I need some info on line cards for a 4507. I have dual Sup IV's. I need 24 fiber gig ports. My dilemma is whether I should use a 4418 or 4 4306 line cards. If I use the 4418 is there a backplane throughput issues? Any info would be greatly appreciated.
It totally depends on the throughput you need from each port. Bear in mind each line card has access to 6Gbps of the switch fabric with a non-E 4500 chassis.
So there is no oversubscription with the 4306 ie. each port can run at full wire rate. But with the 4418 card 2 of the ports will run at wire rate and the other 16 ports are oversubscribed 4:1. Have a look at Table 2 in this doc for details -