Brocade Network Advisor SAN User Manual v12.3.0 - Manual (Page 1242)

1190 Brocade Network Advisor SAN User Manual
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Flow Mirror
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Flow Mirror duplicates the specified frames in a user-defined flow, and sends them to a mirror port.
There are two types of mirrors:
• CPU Mirroring — Sends the duplicated frames to the local switch Control Processor Unit (CPU);
however, CPU Mirroring has a limit of 256 frames per second.
• Local Flow Mirroring (LFM) — Sends the duplicated frames to an unoccupied, loopback, or
mirror port on the same physical switch on which you defined the flow. LFM mirrored data can
then be analyzed through an external Analyzer/Frame sniffer connected to the port. LFM
requires that a loopback SFP be plugged in at the other end of the analyzer, or on the port
configured as a mirror port.
Note that if you select an unoccupied or loopback port, the Management application first
reconfigures the port as a mirror port, and then creates the flow. This enables you to mirror a
flow to a specific port, which is present on the same physical switch on which you defined the
flow.
You can create a Flow Mirror flow by creating a copy of the flow you want to examine. Flow Mirror
flows can be in an active state or an inactive state. If the mirror flow is “active”, mirroring starts
immediately; if the flow is “inactive”, the flow must be activated (refer to
“Activating flows” on
page 1136") for mirroring to start. Mirrored flows can be unidirectional or bidirectional.
A sample use case would be to mirror the traffic flow from a slow-draining F_Port to see what is
causing this condition.
“Diagnosing a slow-draining F_Port” on page 1199" provides an example of
this type of mirrored flow and the results for this use case.
Figure 513 provides a diagram of a mirrored flow with the ingress port mirroring the traffic flow to
the CPU. Flow Mirror can also mirror the egress port, but only one port (ingress or egress) can be
mirrored per flow. To mirror from one port in both flow directions (left to right and right to left), you
must use the Bidirectional option.
FIGURE 513 Mirror flow