2.1.e (iii) Load-balancing

2.1.e (iii) Load-balancing

Flows can become polarized (like CEF polarization) to a specific link if ther flow is not classified as diverse. So depending on the etherchannel load balancing hashing algorithm, we might get polarization. By default Cisco devices just hash the flow based on the source mac address, which is susceptible to polarization, thus this should be changed to something like src+dst ip and src + dst ports.

Note: changing this value is only locally significant and does not need to match. In fact some people choose to have it not match when they don’t have any good load balancing options.

Here’s how we can change that algorithm.config: port-channel load-balance <method>
port-channel load-balance src-ip
port-channel load-balance dst-ip
port-channel load-balance src-mac
port-channel load-balance dst-mac
port-channel load-balance src-dst-ip
port-channel load-balance src-dst-mac

verify: show etherchannel load-balance

We can test our load balancing further via a test command:
test etherchannel load-balance int port-channl <num> <ip or mac>

basically CEF handles L3 load balancing, and a different hashing bucket handles the L2 load balancing