CHAPTER
15-1
Catalyst 3550 Multilayer Switch Software Configuration Guide
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15
Configuring SPAN
This chapter describes how to configure Switch Port Analyzer (SPAN) on your switch.
Note For complete syntax and usage information for the commands used in this chapter, refer to the
Catalyst 3550 Multilayer Switch Command Reference for this release.
This chapter consists of these sections:
Understanding SPAN, page 15-1
Configuring SPAN, page 15-6
Displaying SPAN Status, page 15-13

Understanding SPAN

You can analyze network traffic passing through ports or VLANs by using SPAN to send a copy of the
traffic to another port on the switch that has been connected to a SwitchProbe device or other Remote
Monitoring (RMON) probe. SPAN mirrors received or sent (or both) traffic on a source port, or receive d
traffic on one or more source ports or source VLANs, to a destination port for analysis.
For example, in Figure 15-1, all traffic on Gigabit Ethernet port 5 (the source port) is mi rrored to Gigabit
Ethernet port 10 (the destination port). A network analyzer on port 10 receive s all networ k tr affic fr om
port 5 without being physically attached to port 5.