Citrix SD-WAN

ECMP load balancing

August 24, 2022

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Equal Cost Multi-Path (ECMP) groups allow you to group multiple paths with the same cost, destination, and service. The connections or session data is load balanced across all the paths in the ECMP group depending on the type of ECMP group. For example, consider a network with two WAN links between a branch and a data center having the same route cost. Traditionally, one of the WAN links would be active and the other remains dormant acting as a fallback link. With ECMP Groups, you can group these WAN links together and allow traffic to be load balanced through both the WAN links. ECMP load balancing ensures:

Distribution of traffic over multiple equal-cost paths.
Optimal usage of available bandwidth.
Dynamic transfer of traffic to other ECMP member path, if a link fails. ECMP supports static routes on IPsec / GRE tunnels.

ECMP load balancing is supported on Virtual Paths and Intranet services. ECMP groups are defined at the global level. You can define a maximum of 254 ECMP groups in your network. The maximum number of ECMP eligible routes in an ECMP group depend on your appliance and license type. The following two types of ECMP groups are supported on Citrix SD-WAN:

Source/destination IP address: Networks where multiple clients try to connect to the same destination, the connections are load balanced across equal cost WAN links.
Session: Networks where a single client is connected to a destination and multiple sessions are spawned. The session data is load balanced across equal cost WAN links.

To monitor ECMP load balancing, in the SD-WAN UI, navigate to Monitoring > Statistics > Routes and filter the search results using the ECMP group name.

Monitoring

In the sample data, we see that all the routes within a service having a common ECMP group are part of that ECMP group. For example, 6.6.6.0/24 and 5.5.5.0/24 are in the ECMP Group Tonowhere. However, the traffic load is balanced between the services New_Intranet_Service-3 and New_Intranet_Service-4 that share a destination IP 5.5.5.0/24 and are associated to the same ECMP group.

Note

For the SIA and Zscaler service, you can load balance across two IPsec tunnel paths with ECMP (Active/Active).

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ECMP load balancing

August 24, 2022

Contributed by:

August 24, 2022

Contributed by:

ECMP load balancing

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