| Solution |
When a route is known by different protocol routes (dynamic, static), only one protocol's route will be installed in the routing table even if Equal Cost Multi-Path (ECMP) is enabled.
If a route is learned from two protocols with the same distance and metric, the route that will be installed is the latest one updated in the kernel.
In the example below, a static route to 2.2.2.2/32 was configured with an Administrative Distance of 200, the same as the iBGP distance of 200. Only the static route was installed in the routing table.
universe-esx55 # get router info routing-table all
Codes: K - kernel, C - connected, S - static, R - RIP, B - BGP
O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default
Routing table for VRF=0
S* 0.0.0.0/0 [10/0] via 10.109.31.254, port1
S 2.2.2.2/32 [200/0] is directly connected, port2
C 10.109.16.0/20 is directly connected, port1
C 10.119.0.0/20 is directly connected, port2
universe-esx55 # get router info routing-table database
Codes: K - kernel, C - connected, S - static, R - RIP, B - BGP
O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
> - selected route, * - FIB route, p - stale info
Routing table for VRF=0
S *> 0.0.0.0/0 [10/0] via 10.109.31.254, port1
S *> 2.2.2.2/32 [200/0] is directly connected, port2
B 2.2.2.2/32 [200/0] via 10.119.1.24, port2, 00:01:44
C *> 10.109.16.0/20 is directly connected, port1
C *> 10.119.0.0/20 is directly connected, port2
universe-esx55 # show router static 2
config router static
edit 2
set dst 2.2.2.2 255.255.255.255
set distance 200
set device "port2"
next
end
By default, ECMP is enabled. If the route 2.2.2.2/32 is learned by two different static route entries with the same distance, then both will be installed in the routing table. A maximum of 255 paths can be installed for a particular destination.
universe-esx55 # get router info routing-table all
Codes: K - kernel, C - connected, S - static, R - RIP, B - BGP
O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default
Routing table for VRF=0
S* 0.0.0.0/0 [10/0] via 10.109.31.254, port1
S 2.2.2.2/32 [10/0] is directly connected, port2
[10/0] is directly connected, port3
C 10.109.16.0/20 is directly connected, port1
C 10.119.0.0/20 is directly connected, port2
To disable ECMP and enforce a maximum of one route per prefix, set ecmp-max-paths to 1.
config system setting
set ecmp-max-paths 1
end
It is recommended to leave ECMP enabled in most environments. See Administration Guide: Equal Cost Muti Path (v7.6.2).
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