Brocade Troubleshooting and Diagnostics Guide v6.1.0 (53-1000853-01, June 2008)

74 Fabric OS Troubleshooting and Diagnostics Guide
53-1000853-01
Port mirroring
9
The FC4-48 implements port pairing, meaning that two ports share the same area. Port pairing
uses a single area to map to two physical ports. A frame destined to the secondary port is
routed to the primary port. The primary port's filtering zone engine is used to redirect the frame
to the secondary port. Port mirroring uses the port filter zone engine to redirect the frames to
the mirror port. If two F_Ports share the same area, both ports cannot be part of a mirror
connection. One of the two ports can be part of the connection as long as the other port is
offline. Supported port configurations are shown in Table 14.
If IOD is enabled, adding or deleting a port mirror connection causes a frame drop. Port
mirroring reroutes a given connection to the mirror port, where the mirror traffic takes an extra
route to the mirror port. When the extra route is removed, the frames between the two ports
goes directly to the destination port. Since the frames at the mirror port could be queued at the
destination port behind those frames that went directly to the destination port, port mirroring
drops those frames from the mirror port when a connection is disabled. If IOD has been
disabled, port mirroring does not drop any frames but displays an IOD error.
• A port cannot be mirrored to multiple locations. If you define multiple mirror connections for
the same F_Port, all the connections must share the same mirror port.
• Local switches cannot be mirrored because FICON CUP frames to a local switch are treated as
well-known addresses or embedded frame traffic.
• Using firmware download to downgrade to previous Fabric OS releases that do not support port
mirroring requires that you remove all port mirroring connections.
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.
TABLE 14 Port combinations for port mirroring
Primary port Secondary port Supported
F_Port F_Port No
F_Port Offline Yes
Offline F_Port Yes
F_Port E_Port Yes
E_Port F_Port Yes
E_Port E_Port No