N5600 – Verify Switching Mode

Usually you don’t have to change the hardware forwarding mode on the Nexus 5600 from the standard cut through to  mode. But if you want to run VxLan on them, you have to. The syntax to change the forwarding mode is pretty forward:

N5K1# sh run | inc hardware
hardware ethernet store-and-fwd-switching

But after the change you need to reload the switch! And here is the problem. If you don’t do the reload immediately, there is was no show command to verify in which switching mode the switch actually is. It seems this problem reached the NX-OS Developers and with Release 7.3(2)N1(1) and 7.1(5)N1(1) there is now a way to verify in which mode the Nexus is: show switching-mode 

Here is the example before the reload:

N5K1(config)# show switching-mode 
SWITCHING MODE: Cut Through

And after the reload:

N5K1# show switching-mode 
SWITCHING MODE: Store and Forward

Update:

Lukas Krattiger responded on my post on LinkedIN with the syntax for the older NX-OS Versions. It isn’t as easy rememberable (for example in the LAB Exam i would rather hope for an upgrade to 7.3.2) but as long as you can look it up in the notes, it’s working:

sh hardware internal bigsur asic 1 registers match bmin_cl_CFG_p0_port_addr

If the value ends with "00" it is store-forward
if the value ends with "ff" it is cut-through

Here on a switch where store-and-forward is enabled

N5K2# sh hardware internal bigsur asic 1 registers match bmin_cl_CFG_p0_port_addr

Slot 0 Bigsur 1 register contents:
Register Name                                          | Offset   | Value     
-------------------------------------------------------+----------+-----------
big_bmin_cl_CFG_p0_port_addr_0                         | 0x60000  | 0x800000
big_bmin_cl_CFG_p0_port_addr_1                         | 0x62000  | 0x800000
big_bmin_cl_CFG_p0_port_addr_2                         | 0x64000  | 0x800000
Done.

And here on a switch that runs in cut through

N5KX# sh hardware internal bigsur asic 1 registers match bmin_cl_CFG_p0_port_addr

Slot 0 Bigsur 1 register contents:
Register Name                                          | Offset   | Value     
-------------------------------------------------------+----------+-----------
big_bmin_cl_CFG_p0_port_addr_0                         | 0x60000  | 0x8000ff
big_bmin_cl_CFG_p0_port_addr_1                         | 0x62000  | 0x8000ff
big_bmin_cl_CFG_p0_port_addr_2                         | 0x64000  | 0x8000ff
Done.

Thanks at this point to Jakub Horbacewicz (vor the initial info for the new command) and to Lukas Krattiger for the on to check on the older hardware!