoot a specific type of problem and to limit the amount of data stored in the capture buffer, you can configure a predefined interface filter so that non-IP frames do not match any filter. For example, if you configure a capture object with a filter for a serial interface configured with PPP, no Link Control Protocol (LCP) traffic matches filter criteria on a capture object. You can configure the capture object to always capture non-IP frames or to always discard them.

To apply a filter to a capture object, you must first stop the capture object if it is running.

Triggers

By default, the system saves frames to the capture buffer as soon as a capture object starts. You can configure predefined or user-defined interface filters as triggers for capture objects. A trigger causes a capture object to start or stop automatically when they receive certain packets.

NN46110-602