Slow File Transfers Between Sites in SD-WAN Environment with QoS

[banoosh]

Dear Cisco Community,

We are currently using Cisco SD-WAN in our environment, and we’ve observed slower-than-expected file transfers between sites. Our WAN links are 1Gbps, and we have Quality of Service (QoS) configured to optimize traffic. However, the issue persists.

We’re reaching out to ask for guidance on how best to investigate and diagnose this issue. Specifically, we would like to know:

What key metrics or logs should we check to identify any potential bottlenecks or misconfigurations?
Any advice or recommendations on troubleshooting and resolving this performance issue would be greatly appreciated.

[Joseph W. Doherty]

Cannot comment on SD-WAN, but I do have some experience with obtaining optimal performance using QoS.

Since you mention less than full bandwidth throughput on WAN links, possibly LFN links, there are several possibe issues with such, disregarding SD-WAN "QoS" possibly even working against you.

My recommendation would be to obtain a consulting network engineer.  (BTW, if you do go with this recommendation, carefully review the capabilities of candidates as most don't well understand the underlying issues.)