Span And Rspan Concepts And Terminology; Span Sessions - Cisco Catalyst 3750 Software Configuration Manual

Chapter 21 Configuring SPAN and RSPAN
Figure 21-2
ports configured on Switch C.
Figure 21-2 Example of RSPAN Configuration
must support RSPAN VLAN
Switch A

SPAN and RSPAN Concepts and Terminology

This section describes concepts and terminology associated with SPAN and RSPAN configuration.

SPAN Sessions

SPAN sessions (local or remote) allow you to monitor traffic on one or more ports, or one or more
VLANs, and send the monitored traffic to one or more destination ports.
A local SPAN session is an association of a destination port with source ports or source VLANs, all on
a single network device. Local SPAN does not have separate source and destination sessions. Local
SPAN sessions gather a set of ingress and egress packets specified by the user and form them into a
stream of SPAN data, which is directed to the destination port.
RSPAN consists of at least one RSPAN source session, an RSPAN VLAN, and at least one RSPAN
destination session. You separately configure RSPAN source sessions and RSPAN destination sessions
on different network devices. To configure an RSPAN source session on a device, you associate a set of
source ports or source VLANs with an RSPAN VLAN. The output of this session is the stream of SPAN
78-15870-01
shows RSPAN source ports configured on Switch A and Switch B with RSPAN destination
destination ports
Switch C
Intermediate switches
RSPAN
source
session A
RSPAN
source ports
RSPAN
RSPAN
destination
session
RSPAN
VLAN
Switch B
RSPAN
source ports
Catalyst 3750 Metro Switch Software Configuration Guide
Understanding SPAN and RSPAN
RSPAN
source
session B
21-3