LACP Bandwidth Question
Posted on 2011-03-01
I want to clarify one point having to do with Link Agregation (LACP) on a Cisco Switches. Specifically I am working with a Cisco 6509 switch and 2960 switch.
I am testing throughput over an LACP Channel. If I understand the Cisco implementation of LACP correctly, if I send data between two hosts on either side of the channel, the max bandwidth will only equal the bandwidth of an individual port. I believe the reason for this is to prevent out of order packets.
So If I have four 100Mb ports set up with LACP for a LACP Channel of 400Mbps, the maximum throughput between two hosts send a stream of data will be equal to the bandwidth of one of the individual ports comprising the LACP channel (theoretically speaking, actual data throughput will be less). This value would be 100 Mbps. If I send data between two devices with Gigabit connections, though they can send up to 1 Gbps, I will only be able to achive a max throughput of 100 Mbps to to proprietary hashing algorithm used by Cisco.
In order to realize the bandwidth of LACP, you would have to have multiple data streams across the switches. Multiple hosts sending data. This just a test, but I am clarifying this point to other members of my staff that I report to.