SPAN / Monitor Ports - packet switched on Line Card

[greecemonkey]

Hi Forum,

I got a quick SPAN / Monitor question. I need to create a monitor session where the source is a VLAN. The question is if the L2 source and destination are switched internally on a different linecard to the the monitor destination, then does the SPAN port know about it.

I was wondering as in theory, the packet does not go on the backplane, then how does the switch monitor session know about it ??

Graham

[Jose Solano]

Hi,

In the Catalyst 6500 Series, it is important to note that egress SPAN is done on the supervisor. This allows all traffic subject to egress SPAN to be sent across the fabric to the supervisor and then to the SPAN destination port, which can use significant system resources and affect user traffic. Ingress SPAN will be done on ingress modules so SPAN performance would be the sum of all participating replication engines. The performance of the SPAN feature depends on the packet size and the type of ASIC available in the replication engine.

See this link below that contains details about the SPAN on different platforms.

http://www.cisco.com/en/US/products/hw/switches/ps708/products_tech_note09186a008015c612.shtml#topic6

Regards,