Capture Filters; Permitted Capture Filters - Cisco AP776A - Nexus Converged Network Switch 5020 Configuration Manual

Chapter 58 Troubleshooting Your Fabric
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Capture Filters

You can limit what frames are captured by using the capture filters feature in a remote capture. This
feature limits the frames that are captured and sent from the remote switch to the host. For example, you
can capture only class F frames. Capture filters are useful in restricting the amount of bandwidth
consumed by the remote capture.
Unlike display filters, capture filters restrict a capture to the specified frames. No other frames are visible
until you specify a completely new capture.
The syntax for capture filters is different from the syntax for display filters. Capture filters use the
Berkeley Packet Filter (BPF) library that is used in conjunction with the libpcap freeware. The list of all
valid Fibre Channel capture filter fields are provided later in this section.
Procedures to configure capture filters are already documented in the Ethereal web site
(http://www.wireshark.org). Some examples of how you can use this feature follows:
•
•
•
•
•
This feature is part of libpcap and you can obtain more information from http://www.tcpdump.org.
Note

Permitted Capture Filters

This section lists the permitted capture filters.
o vsan
o src_port_idx
o dst_port_idx
o sof
o r_ctl
o d_id
o s_id
o type
o seq_id
o seq_cnt
o ox_id
OL-18084-01, Cisco MDS NX-OS Release 4.x
To capture frames only on a specified VSAN, use this expression:
vsan = 1
To capture only class F frames, use this expression:
class_f
To capture only class Fibre Channel ELS frames, use this expression:
els
To capture only name server frames, use this expression:
dns
To capture only SCSI command frames, use this expression:
fcp_cmd
Switch (Remote) 0xfffc04
Switch (Adjacent) 0xfffc01
Switch (Local) 0xfffc79
Cisco MDS 9000 Family CLI Configuration Guide
Cisco Fabric Analyzer
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