Want to apply load balance algorithm on Fortigate SDWAN..

[Shantilal1998]

Hi Team,

I have two ISP links one is 25 Mbps & second is 15 Mbps & want to load balance to utilize both the bandwidth.

How i can achieve this using the sdwan algorithms & which algorithm i need to select here. Thanks.

[saneeshpv_FTNT]

Hi @Shantilal1998

If its simply loadbalancing, you can choose Volume based, based on the available bandwidth. But I still recommend you can follow below article to decide what algorithm you can choose from all the available option and its purely based on your network requirements. 

https://docs.fortinet.com/document/fortigate/7.4.1/administration-guide/683285/selecting-the-implici...

In addition to this you can also make use of SDWAN rules with SLA, if you wish to send certain traffic only over a specific link all the time and if there is a SLA violation for example, High latency in that link, you can switch to the next available link. Even in these rules, you have different methods to choose from the available options. 

https://docs.fortinet.com/document/fortigate/6.4.2/sd-wan-deployment-with-zscaler/256930/configuring...

https://docs.fortinet.com/document/fortigate/7.0.0/sd-wan-sd-branch-deployment-guide/727336/creating... 

Hope this helps !

Regards,

Saneesh

[pginete]

You can use session-based. Then configure 60 on the weight value of the 25 Mbps ISP while 40 on the 15 Mbps ISP.

60 percent of the sessions will go through the 25 Mbps ISP while 40 percent of sessions will go through the 15 Mbps ISP.

You may check this docs link https://docs.fortinet.com/document/fortigate/7.0.13/administration-guide/216765/implicit-rule under Example 2 for more details.

[Shantilal1998]

But will it work for UDP traffic.

[saneeshpv_FTNT]

I should work for UDP as well. 

As @pginete mentioned, you can even choose session based, but keep in mind that Fortigate will not consider traffic on an interface (self traffic) when using session based method, but with volume based it tracks all the bytes on the interface. Also with session based method, traffic volume can change depending on the type and duration of the session but in volume, it is based on the measured volume of traffic and also during the time of exceeding volume threshold, existing session will still stay in the same path and won't get dirty. 

[Shantilal1998]

Ok.. I have a another question & different topic. If a performance SLA is not attached with any SDWAN rule then will it work to disable the static routes based on the threshold.

[hbac]

Hi @Shantilal1998,

If the performance SLA is configured correctly, it will update the static route based on threshold. It has nothing to do with SDWAN rules. 

Regards,