Using session-monitor to span ports as an aggregation tap

Like most I do not have the funds to purchase a $1000 port aggregation tap for my IDS to monitor traffic so instead I just used a 2950 Cisco Switch:

!
interface FastEthernet0/1
switchport access vlan 100
duplex full
!
interface FastEthernet0/2
switchport access vlan 100
duplex full
!
interface FastEthernet0/3
!

so the first two ports are where the traffic comes in and back out to the destination device; the third will go to my network sensor. Next let us setup the port spanning.

!
monitor session 1 source interface Fa0/1
monitor session 1 destination interface Fa0/3

Note that you can also span multiple ports or even vlans.