Reference Guide

Equal Cost Multi-Path (ECMP) | 329

Equal Cost Multi-Path (ECMP)

Equal Cost Multi-Path (ECMP) is supported on platforms: e c s

ECMP for Flow-based Affinity

ECMP for Flow-based Affinity is available on platforms e and

The hashing algorithm on E-Series TeraScale and E-Series ExaScale are different. Hashing on ExaScale is

based on CRC, checksum, or XOR, and the algorithm on TeraScale is based on checksum only. If

flow-based affinity is to be maintained by an ExaScale and TeraScale chassis, they must both use the same

hashing algorithm and seed value, and ECMP must deterministically choose a next hop.

• Configurable Hash Algorithm

• Configurable Hash Algorithm Seed

• Deterministic ECMP Next Hop

• Link Bundle Monitoring

Configurable Hash Algorithm

TeraScale has one algorithm that is used for LAGs, ECMP, and NH-ECMP, and ExaScale can use three

different algorithms for each of these features. To adjust the ExaScale behavior to match TeraScale, use the

following command:

Note: IPv6 /128 routes having multiple paths do not form ECMPs. The /128 route is treated as a host

entry and finds its place in the host table.

Note: Using XOR algorithms will result in imbalanced loads across an ECMP/LAG when the number of

members in said ECMP/LAG is a multiple of 4.

Task Command Syntax Command Mode

Change the ExaScale hash-algorithm for LAG, ECMP,

and NH-ECMP to match TeraScale.

hash-algorithm ecmp checksum 0

lag checksum 0 nh-ecmp checksum

CONFIGURATION