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AlexFerenX
Visitor III
December 2, 2025
Question

Bridges in NAT (Routed) Operating Mode.

  • December 2, 2025
  • 2 replies
  • 434 views

Hi!

Q1. in NAT (Routed) Operarting Mode, "diagnose netlink brctl list" shows bridge information for a configured Software switch but not for a Hardware switch. Why?

Q2. Is there any alternative method to show FDB for Hardware switch?

Thanks!

2 replies

markdr_FTNT
Staff
Staff
December 3, 2025

Hi Alex,

Internally, FortiOS software switches are actually a Linux Bridge, so they are a Layer 2, kernel /CPU type construct. (The 'brctl' part of the command you mentioned refers to 'Bridge Control').

Hardware switches on the other hand are not Linux Bridges, they use Network Processors and/or ASIC chips (i.e. are entirely hardware) and therefore the bridge control diag command has no impact on them (since there is no Linux bridge).

For your second query, you can try 'get hardware nic <interface-name>'  ?  I have not validated this though.

For a managed switch, try:

diagnose switch-controller switch-info mac-table <switch_serial_number>

Hope this helps, I can create a new KB article if the information proves helpful.

Regards,
M.


 

AlexFerenX
Visitor III
December 3, 2025

Hi Mark!

> For your second query, you can try 'get hardware nic <interface-name>' 

 

the aim here isn't just to show interface (albeit, a bridge) itself, but for a "method to show FDB for Hardware switch?" - as one would get with "diagnose netlink brctl name host". How to do this?

 

Thanks!