Port Mirroring Considerations; Creating, Deleting, And Displaying Port Mirroring - HP A7533A - Brocade 4Gb SAN Switch Base Administrator's Manual

Port mirroring considerations

Before creating port mirror connections, consider the following limitations:
• A mirror port can be any port on the same switch as the source identifier port.
• Only one domain can be mirrored per chip; after a domain is defined, only mirror ports on the defined
domain can be used.
For example, in a three-domain fabric containing switches 4100A, 4100B, and 4100C, a mirror
connection that is created between 4100A and 4100B only allows 4100A to add mirror connections for
those ports on 4100B. To mirror traffic between 4100A and 4100C, add a mirror connection on
4100C. The first connection defines the restriction on the domain, which can be either the local domain
or a remote domain.
• A switch that is capable of port mirroring can support a maximum of four mirror connections.
Each Field Description Block (FDB) defines an offset to search. Each offset can have up to four values
that can be defined for a filter. If any of the four values match, the filter will match.
• Mirror port bandwidth limits mirror connections.
The bandwidth of the mirror port is unidirectional. The host (SID) talks to multiple storage devices (DIDs)
and does not send full line rate to a single target. A mirror port configured at 2Gb can only support up
to 2Gb of traffic. A normal 2G F_Port is bidirectional and can support up to 4Gb of traffic (two to
transmit and two to receive). If the mirror port bandwidth is exceeded, the receiver port is not returned
any credits and the devices in the mirror connection see degraded performance.
• Deleting a port mirroring connection with In Order Deliver (IOD) enabled causes frame drop between
two endpoints.
• Using the firmware download procedure to downgrade to previous Fabric OS releases that do not
support port mirroring requires that you remove all the port mirroring connections. If you downgrade to
a previous versions of Fabric OS, you cannot proceed until the mirroring connections are removed.

Creating, deleting, and displaying port mirroring

The method for adding a port mirror connection between two local switch ports and between a local
switch port and a remote switch port is the same. First you must configure a port to be a mirror port before
you can perform a portMirror --add, or portMirror --delete.
To configure a port to be a mirror port:
• Type portcfg mirrorport slot/port
NOTE: The enable command enables the port as mirror port. The disable command disables the
mirror port configuration.
To add a port mirror connection:
1. Log in to the switch as admin.
2. Type portMirror --add slotnumber/portnumber SourceID DestID
NOTE: The lower 8 bits of the address is ignored. For example, the ALPA for loop devices.
The configuration database keeps information about the number of port mirror connections configured on
a switch, the number of chunks of port mirroring data that are stored, and the chunk number. When
removing a mirror connection, always use this method to ensure that the data is cleared. Deleting a
connection removes the information from the database.
324 Troubleshooting
enable.
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