Port Trunking and Load Balancing in Blade Switches
Hashing Algorithms for Load Balancing
The hashing algorithms use the last three least significant bits (LSB) of the destination MAC address (DA), source MAC address (SA), or destination and source MAC address (DA XOR SA) and the number of links that are available to forward frames in that port trunk group as operators.
There are three algorithms that are supported to decide the outgoing port of frames, depending on how the load balancing option is configured.
1.For the source MAC address option, N = (Last three LSB of SA) MOD (Number of links up in the port trunk)
2.For the destination MAC address option, N = (Last three LSB of DA) MOD (Number of links up in the port trunk).
3.For both source and destination MAC addresses option, N = (Last three LSB of DA XOR SA) MOD (Number of links up in the port trunk).
If N is the remainder of the equation and N is not equal to 0, then the Nth link that is up in the port trunk is the outgoing port. If N is the remainder of the equation and N is equal to 0, then N + 1 link that is up in the port trunk is the outgoing port.
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