97% speed decrease on SMB traffic (PANOS 8.1)

L3 Networker

97% speed decrease on SMB traffic (PANOS 8.1)

We're currently having some issues with ms-ds-smb (both v2 and v3) traffic on our PA-3020's (active/passive pair), where we are seeing a 97% speed decrease measured against direct traffic.


In order to determine the source of the issue, I have tried to disable server response inspection and all the security profiles, but I'm still getting speeds around 3-4MB/s. If I create an application override rule for tcp/445 I'm suddenly seeing around 100MB/s.


I don't really expect 100MB/s with threat protection enabled, but 3-4MB/s makes it seem like we're hitting a bug, and the firewall is far from overworked in terms of sessions and dataplane CPU usage.


Have anyone else had issues with SMB on PANOS 8.1? This has been for the last couple of versions, and we're currrently running 8.1.4.

L3 Networker

Re: 97% speed decrease on SMB traffic (PANOS 8.1)

I just set up our PA-200 lab unit to do a basic test between two Windows 7 workstations, and noticed the same on PANOS 7.1.

Have anyone managed to speed up SMB transfers on PANOS, or do we just have to deal with this?


I'm getting anywhere between 4 to 8MB/s on the firewalls, and close to 100MB/s when doing the application override.

Could anyone share some benchmarks for their own production environments? 

L7 Applicator

Re: 97% speed decrease on SMB traffic (PANOS 8.1)


I havent seen this however its probably a good candidate for a support case if you dont have one opened already. As for benchmarks, I think you will get replies that are all over the board as everyone here probably has a different setup.



L2 Linker

Re: 97% speed decrease on SMB traffic (PANOS 8.1)

Hello @as-mg


We do faced similar performance issue with SMB traffic which was improved immediately when we applied app-override. This is what TAC have to say for it. Currently we are running with App-override in place. Suggest you to submit a support case to verify the same.


"Performance issues during file transfers, improved by App-Override".

* What about inspection is causing this
==> This little snippet from Engineering may help clear up why there is slowness:

"There are differences in the way SMB content is inspected compared to other protocols such as http, ftp that can lead to decreased throughput values. SMB decoder is unable to implement suspend since file transfers are done in a block-based manner, requiring continuous CTD inspection to follow the protocol on each block. Suspending only for one file could allow evasion for all subsequent files in the same session.
For SMB, we scan every payload for content inspection and does not have any offload mechanism. Hence the reason, it is recommended to implement application override for SMB to get better throughput values"

* Have other customers reported the same or is this a known issue
==> Yes other customers has seen this behavior. This is a expected behavior due to inspection of large no packets at this time as explained above. In future it is possible there could be some enhancements in future releases. You are welcome to submit "enhancement request" with your local SE in this regards.

* What can we do to improve performance other than disabling inspection since that defeats the purpose of next gen features
==> Instead of an app-override you can also attempt disabling DSRI to see if it provides increased throughput without the application override:

L4 Transporter

Re: 97% speed decrease on SMB traffic (PANOS 8.1)

What version of 8.1 are you running....we may be running into an issue with SMB and slowness in 8.1.4   .....something about this inspection that firewall is slow at.

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