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3750G SPAN destination with ingress

I have a Cisco WS-C3750G-24PS switch running 15.0(2)SE7.  I was trying to enable ingress on a SPAN destination port.  But it didn't work as expected.


Here's the configuration on the switch:

monitor session 1 source vlan 102
monitor session 1 destination interface Gi1/0/11 ingress untagged vlan 100
interface GigabitEthernet1/0/11
 switchport access vlan 100
 switchport mode access
interface Vlan100
 ip address
mac address-table static 000c.29db.e985 vlan 100 interface GigabitEthernet1/0/11

SW#sh ip arp
Protocol  Address          Age (min)  Hardware Addr   Type   Interface
Internet           9   000c.296d.b386  ARPA   Vlan100
Internet           0   000c.29db.e985  ARPA   Vlan100

SW#sh mac addr
          Mac Address Table
Vlan    Mac Address       Type        Ports
----    -----------       --------    -----
 100    000c.298e.c512    STATIC      Gi1/0/11
 100    000c.29db.e985    STATIC      Gi1/0/11


The PC connected to port Gi1/0/11 is with IP address and MAC address 000c.29db.e985.  The PC default gateway is (SVI on switch).

When the switch is powered up and fully loaded, I cannot ping the PC from switch.  I cannot ping the switch SVI from PC.

However, if I remove the "monitor destination" command.  Try the ping a couple times.  The ping will work both ways.  Then I re-apply the "monitor destination" command.  The ping continue to work after that.

After some investigation, it looks like the "monitor destination" command somehow blocked the ARP request from the PC (to resolve the MAC address of the default gateway).  If we remove the "monitor destination" command, the ARP will go through.  The PC builds its ARP table and starts communicating with the default gateway.  Then it continues to work even after we re-apply the "monitor destination" command.

Is this an expected behavior?  Is there a better way to configure the ingress feature on a SPAN destination port?




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