Multiple ports are flapping on multiple EX4400 across an EVPN/VXLAN collapse core fabric.
Switch is managed by mist, impacted ports are configured for dynamic port configuration (DPC)
Logs seen for multiple interfaces
Feb 11 21:16:21 mib2d[56543]: SNMP_TRAP_LINK_DOWN: ifIndex 646, ifAdminStatus up(1), ifOperStatus down(2), ifName ge-1/0/22
Feb 11 21:16:23 mib2d[56543]: SNMP_TRAP_LINK_UP: ifIndex 646, ifAdminStatus up(1), ifOperStatus up(1), ifName ge-1/0/22
Feb 11 21:16:31 mib2d[56543]: SNMP_TRAP_LINK_DOWN: ifIndex 541, ifAdminStatus up(1), ifOperStatus down(2), ifName ge-0/0/13
Feb 11 21:16:32 mib2d[56543]: SNMP_TRAP_LINK_DOWN: ifIndex 661, ifAdminStatus up(1), ifOperStatus down(2), ifName ge-1/0/33
Feb 11 21:16:33 mib2d[56543]: SNMP_TRAP_LINK_UP: ifIndex 541, ifAdminStatus up(1), ifOperStatus up(1), ifName ge-0/0/13
Feb 11 21:16:34 mib2d[56543]: SNMP_TRAP_LINK_UP: ifIndex 661, ifAdminStatus up(1), ifOperStatus up(1), ifName ge-1/0/33
Feb 11 21:16:37 mib2d[56543]: SNMP_TRAP_LINK_DOWN: ifIndex 646, ifAdminStatus up(1), ifOperStatus down(2), ifName ge-1/0/22
Feb 11 21:16:39 mib2d[56543]: SNMP_TRAP_LINK_UP: ifIndex 646, ifAdminStatus up(1), ifOperStatus up(1), ifName ge-1/0/22
Feb 11 21:16:43 rshd[12559]: root@re1 as root: cmd='ls -i /var/etc/filters/filter-define.conf'
Feb 11 21:16:47 mib2d[56543]: SNMP_TRAP_LINK_DOWN: ifIndex 541, ifAdminStatus up(1), ifOperStatus down(2), ifName ge-0/0/13
Feb 11 21:16:47 mib2d[56543]: SNMP_TRAP_LINK_DOWN: ifIndex 661, ifAdminStatus up(1), ifOperStatus down(2), ifName ge-1/0/33
Feb 11 21:16:49 mib2d[56543]: SNMP_TRAP_LINK_UP: ifIndex 541, ifAdminStatus up(1), ifOperStatus up(1), ifName ge-0/0/13
Feb 11 21:16:49 mib2d[56543]: SNMP_TRAP_LINK_UP: ifIndex 661, ifAdminStatus up(1), ifOperStatus up(1), ifName ge-1/0/33
DHCP requests for impacted clients are landing on the wrong vlan due to DPC and default vlan configured, causing devices to have an ip but not being able to connect to the internet properly, so the device reboots and gets into a loop due to the DHCP ip being on the wrong vlan.
Best Practice to set up a Dynamic Port Configuration
Keeping network security in mind, we recommend to create a restricted network profile, which will be assigned to unknown devices when connected to the switch ports that are enabled with DPC.
a) The advantage with this methodology would be that if devices that do not meet the DPC criteria set by the admin, they will be only provided with a profile that is restricted(non routable VLAN, guest VLAN etc)
b) When a device that meets a DPC criteria they will be provided with the corresponding port profile
c) Ensure the default/restricted VLAN for DPC configuration does not have an active DHCP server running (To avoid any stale IP issue on certain legacy devices)
Set a vlan without DHCP as default vlan on ports with DPC enabled.