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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
more information.
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.
To verify ECMP support for IPv6 /128 route prefixes stored in the host table, use the show ipv6 cam
command. The command output includes the ECMP field with IPv6 neighbor addresses. 1 indicates ECMP
handling of destination routes.
Dell# show ipv6 cam linecard 0 port-set 0
Neighbor Mac-Addr
--------------------------------------------------
[
132] 20::1 00:00:20:d5:ec:a0
[
132] 20::1 00:00:20:d5:ec:a1
To re-enable programming of IPv6 /128 route prefixes in the LPM table, use the no ipv6 unicast-host-
route command. 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.
Configuring the LPM Table for IPv6 Extended Prefixes
Port
Vid
EC
Fo 0/16
0
1
Fo 0/24
0
1
Equal Cost Multi-Path (ECMP)
for
420
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Troubleshooting
