Cisco Switched Port Analyzer (SPAN) Configuration Example

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Switched Port Analyzer (SPAN) Configuration

The Switched Port Analyzer (SPAN) feature (sometimes called port mirroring or port monitoring)
selects network traffic for analysis by a network analyzer. The network analyzer can be a Cisco
SwitchProbe, a Fibre Channel Analyzer.

Create a SPAN monitor session and specify the source and destination:

Configure SPAN Source:

Switch(config)#monitor session 1 source interface Fa0/1 ?
  ,     comma
  -     hyphen
  both  SPAN copies both egress and ingress traffic
  rx    SPAN copies only ingress traffic
  tx    SPAN copies only egress traffic
  <cr>
Switch(config)#monitor session 1 source interface Fa0/1
  • Ingress source (Rx): Traffic entering the switch through this source port is copied to the SPAN
    destination port.
  • Egress source (Tx): Traffic exiting the switch through this source port is copied to the SPAN
    destination port.


Configure SPAN Destination:

monitor session 1 destination interface Fa0/2


Full Configuration:

monitor session 1 source interface Fa0/1 both
monitor session 1 destination interface Fa0/2



SPAN Capture and verification


We will create an interface VLAN in the switch, that we will use to ping from the PC:

interface Vlan1
 ip address 172.31.120.254 255.255.255.0


We start a ping from the PC to the interface VLAN:

Check the capture in the Sniffer:


Delete a SPAN monitor session

we just need to add “no” keyword and specify the id of the monitor session to delete:

Switch(config)#no monitor session 1
Bilel A

Bilel A

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