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Equal Cost Multi-Path (ECMP)
This chapter describes configuring ECMP. This chapter describes configuring ECMP.
ECMP for Flow-Based Affinity
ECMP for flow-based affinity includes link bundle monitoring.
Configuring the Hash Algorithm
TeraScale has one algorithm that is used for link aggregation groups (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.
•
Change the ExaScale hash-algorithm for LAG, ECMP, and NH-ECMP to match TeraScale.
CONFIGURATION mode.
hash-algorithm ecmp checksum 0 lag checksum 0 nh-ecmp checksum 0
Dell Networking OS Behavior
: In the Dell Networking OS versions prior to 8.2.1.2, the ExaScale default hash-algorithm is 0.
Beginning with Dell Networking OS version 8.2.1.2, the default hash-algorithm is 24.
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 sorts 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
Configuring the Hash Algorithm Seed
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 behavior means that for a given flow, even though the prefixes are sorted, two unrelated chassis can select different hops.
Equal Cost Multi-Path (ECMP)
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Содержание S4048-ON
Страница 1: ...Dell Configuration Guide for the S4048 ON System 9 9 0 0 ...
Страница 146: ...Figure 14 BFD Three Way Handshake State Changes 146 Bidirectional Forwarding Detection BFD ...
Страница 477: ...Figure 68 Inspecting Configuration of LAG 10 on ALPHA Link Aggregation Control Protocol LACP 477 ...
Страница 480: ...Figure 70 Inspecting a LAG Port on BRAVO Using the show interface Command 480 Link Aggregation Control Protocol LACP ...
Страница 481: ...Figure 71 Inspecting LAG 10 Using the show interfaces port channel Command Link Aggregation Control Protocol LACP 481 ...
Страница 522: ...Figure 87 Configuring Interfaces for MSDP 522 Multicast Source Discovery Protocol MSDP ...
Страница 523: ...Figure 88 Configuring OSPF and BGP for MSDP Multicast Source Discovery Protocol MSDP 523 ...
Страница 524: ...Figure 89 Configuring PIM in Multiple Routing Domains 524 Multicast Source Discovery Protocol MSDP ...
Страница 528: ...Figure 91 MSDP Default Peer Scenario 1 528 Multicast Source Discovery Protocol MSDP ...
Страница 529: ...Figure 92 MSDP Default Peer Scenario 2 Multicast Source Discovery Protocol MSDP 529 ...
Страница 530: ...Figure 93 MSDP Default Peer Scenario 3 530 Multicast Source Discovery Protocol MSDP ...
Страница 633: ...Policy based Routing PBR 633 ...
Страница 777: ...Figure 119 Single and Double Tag TPID Match Service Provider Bridging 777 ...
Страница 778: ...Figure 120 Single and Double Tag First byte TPID Match 778 Service Provider Bridging ...