Cabletron Systems STS16-20R Monitoring Port Traffic, 211, Active Monitoring, Passive Monitoring

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9. Monitoring Port Traffic

The SmartStack STS16-20D/STS16-20R allows you to configure a Switched Port Analyzer function for monitoring traffic on a port. An analyzer port is a port on which an external probe can observe traffic from any other port, that is a monitored port. The monitoring function is does not interfere in any way with the normal traffic flow in the switch.

The external probe (for example, a protocol analyzer) is not supplied with the switch.

You can monitor traffic going through a monitored port in two different ways, by using either:

•

•

active monitoring or

passive monitoring.

Active Monitoring

This mode copies traffic switched to and from the monitored port to the analyzer port. Since MAC frames never are switched between ports, they will not be seen on the analyzer port. To prevent spurious frames, the analyzer port must be a Token- Ring port on the same box as the monitored port. It is recommended that you put the analyzer port into a separate VLAN. The monitored port can be any type of port (Token-Ring, ATM, HSTR, and Fast Ethernet)

➽Note! The analyzer port works as a normal port. This means it can be in FDX/HDX mode, Station/Port 4 or 16 Mpbs. Moreover, you can use any external probe. The frames will be buffered normally, that is, if you try to monitor a FDX 16 MB line with a 4 MB HDX port, data loss can occur.

When the monitored port is in HDX mode, the frames sent to the analyzer port will be the frames received on the Token-Ring of the monitored ports (that is, a true copy apart from MAC frames). When monitoring a FDX port, it is the forwarding port that is responsible for the copy. As a consequence, packets may be seen on the analyzer port in a different order than on the monitored port. Moreover, since it is the monitored port itself that expands Source Route Explorer frames, the last ring and bridge number will be missing from explorer frames passing a BRF in the switch.

Passive Monitoring

This mode makes a physical connection from the monitored port to the analyzer port. Both the monitored and the analyzer port must be Token-Ring ports. You can choose to connect either the transmit or the receive wire from the monitored port to the analyzer port. That is, if the monitored port is in HDX mode, the analyzer port

Monitoring Port Traffic SmartStack STS16-20D/STS16-20R Token Ring Switches Installation and User Guide