Re: Xen 4.18/ARM64 on Raspberry Pi 4B: VLAN traffic crashing Dom0

[zithro <slack@xxxxxxxxx>]

First, I need to mention I've never used bridges+VLANs this way, so I 
may miss the obvious !
I -think- it's a network problem, not a Xen one, but what do I know :)

I've often read that bridges on dom0 should have some additional params.
They would be in the iface config, around "bridge_ports", like :
    bridge_stp off      # dont use STP (spanning tree proto)
    bridge_waitport 0   # dont wait for port to be available
    bridge_fd 0         # no forward delay

You may also try to enable STP (iirc it's disabled by default on Linux 
bridges).
But TBH, I'm not sure those params will help in this case.

I've also read the VLAN 1 is a bit "special", better avoid it.
IIUC, untagged traffic would be auto tagged 1. Use ids 2/3, or 10/11, 
10/20, etc.
Other stuff to test :
- check MAC addresses
- use tcpdump/wireshark remote logging on the real NIC (enabcm6e4ei0) 
*and* the bridges, to see what really happens, maybe a network/broadcast 
storm, filling dom0 cpu/memory ?
- set "loglvl=all" to Xen cmdline to maybe get more info
- how are the interfaces configured in the domUs and in the cfg files ?
- test w/o IPv6

You could also show us the outputs of "ip a", "ip link show type bridge" 
(brctl show), etc.
PS: I guess it's only in the mail, and should be harmless, but you have 
two /eni stanzas "VLAN LAN" and "VLAN DMZ_LAN" that should be comments.
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++
zithro / Cyril