Administrator Guide

Equal Cost Multi-Path (ECMP)
Dell Networking OS supports equal cost multi-path (ECMP).
ECMP for Flow-Based Affinity
Dell Networking OS supports ECMP for flow-based affinity.
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 results in imbalanced loads across an ECMP/LAG when the number of
members in said ECMP/LAG is a multiple of 4.
Enabling Deterministic ECMP Next Hop
Deterministic ECMP next hop arranges all ECMPs in order before writing them into the content addressable
memory (CAM).
For example, suppose the RTM learns eight ECMPs in the order that the protocols and interfaces came up. In
this case, the forwarding information base (FIB) and CAM sort them so that the ECMPs are always arranged.
This implementation ensures that every chassis having the same prefixes orders the ECMPs the same.
With eight or less ECMPs, the ordering is lexicographic and deterministic. With more than eight ECMPs,
ordering is deterministic, but it is not in lexicographic order.
To enable deterministic ECMP next hop, use the appropriate command.
NOTE
: Packet loss might occur when you enable ip/ipv6 ecmp-deterministic for the first-time
only.
• Enable IPv4 Deterministic ECMP Next Hop.
CONFIGURATION mode.
ip ecmp-deterministic
• Enable IPv6 Deterministic ECMP Next Hop.
CONFIGURATION mode.
ipv6 ecmp-deterministic
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