Local Span; Remote Span - Cisco Catalyst 3750 Software Configuration Manual

Metro switch

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Table of Contents

Understanding SPAN and RSPAN

This section includes these topics:

Local SPAN

Local SPAN supports a SPAN session entirely within one switch; all source ports or source VLANs and

destination ports reside in the same switch. Local SPAN copies traffic from one or more source ports in

any VLAN or from one or more VLANs to a destination port for analysis. For example, in

all traffic on port 5 (the source port) is mirrored to port 10 (the destination port). A network analyzer on

port 10 receives all network traffic from port 5 without being physically attached to port 5.

Figure 21-1 Example of Local SPAN Configuration on a Switch

RSPAN supports source ports, source VLANs, and destination ports on different switches, enabling

remote monitoring of multiple switches across your network. 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.

Catalyst 3750 Metro Switch Software Configuration Guide

Local SPAN, page 21-2

Remote SPAN, page 21-2

SPAN and RSPAN Concepts and Terminology, page 21-3

SPAN and RSPAN Interaction with Other Features, page 21-8

1 2 3 4 5 6 7 8 9 10 11 12

Network analyzer

Port 5 traffic mirrored

Configuring SPAN and RSPAN