Configure Port Mirroring

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Port mirroring monitors the packets of a particular port on another port. The following example shows how to mirror all incoming packets on port 25 to port 26.

See Basic SEFOS Topology for the topology for this task. Type the following commands on the SEFOS-1 switch.

Connect to SEFOS.
See Connect to SEFOS.

Configure the IP address of the switch as 12.0.0.1.

SEFOS-1# configure terminal
SEFOS-1(config)# interface vlan 1
SEFOS-1(config-if)# shutdown
SEFOS-1(config-if)# ip address 12.0.0.1  255.0.0.0
SEFOS-1(config-if)# no shutdown
SEFOS-1(config-if)# end

View the ping between the host and the switch.

SEFOS-1# ping 12.0.0.100
 
Reply Received From :12.0.0.100, TimeTaken : 60 msecs
Reply Received From :12.0.0.100, TimeTaken : 100 msecs
Reply Received From :12.0.0.100, TimeTaken : 90 msecs
 
--- 12.0.0.100 Ping Statistics ---
3 Packets Transmitted, 3 Packets Received, 0% Packets Loss

The ping reply from host A to the switch is not captured at port 26, which is connected to the packet capturing device prior to the port-mirroring configuration.

Type the following commands on the SEFOS-1 switch to enable mirroring for incoming packets at port 25 to port 26:

Enter Global Configuration mode.
```
SEFOS-1# configure terminal
```

Configure the destination interface for mirroring as port 26.

SEFOS-1(config)# monitor session destination interface xl-ethernet 0/26

Configure the source interface for mirroring as port 25 and apply mirroring for incoming packets.
```
SEFOS-1(config)# monitor session source interface xl-ethernet 0/25 rx
```

Exit Global Configuration mode.
```
SEFOS-1(config-if)# end
```

View the configuration details.

SEFOS-1# show port-monitoring
 
Port Monitoring  is enabled
Monitor Port : X10/26
 
Port        Ingress-Monitoring    Egress-Monitoring
----        ------------------    -----------------
X10/25 Enabled               Disabled
...

Ping 12.0.0.100 and verify that the ICMP reply was received at port 26.
```
SEFOS-1# ping 12.0.0.100
```

Verify that the ping reply from host A to the SEFOS-1 switch is captured at host B or using the packet-capturing device, such as IXIA or SmartBits.

# tcpdump -xx -n -i eth3 icmp
...
listening on eth3, link-type EN10MB (Ethernet), capture size 96 bytes 
17:09:58.595583 IP 12.0.0.100 > 12.0.0.1: ICMP echo reply, id 0, seq 1, length 40
...
0x0010:  003c 68e6 4000 ff01 fa75 0c00 0064 0c00
17:09:58.617899 IP 12.0.0.100 > 12.0.0.1: ICMP echo reply, id 0, seq 2, length 40...
0x0030:  a5a5 a5a5 a5a5 a5a5 a5a5 a5a5 a5a5 a5a5
17:09:58.698280 IP 12.0.0.100 > 12.0.0.1: ICMP echo reply, id 0, seq 3, length 40...

Configure Port Mirroring

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