Cisco MDS 9000 Series Troubleshooting Manual page 33

Chapter 1 Troubleshooting Overview
S e n d c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m .
To use a protocol analyzer, you must insert the analyzer in-line with the device under analysis, which
disrupts input and output (I/O) to and from the device. This problem is worse when the point of analysis
is on an Inter-Switch Link (ISL) link between two switches. In this case, the disruption may be
significant depending on what devices are downstream from the severed ISL link.
In Ethernet networks, this problem can be solved using the SPAN utility, which is provided with the
Cisco Catalyst Family of Ethernet switches. SPAN has also been implemented with the Cisco MDS 9000
Family of switches for use in Fibre Channel networks. SPAN lets you take a copy of all traffic and direct
it to another port within the switch. The process is non-disruptive to any connected devices and is
facilitated in hardware, which prevents any unnecessary CPU load. Using Fibre Channel SPAN, you can
connect a Fibre Channel analyzer, such as a Finisar analyzer, to an unused port on the switch and then
SPAN a copy of the traffic from a port under analysis to the analyzer in a non-disruptive fashion.
SPAN allows you to create up to 16 independent SPAN sessions within the switch. Each session can have
up to four unique sources and one destination port. In addition, you can apply a filter to capture only the
traffic received or the traffic transmitted. With Fibre Channel SPAN, you can even capture traffic from
a particular Virtual SAN (VSAN).
To start the SPAN utility use the CLI command
identifies a specific SPAN session. When you enter this command, the system displays a submenu, which
lets you configure the destination interface and the source VSAN or interfaces.
switch2# config terminal
switch2(config)# span session 1
<<Create a span session>>
switch2(config-span)# source interface fc1/8
<<specify the port to be spanned>>
switch2(config-span)# destination interface fc1/3
<<specify the span destination (SD) port>>
switch2(config-span)# end
switch2# show span session 1
Session 1 (active)
Destination is fc1/1
No session filters configured
Ingress (rx) sources are
Egress (tx) sources are
OL-5183-02, Cisco MDS SAN-OS Release 1.3
fc1/8,
fc1/8,
Using Cisco MDS 9000 Family Tools
span session session_num
Cisco MDS 9000 Family Troubleshooting Guide
, where session_num
1-17