Users Guide

Table Of Contents
Monitoring Switch Traffic 649
Configuring RSPAN
RSPAN supports the transport of mirrored packets across the network to a
remote switch. Ports may be configured as source ports, intermediate ports, or
destination ports.
RSPAN Source Switch
This example mirrors interface gi1/0/3 to VLAN 723. VLAN 723 is the
selected transit VLAN. Administrators should reserve a VLAN as the RSPAN
VLAN when designing their network. The source switch requires a reflector
port to carry packets to the transit switch. The reflector port must be
configured as trunk port. Untagged packets on the source port are transmitted
on the RSPAN VLAN tagged with the RSPAN VLAN. Tagged packets on the
source port are transmitted over the RPSAN VLAN double-tagged with the
outer tag containing the RSPAN VLAN.
Note that neither the source port nor the destination (probe) port are
members of the RSPAN VLAN. Both ports are configured as access
(untagged) ports.
The last line in this configuration enables the monitor session. It is
recommended that configuration proceed with the destination switch first,
followed by the intermediate switches, and then by the source switch.
1
Configure RSPAN on VLAN 723:
console#configure
console(config)#vlan 723
console(config-vlan723)#remote-span
console(config-vlan723)#exit
2
Configure interface te1/0/1 as the reflector port in trunk mode:
console(config)#interface te1/0/1
console(config-if-Te1/0/1)#switchport mode trunk
console(config-if-Te1/0/1)#switchport trunk allowed vlan 723
console(config-if-Te1/0/1)#exit
3
Configure a mirroring session with a source port gi1/0/3, the destination
VLAN 723, and reflector port te1/0/1:
console(config)#monitor session 1 source interface gi1/0/3
console(config)#monitor session 1 destination remote vlan 723
reflector-port te1/0/1
4
Enable the monitor session:
console(config)#monitor session 1 mode