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 Routing Example
The following example shows a default route (0.0.0.0/0) configured with two next-hop addresses. The EdgeRouter balances between the two routes in a round-robin fashion when using the EdgeOS v1.7.0 firmware and higher. On the v1.6.0 firmware version and lower the router balances the traffic in a flow-hash manner.
Verify the routing table output with the show ip route command:
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 show ip route summary command 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
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