I am in the process of staging 5 new 6509s in a Lab enviornment before moving into production. I would like to connect the switches together via the GBICs on their sup modules(WS-G5486s). Is this possible? would I need special attenuating patch cords since they will be only about 5 feet apart?
Running Cisco's 1000BASE-LX/LH GBICs back-to-back requires no additional attenuation. Maximum optical transmit power of these GBICs is -3dB; maximum receive power is also -3dB. No danger of overdriving the optics here. You can use multimode or single mode fiber patches with this GBIC.
It's the 1000BASE-ZX GBICs running at 1550nm that you have to worry about. They require at least 8dB attenuation between TX port of one GBIC and the RX port of the other. (Max TX power is +5dB, Max RX power is -3dB, the difference is 8dB.)
Hope this helps.