Dell EMC SmartFabric OS10 User Guide Release 10.5.0

To increase bandwidth and for load balancing, traffic distributes across the next hops of an ECMP group or member ports of a port channel. OS10 uses a hash algorithm to determine a hash key. The egress port in a port channel or the next hop in an ECMP group is selected based on the hash key modulo the number of ports in a port channel or next hops in an ECMP group, respectively. When a member link goes down or a new member link is added, the traffic flows remap based on the new hash result.

In this section, the term, "member link" refers to either a member physical port, in the case of port channels or next hop in the case of ECMP groups.

With resilient hashing, when a member link goes down, the existing flows are not affected; they do not remap. Resilient hashing reassigns the traffic from the failed link to another member link without remapping the other existing flows. However, minimal re-mapping occurs when a new member link is added.

Resilient hashing is supported both for Port Channels and Equal Cost MultiPath Groups (ECMP). Resilient hashing is a global configuration. You can configure resilient hashing for both port channels and ECMP independently.

To enable resilient hashing for Port Channels or ECMP groups, use the following commands in CONFIGURATION mode:

OS10(config)# enhanced-hashing resilient-hashing ecmp

OS10(config)# enhanced-hashing resilient-hashing lag