Scenario: We found an issue with bonding (trunking/bundling/teaming/channeling) copper ethernet links between Dell PowerEdge T420 Servers running Proxmox 6 and Dell PowerConnect 55xx series switches.
ENV: Proxmox 6.1-7 on Dell PowerEdge T420 Servers
BIOS v2.6, Xeon E5 2420 CPU, Integrated BCM5720 (FW:20.8.4) Ethernet Ports 2x in proxmox bond0.
PowerConnect 5548 Series switch with firmware 184.108.40.206
It looked to be an issue of timing where interfaces on the server would come up listening for LACP control packets and time out before the switch was ready to bring up the bond.
Added slight interface monitor delays and interface up delays to the bond interface in proxmox. Bellow is a snippet.
#! /etc/network/interfaces #-------- auto bond0 iface bond0 inet manual bond-slaves eno1 eno2 bond-mode 802.3ad bond-miimon 100 bond-updelay 200 #--------