Ecmp Support In L3 Host And Lpm Tables - Dell Z9500 Configuration Manual

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Figure 40. After Polarization Effect
Traffic flow after enabling flow-based hashing
When the flow-based hashing is enabled at all the nodes in the multi-tier network, traffic distribution is balanced at all tiers of
the network nullifying the polarization effect. Traffic occurs by the randomness for the flow-based hashing algorithm across
multiple nodes in a given network.

ECMP Support in L3 Host and LPM Tables

The L3 host and Longest Prefix Match (LPM) tables provide ECMP next-hop forwarding for destination addresses. You can
program IPv6 /128 and IPv4 /32 route prefixes to be stored in the L3 host table and move IPv6 /128 and IPv4 /32 route prefixes
between the host table and the LPM route table.
By default, IPv4 route prefixes are installed only in the LPM table and IPv6/128 route prefixes are installed only in the L3 host
table. In previous releases, the IPv6 /128 entries in the host table were not supported by ECMP.
NOTE: When moving destination prefixes from the LPM to the host table, there may be a hash collision because the host
table is a hash table. In this case, a workaround does not exist for programming route entries in the host table.
NOTE: Before moving IPv6/128 route prefixes from the host table to the LPM table, you must enable LPM CAM partitioning
for extended IPv6 prefixes. See
Use the ipv4 unicast-host-route or ipv6 unicast-host-route commands to program IPv4 /32 or IPv6 /128 route
prefixes to be stored in the L3 host table. A warning message states that the change takes effect only when IPv4 or IPv6 route
prefixes are cleared from the routing table (RTM) using the clear ip route * command. The IPv6 /128 and IPv4 /32 route-
prefix entries that you move to the host table receive ECMP handling.
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Configuring the LPM Table for IPv6 Extended Prefixes
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for more information.
Equal Cost Multi-Path (ECMP) 329