How to map SPAN and RSPAN destination to same interface

vasanth_acharya · ‎12-15-2010

How to resolve this issue,

First we have one switch <sw1> which is connected with server (voice packet capturing server) we are able to fetch voice packets.

Now we added new switch <sw2> we configured remote span on that switch and sw1 is the destination to fetch voice packet as per server located in SW1 but destination interface for both SW1 and SW2 are same so we are getting error.

Our requirement is how to capture both switches voice packet in server.

<SW1> Configuration

Interface fastEthernet 1/0/21

Switchport access vlan 520

Switchport mode acess

Swithcport voice vlan 400

Monitor session 1 source vlan 400

Monitor session 1 destination interface fastethernet 1/0/9 - 10

In this Fas 1/0/9-10 connected server which is able to capture voice packet perfectly

Now we added one more switch

<SW2> configuration

Vlan 430

Remote-span

Interface fastEthernet 1/0/22

Switchport access vlan 520

Switchport mode acess

Swithcport voice vlan 400

Monitor session 2 source vlan 400

Monitor session 2 destination remote vlan 430

<SW1> configuration

Vlan 430

Remote-span

Monitor session 2 source remote vlan 430

Now is the issue

Monitor session 2 destination session interface fas1/0/9-10

When we mapping to destination interface in SW1 it is already mapped to SPAN so it is thronging out error.

%Interface(s) Fa1/0/9 – 10 already configured as destinations in other monitor session

Shelley Bhalla · ‎01-03-2011

You can have overlapping source ports but no overlapping destination ports. This seems to be a limitation and working as expected.

As per the cisco guide:

Destination Port

#Each local SPAN session or RSPAN destination session must have a destination port (also called a monitoring port) that receives a copy of traffic from the source ports or VLANs and sends the SPAN packets to the user, usually a network analyzer.

#A destination port has these characteristics:

#It can participate in only one SPAN session at a time (a destination port in one SPAN session cannot be a destination port for a second SPAN session)

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.2_50_se/configuration/guide/swspan.html#wp1036749

Hope it helps. Please rate and mark complete if there are no more questions.

Shelley Bhalla

Cisco TAC.