Lately I had to connect a Mellanox SN2100 to a Cisco SG550 via 40-10 breakout cable. There were multiple VLANs and sadly VLAN 1 for the core. The firewall connected to all networks had trunkports on all 40G’s besided VLAN 1 which was a standard access port.
Setting „switchport mode trunk“ on both ends worked for all VLANs besides VLAN 1 so I started to google around and found some articles in cisco community that „switchport mode general“ is better for multi vendor connections, so I tried this. Sadly then all other VLANs also didn’t work.
Then I started to search on Mellanox pages and found:
So there’s a mode hybrid to allow all VLANs and access mode vlan 1 for native. In Catalyst IOS this is standard mode trunk but not here. I set the mode to hybid, tagging all VLANs and access mode vlan 1. Still doesn’t work with mode general on Cisco (remember, most compatible in multi vendor) and then switched to mode trunk on SG and boom .. that’s it.
In summary, when you want to trunk between Mellanox Onyx and Cisco SMB Switches, set trunking mode to hybrid and access vlan 1 (or the native one on cisco side) and mode trunk on the SMB switch!