SD-WAN: Multiple lines are used simultaneously ? (non Aggregation case)

[HT_JDC]

Dear Experts,

Are multiple lines used simultaneously at non-aggregation SD-WAN?

Here is my situation.

Between SD-WAN Fortigates, there are L2 switch which limits 10Mbps bandwidth.

iperf with UDP 10Mpbs runs at PC1 and the server is PC3.

iperf with UDP 10Mpbs runs at PC2 and the server is PC4.

However, only 5Mbps is seen at both PC3 and PC4. That is, only 1 line seems to be used.

Here is SD-WAN rule setting.

How should I do in order to use simultaneous lines at non-aggregation SD-WAN?

For information, at aggregation SD-WAN, 20Mbps seems to be used only when PC1 connects to PC3.

(PC2 and PC4 are not used.)

Thanks in advance,

[Krispin]

Hi,

If you are not using Maximize bandwidth (FortiOS 7.2 or lower) or using load-balance option within the SDWAN rule (7.4 or higher) only one line will be used. More here:

https://docs.fortinet.com/document/fortigate/7.4.5/administration-guide/708464/load-balancing-strate...

[HT_JDC]

Hello Krispin,

Thanks for your reply.

I use v7.4.5. I do not intend to select load-balance. (I select "best performance", as seen in my previous post.)

How can I configure in order to use multi lines simultaneously?

(Manual setting might be ok for me.)

Thanks in advance,

[Krispin]

With best performance you will not be able to use multiple links for load balancing. Idea behind the best performance sdwan rule is to use THE best link (only one best link available). You would need to use either lowest cost SLA or manual SDWAN rule to enable load-balance.

[HT_JDC]

Dear Krispin,

I tried both lowest cost SLA and manual with load balancing.

Here is the case for losest cost SLA.

However, the result is not good.

1) Lowest cost

both 4-5Mbps at PC3 and PC4

2) Manual

About 4-5Mbps at PC3 and about 0-1Mbps at PC4.

Any ideas to configure?

Thanks in advance,

[Krispin]

In general, it is difficult to say if the load-balancing work as you are expecting only based on 2 PCs. You can play with different hash-modes:

https://docs.fortinet.com/document/fortigate/7.4.5/administration-guide/723448/manual-strategy#LB-wi...

You need to verify if the session for the iperf or whatever are you using is really using different links or if load-balance algorithm decided to use the same link. Check the session and check the outgoing interface. And in iperf, try to use multiple parallel streams for better results.