EdgeRouter - Equal-Cost Multi Path (ECMP) Routing

Is Equal-Cost Multi Path (ECMP) Routing Supported?


Yes, EdgeOS supports Equal-Cost Multi Path (ECMP) routing. Assuming multiple routes exist for the same destination network, with same prefix and administrative distance, traffic will be balanced equally between the links. ECMP is supported per the linux kernel.

The following example shows a default route of 0.0.0.0/0 with two static routes (via 203.0.113.1, eth0 & via 192.0.2.1, eth1). The router balances between the two routes in a round-robin fashion on firmware versions 1.7 and up. On firmware versions 1.6 and lower the router would balance the traffic in a flow-hash manner.

CLI: Access the command line interface (CLI). You can do this using the CLI button in the GUI or by using a program such as PuTTY.
show ip route 
Codes: K - kernel route, C - connected, S - static, R - RIP, O - OSPF,
I - ISIS, B - BGP, > - selected route, * - FIB route

S>* 0.0.0.0/0 via 203.0.113.1, eth0
* via 192.0.2.1, eth1

The IP route summary will show the ECMP statistics.

show ip route summary 
IP routing table name is Default-IP-Routing-Table(0)
IP routing table maximum-paths   : 8
Total number of IPv4 routes      : 20
Total number of IPv4 paths       : 24
Route Source    Networks
connected       12
static          8
Total           20
FIB             0
ECMP statistics (active in ASIC):
---------------------------------
Total number of IPv4 ECMP routes : 4
Total number of IPv4 ECMP paths    : 8
Number of routes with 2 ECMP paths : 4

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