Configure Port Mirroring

Port mirroring monitors the packets of a particular port on another port. The following example shows how to mirror all incoming packets on port 1 to port 2.

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

1. Connect to SEFOS.

   See Connect to SEFOS.

2. 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

3. 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 2, which is connected to the packet capturing device prior to the port-mirroring configuration.

4. Type the following commands on the SEFOS-1 switch to enable mirroring for incoming packets at port 1 to port 2.
   1. Enter Global Configuration mode.

      SEFOS-1# configure terminal

   2. Configure the destination interface for mirroring as port 2.

      SEFOS-1(config)# monitor session destination interface extreme-ethernet 0/2

   3. Configure the source interface for mirroring as port 1 and apply mirroring for incoming packets.

      SEFOS-1(config)# monitor session source interface extreme-ethernet 0/1 rx

   4. Exit Global Configuration mode.

      SEFOS-1(config-if)# end

   5. View the configuration details.

      SEFOS-1# show port-monitoring
       
      Port Monitoring  is enabled
      Monitor Port : Ex0/2
       
      Port        Ingress-Monitoring    Egress-Monitoring
      ----        ------------------    -----------------
      Ex0/1       Enabled               Disabled
      ...

5. Ping 12.0.0.100 and verify that the ICMP reply was received at port 2.

   SEFOS-1# ping 12.0.0.100

6. 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...

Related Information

• SEFOS Setup Tasks

• Configure ACL Filters

• Configure QoS

• Configure Rate Limiting