6509 port throughput, full duplex

[wilson_1234_2]

If I have a 6509 switch with a gigabit blade and I have a backup device connected to a gigabit port at 1000 full.

I have the backup source doing a disk to disk backup also on a gigabit port.

If the source is pushing to the destination, would the maximun throughput from source to destination only be approx 500Mbps?

Since the majority of the traffic would be transmit on the source and receive on the detination, is this correct?

[Joseph W. Doherty]

Full duplex supports the link's bandwidth in both directions. From one host to another, gig/full should support 1,000 Mbps. (At the same time, the two hosts could send/receive another 1,000 Mbps in the opposite direction.)

NB: Line rate, or wire speed will be higher than host transfer rate. You need to subtract out all L2 and L3 overhead. Further, different host systems and applications vary in the data rate transfer effectiveness. Gig rates also start to approach the physical hardware performance limitations of many PCs. In other words, if a backup application only reported 500 Mbps, it might be the application/host not the network itself.

[wilson_1234_2]

How do I determine what the l2, l3 overhead is?

I also wondered about the asic on the blade

48 port gigabit has 12 ports per asic

16 port gigabit has 8 ports per asic

Also wondered about potential throughput on the 6509 chassis being an issue

[Joseph W. Doherty]

re: L2 and L3 overhead, this might help: http://sd.wareonearth.com/~phil/net/overhead/

Re: questions on throughput, this whitepaper on the 6500 architecure might help: https://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/prod_white_paper0900aecd80673385.html