Users Guide

Weighted ECMP for Static Routes
Dell Networking OS also supports Weighted ECMP for static routes.
You can congure weights corresponding to the paths for a static destination. If all congured paths have weights, trac distribution is
performed using the Weighted ECMP method with the RTM these passing weights to the FIB.
If all congured paths do not have weights, regular ECMP is used to determine trac paths. Also, paths that are congured with a weight
value of 0 are explicitly excluded from Weighted ECMP calculations. The RTM does not inform the FIB about these paths (next-hops).
NOTE: Dell Networking OS also supports a global conguration parameter to enable or disable Weighted ECMP for static routes
on the system.
The following example shows weighted ECMP conguration for Static Routes:
Dell(conf)#ip route 1.1.1.0/24 4.4.4.2 weight 100
Dell(conf)#ip route 1.1.1.0/24 6.6.6.2 weight 200
Dell#show running-config | grep route
ip route 1.1.1.0/24 4.4.4.2 weight 100
ip route 1.1.1.0/24 6.6.6.2 weight 200
Dell(conf)#ip route vrf test 1.1.1.0/24 4.4.4.2 weight 100
Dell(conf)#ip route vrf test 1.1.1.0/24 6.6.6.2 weight 200
Dell(conf)#
Dell(conf)#
Dell#show running-config | grep route
ip route vrf test 1.1.1.0/24 4.4.4.2 weight 100
ip route vrf test 1.1.1.0/24 6.6.6.2 weight 200
ECMP Support in L3 Host and LPM Tables
The L3 host and Longest Prex Match (LPM) tables provide ECMP next-hop forwarding for destination addresses. You can program
IPv6 /128 and IPv4 /32 route prexes to be stored in the L3 host table and move IPv6 /128 and IPv4 /32 route prexes between the host
table and the LPM route table.
By default, IPv4 route prexes are installed only in the LPM table and IPv6/128 route prexes 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 prexes 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 prexes from the host table to the LPM table, you must enable LPM CAM partitioning for
extended IPv6 prexes. See Conguring the LPM Table for IPv6 Extended Prexes for more information.
Use the ipv4 unicast-host-route or ipv6 unicast-host-route commands to program IPv4 /32 or IPv6 /128 route prexes
to be stored in the L3 host table. A warning message states that the change takes eect only when IPv4 or IPv6 route prexes are cleared
from the routing table (RTM) using the
clear ip route * command. The IPv6 /128 and IPv4 /32 route-prex entries that you move
to the host table receive ECMP handling.
To verify ECMP support for IPv6 /128 route prexes stored in the host table, use the show ipv6 cam command. The command output
includes the ECMP eld with IPv6 neighbor addresses. 1 indicates ECMP handling of destination routes.
Dell# show ipv6 cam linecard 0 port-set 0
Neighbor Mac-Addr Port Vid EC
--------------------------------------------------
[ 132] 20::1 00:00:20:d5:ec:a0 Fo 0/16 0 1
[ 132] 20::1 00:00:20:d5:ec:a1 Fo 0/24 0 1
To re-enable programming of IPv6 /128 route prexes in the LPM table, use the no ipv6 unicast-host-route command. A warning
message states that the change takes eect only when IPv4 or IPv6 route prexes are cleared from the routing table (RTM) using the
clear ip route * command.
Equal Cost Multi-Path (ECMP)
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