Brocade Fabric OS Command Reference Guide v6.1.0 (53-1000599-02, June 2008)

Fabric OS Command Reference 383
53-1000599-02
pathInfo
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When requested, statistics are reported below the routing information for each hop. These
statistics are presented for both the input and output ports, for both receive and transmit modes.
These statistics are divided into basic and extended statistics, which can be individually requested
in interactive mode. Statistics are not reported for the embedded port.
To collect these statistics, this command uses a special frame, the pathInfo frame, that is sent
hop-by-hop from the source switch to the destination switch. To prevent such a frame to loop
forever if an error occurs, a maximum number of hops for the frame to traverse is enforced. The
hop count includes all hops in the direct path from source to destination, and also all the hops in
the reverse path, if the tracing of the reverse path is requested. The default value for the maximum
hop count is 25.
Basic statistics Basic statistics report variables that give an indication of ISL congestion
along the path. They include the following:
B/s Bytes per second received or transmitted; reports for multiple time periods,
displayed in parentheses.
Txcrdz The length of time in milliseconds that the port has been prevented from
transmitting frames due to lack of buffer-to-buffer credit. It is an indication of
downstream congestion. This value reports for multiple time periods,
displayed in parentheses. Note that other commands, such as
portStatsShow, might express this value in units other than milliseconds.
Extended statistics
Extended statistics report variables of general interest. They include the
following:
F/s Frames per second received or transmitted; reports for multiple time periods,
displayed in parentheses.
Words Total number of 4-byte Fibre Channel words.
Frames Total number of frames.
Errors Total number of errors that might cause a frame not to be received correctly.
This includes CRC errors, bad EOF errors, frame truncated errors,
frame-too-short errors, and encoding errors inside a frame.
Reverse path In general, the path from port A on switch X to port B on switch Y might be
different from the path from port B to port A. The difference could be in the
links traversed between the same sequence of switches, or the reverse path
might even involve different switches. The -r option allows you to determine
both routing and statistics information for the reverse path, in addition to
those for the direct path.
Source route The source route option allows you to specify a sequence of switches, ports,
or areas that the pathInfo frame has to traverse to reach the destination.
Therefore, the path might be different from the one used by actual traffic.
The source route is expressed as a sequence of switches, a sequence of
output ports or areas, or a combination thereof. The next hop in the source
route is described by either the output port or area to be used to reach the
next hop, or the domain ID of the next hop.