- In a virtual chassis, does the traffic entering the virtual chassis on another switch than the one with the analyzer port get mirrored?
=> yes this is supported
- Can we expect any performance degradation on the switches assuming that we only mirror a select number of VLANs?
=> the impact, especially considering your 1st question, is that VC connection (single 10GE even though 2 x 10GE ports used) will need to carry the extra traffic. Assuming you have extra bandwidth there, there should be none.
- Is there anything else we should be wary about?
=> not that I can think of, although port mirroring is designed for short-term debug use in general. Potentially a better solution is some external type of tap (Gigamon?) for perminent traffic analysis. That descision is up to you. Port mirror is obviously less expensive solution, but does affect bandwidth of some connection someplace.