Hi team,
I ran into an issue that I am apparently not the only one to have.
On one site, I am currently migrating from a Cisco edge router to a MT RB3011, v7.5 stable.
eth4+5 bundled as a LAG to a switch, with a trunk on top of it (several tagged vlans, e.g. vl100 (transit VLAN to the “inside” firewall); vlan 2 (Management)…). Traffi from/to these vlans is working perfectly. The tricky part is that I also have a legacy VLAN1 (default vlan on Cisco) which cannot be decommissioned yet due to a technical limitation.
I know it’s a bad idea to use VLAN1 (as a default VLAN but also as a rule of thumb), and it will eventually be removed a few weeks after the migration (Q1 2023 at the latest). In the meantime, I must find a way to route this traffic from VLAN1 as for the other VLANS. I also have to use the same physical cable as there are no additional ones available as the racks are in different rooms
In Cisco language, what I want is just a “native vlan 1” on the trunk. I’ve tried to configure the switchport as vlan-mode=fallback, vlan-header=add-if-missing and Default-vlan-id=1 but it cuts me off (also for the tagged vlans).
When I leave the default settings (vlan-mode=disabled, vlan-header=leave-as-is and Default-vlan-id= not set), I see packets with VLANiD=1 coming into the interface eth4 (LLDP and 802.2 traffic) but no actual L3 payload (i.e. nothing from the source IP I am trying to ping from). Tagged vlans are working fine in this case, but not my vlan 1.
I read thiese posts here which gave me some hints, but I don’t really understand the logic behind it.
viewtopic.php?p=780499
viewtopic.php?p=563675
viewtopic.php?p=958993
What am I doing wrong?
Cheers
Denis