Dell Force10 S25-01-GE-24T FTOS 8.4.2.7 Command Line Reference Guide for E-Ser - Page 477

Command Modes CONFIGURATION Command History Version 8.3.1.0 Introduced on E-Series. Usage Information Deterministic ECMP sorts ECMPs in order even though RTM provides them in a random order. However, the hash algorithm uses as a seed the lower 12 bits of the chassis MAC, which yields a different hash result for every chassis. This means that for a given flow, even though the prefixes are sorted, two unrelated chassis will select different hops. FTOS provides a CLI-based solution for modifying the hash seed to ensure that on each configured system, the ECMP selection is same. When configured, the same seed is set for ECMP, LAG, and NH, and is used for incoming traffic only. Note: While the seed is stored separately on each port-pipe, the same seed is used across all CAMs. Note: You cannot separate LAG and ECMP, but you can use different algorithms across chassis with the same seed. If LAG member ports span multiple port-pipes and line cards, set the seed to the same value on each port-pipe to achieve deterministic behavior. Note: If the hash algorithm configuration is removed. Hash seed will not go to original factory default setting. ip ecmp-deterministic e Deterministic ECMP Next Hop arranges all ECMPs in order before writing them into the CAM. For example, suppose the RTM learns 8 ECMPs in the order that the protocols and interfaces came up. In this case, the 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 8 or less ECMPs, the ordering is lexicographic and deterministic. With more than 8 ECMPs, ordering is deterministic, but it is not in lexicographic order. Syntax ip ecmp-deterministic Defaults Disabled Command Modes CONFIGURATION Command History Version 8.3.1.0 Introduced on E-Series. Usage After enabling IPv6 Deterministic ECMP, traffic loss occurs for a few milliseconds while FTOS sorts Information the CAM entries. ipv6 ecmp-deterministic e Deterministic ECMP Next Hop arranges all ECMPs in order before writing them into the CAM. For example, suppose the RTM learns 8 ECMPs in the order that the protocols and interfaces came up. In this case, the 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. Equal Cost Multi-Path | 477