KB.15.15

Configure a destination switch in a remote mirroring session

Enter the mirror endpoint ip command on the remote switch to configure the switch as a

remote endpoint for a mirroring session with a different source switch.

Configure a mirroring session on the source switch

To configure local mirroring, only a session number and exit port number are required.

If the exit port for a mirroring destination is on a remote switch instead of the local (source) switch,

you must enter the source IP address, destination IP address, and UDP port number for the remote

mirroring session. You may also wish to enable frame truncation to allow oversize frames to be

truncated rather than dropped.

Frames that exceed the maximum size (MTU) are either dropped or truncated, according to the

setting of the [truncation] parameter in the mirror command. Frames that are near the MTU

size may become oversize when the 54-byte remote mirroring tunnel header is added for transport

between source switch and destination switch. (The addition of the header is a frequent cause for

frames becoming oversize, but note that all oversize frames, whatever the cause of their excess

size, are dropped or truncated.) If a frame is truncated, bytes are removed from the end of the

frame. This may cause the checksum in the original frame header to fail. Some protocol analyzers

may flag such a checksum mismatch as an alert.

NOTE: Note that if you enable jumbo frames to allow large frames to be transmitted, you must

enable jumbo frames on all switches in the path between source and destination switches.

Configure a source switch in a remote mirroring session

Enter the mirror remote ip command on the source switch to configure a remote destination

switch for a mirroring session on the source switch. The source IP address, UDP port number, and

destination IP address that you enter must be the same values that you entered with the mirror

endpoint ip command.

CAUTION: After you configure a mirroring session with traffic-selection criteria and a destination,

the switch immediately starts to mirror traffic to the destination device connected to each exit port.

In a remote mirroring session that uses IPv4 encapsulation, if the remote (endpoint) switch is not

already configured as the destination for the session, its performance may be adversely affected

by the stream of mirrored traffic. For this reason, HP Switch strongly recommends that you configure

the endpoint switch in a remote mirroring session, as described in “Configure a mirroring destination

on a remote switch” (page 349), before using the mirror remote ip command in this section

to configure the mirroring source for the same session.

Configure the monitored traffic in a mirror session

This step configures one or more interfaces on a source switch with traffic-selection criteria to select

the traffic to be mirrored in a local or remote session configured in section “Configure a mirroring

session on the source switch” (page 350).

350 Monitoring and Analyzing Switch Operation