SDWAN throughput between ISR 4400 - C8000v

[MsmanXY]

Dear friends, 

We are facing an issue with throughput IPsec between ISR4400- C8000v, the topology as below : 

Site A ISR4400 ---------SDWAN ---------C8000v Site B

- Version Router Edge 17.9.4a  ( latest )

- Tunnel restrict ( biz, pub )

- ipsec preference : default ( value 0 )

- Uplink ISR 4400 ( Transport ) : x2 links 500 Mbps ( biz, pub )

- Uplink C8000v ( Transport ) :  x2 links 1000 Mbps ( biz, pub ).

- License Hsec unlock , enable

The issue : When we use Iperf to  measure throughput between site A --Site B, BW record is ~  500 Mbps, ( 50 % ) of transport )

As I know that : By default SDWAN use two links and traffic will consume two link , because that I think the target bandwidth must be ~ 1000 Mbps between site A and site B.

Anyone  here is facing the same issue with me ?, let's dissucss to find the rootcause .

Thank you so much!

[Kanan Huseynli · Accepted solution]

Hi,

Go to Monitor, Network Device, select one of the devices, on the left side select Tunnels option, check only required two tunnels from the list, click on "Octets" to show diagram only octets based (data size). Time frame > real time

Run iPerf again and you will see which tunnels are getting utilized.

When you have two tunnels, still flow based ECMP is done. Traffic is going through one of the tunnels (return can be the same or another tunnel).

[MsmanXY]

Dear Kanan Huseynli, 

Thank you for your help,

When I click octets, I see Bandwith on  Tunnel Biz internet utilized over Pub internet like

700 MB - Site A- Site B Tunnel Biz

20-30 MB - Site A - To B tunnel Pub 

So, what is next step ?, ecmp is not enable by default ?, or something wrong with my ecmp ?

From Tx site ( Iperf client )

From Rx site ( Iperf server ).

Thank you so much.

[Kanan Huseynli · Accepted solution]

So, your tests utilize biz-internet based on ECMP result.

ECMP is per-flow depends on hashing result (internally selected). Try to use different server port on iperf server and let client to connect. Re-check.

Before testing you can verify routing by

show ip route vrf [subnet_X] > will show next-hop sdwan router systemIP

show sdwan bfd sessions | inc [systemIP] > should show both tunnels

show sdwan omp route [subnet_X] > should show two routes as C,I,R

[ww4686101]

Hi,

To analyze tunnel utilization, navigate to Monitor > Network Device, choose a device, then select the Tunnels option on the left. Check the boxes for the two required tunnels from the list, and click on "Octets" to display the diagram based on octets (data size). Set the time frame to real-time.

Afterward, run iPerf again to observe which tunnels are being utilized. Even with two tunnels, flow-based ECMP (Equal-Cost Multipath) is still applied. Traffic will be distributed across one of the tunnels, and the return path may be the same or another tunnel.

Hope this helps! If you found this information helpful, please consider rating and marking it as an accepted solution.