EdgeRouter - Equal-Cost Multi Path (ECMP) Routing


Overview


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.

NOTES & REQUIREMENTS:
Applicable to the latest EdgeOS firmware on all EdgeRouter models. Please see the Related Articles below for more information.

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.

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.

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
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

Related Articles


Intro to Networking - How to Establish a Connection Using SSH


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