User's Manual

29-3
Catalyst 3750 Switch Software Configuration Guide
OL-8550-09
Chapter 29 Configuring SPAN and RSPAN
Understanding SPAN and RSPAN
Figure 29-2 is an example of a local SPAN in a switch stack, where the source and destination ports
reside on different stack members.
Figure 29-2 Example of Local SPAN Configuration on a Switch Stack
Remote SPAN
RSPAN supports source ports, source VLANs, and destination ports on different switches (or different
switch stacks), enabling remote monitoring of multiple switches across your network. Figure 29-3 shows
source ports on Switch A and Switch B. The traffic for each RSPAN session is carried over a
user-specified RSPAN VLAN that is dedicated for that RSPAN session in all participating switches. The
RSPAN traffic from the source ports or VLANs is copied into the RSPAN VLAN and forwarded over
trunk ports carrying the RSPAN VLAN to a destination session monitoring the RSPAN VLAN. Each
RSPAN source switch must have either ports or VLANs as RSPAN sources. The destination is always a
physical port, as shown on Switch C in the figure.
Switch 1
1/0/4
2/0/15
Switch 2
Network
analyzer
Switch 3
Catalyst 3750 switch stack
86703
Stackwise
port
connections
Port 4 on switch 1 in the stack
mirrored on port 15 on switch 2
Port 4 on switch 1 in the stack
mirrored on port 15 on switch 2
Port 4 on switch 1 in the stack
mirrored on port 15 on switch 2