Setting Up A Mirror Port - Lucent Technologies Cajun P220 Operation Manual

Analyzing Network Performance Using RMON and Ethernet Statistics (Layer 2 & Layer 3)

Setting Up a Mirror Port

Configuring an RMON mirror port allows you to mirror traffic from a port or set of ports
to a specific mirror port, where you can attach a sniffer or RMON probe. The switch
supports a single mirror port and a single source port for each switch fabric port. For
example, 20-port Fast Ethernet cards have two fabric ports (one for ports 1 through 10,
one for ports 11 through 20). You can set up a single source port and a single mirror port
for each set of ports associated with a fabric port. You can also choose to mirror all traffic
from a particular fabric port to the mirror port, or set up multiple source ports to mirror
traffic to a single mirror port.
Packets addressed to the CPU, such as pings, are duplicated out of the mirror port.
Tagged packets that are sent into a source port with a VLAN ID to which the source port
is not bound, are not transmitted out the mirror port. VLAN tag information is not
propagated to the mirror port.
Note: To prevent unnecessary traffic flooding on a mirror port, put the mirror port
on the same VLAN as the source port.
To set up an RMON mirror port:
1. In the Port Mirroring section of the Web Agent window, click Sampling. The
Port Mirroring Information dialog box opens.
2. Use Table 17-2 to view your port mirroring information.
17-6 Cajun P550/P220 Switch Operation Guide