Setup Guide
Weighted ECMP for Static Routes
Dell Networking OS also supports Weighted ECMP for static routes.
You can congure weights corresponding to the paths for a static destination. If all congured paths have weights, trac distribution is
performed using the Weighted ECMP method with the RTM these passing weights to the FIB.
If all congured paths do not have weights, regular ECMP is used to determine trac paths. Also, paths that are congured 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 conguration parameter to enable or disable Weighted ECMP for static routes
on the system.
The following example shows weighted ECMP conguration 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 Prex Match (LPM) tables provide ECMP next-hop forwarding for destination addresses. You can program
IPv6 /128 and IPv4 /32 route prexes to be stored in the L3 host table and move IPv6 /128 and IPv4 /32 route prexes between the host
table and the LPM route table.
By default, IPv4 route prexes are installed only in the LPM table and IPv6/128 route prexes 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 prexes 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 prexes from the host table to the LPM table, you must enable LPM CAM partitioning for
extended IPv6 prexes. See Conguring the LPM Table for IPv6 Extended Prexes for more information.
Use the ipv4 unicast-host-route or ipv6 unicast-host-route commands to program IPv4 /32 or IPv6 /128 route prexes
to be stored in the L3 host table. A warning message states that the change takes eect only when IPv4 or IPv6 route prexes are cleared
from the routing table (RTM) using the
clear ip route * command. The IPv6 /128 and IPv4 /32 route-prex entries that you move
to the host table receive ECMP handling.
To verify ECMP support for IPv6 /128 route prexes 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 prexes in the LPM table, use the no ipv6 unicast-host-route command. A warning
message states that the change takes eect only when IPv4 or IPv6 route prexes are cleared from the routing table (RTM) using the
clear ip route * command.
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Equal Cost Multi-Path (ECMP)