Device
C9300-48U
IOS-XE 17.3.5
Port Configuration
interface TenGigabitEthernet1/1/1
switchport mode trunk
ip arp inspection trust
channel-group 1 mode passive
ip dhcp snooping trust
!
interface TenGigabitEthernet3/1/1
switchport mode trunk
ip arp inspection trust
channel-group 1 mode passive
ip dhcp snooping trust
!
interface Port-channel1
switchport mode trunk
ip arp inspection trust
ip dhcp snooping trust
Problem
The remote switch ports are not configured with LACP or PagP, they are just standalone trunk ports, but the passive mode ports on the switch will transition into a suspended state and the switch loses network connectivity:
%ETC-5-L3DONTBNDL2: Te3/1/1 suspended: LACP currently not enabled on the remote port.
%ETC-5-L3DONTBNDL2: Te1/1/1 suspended: LACP currently not enabled on the remote port.
From the configuration guide, it appears to be written that passive mode does not attempt to engage in LACP negotiations unless it detects incoming LACP messages from its neighbor. I had interpreted this to mean that the ports would simply remain unbundled (Standalone) if no LACP neighbor was detected.
LACP Modes
LACP modes specify whether a port can send LACP packets or only receive LACP packets.
Table 2. EtherChannel LACP ModesModeDescription
active | Places a port into an active negotiating state in which the port starts negotiations with other ports by sending LACP packets. |
passive | Places a port into a passive negotiating state in which the port responds to LACP packets that it receives, but does not start LACP packet negotiation. This setting minimizes the transmission of LACP packets. |
However, there is also a reference in the guide to a change in default behaviour, unfortunately it has a bug ID that I am not permitted to view:
The independent mode behavior of ports in a port channel is changed. With CSCtn96950, by default, standalone mode is enabled. When no response is received from an LACP peer, ports in the port channel are moved to suspended state.
The wording of this is a little unclear.
Does this mean that LACP passive mode ports will become disabled (suspended) unless the neighbor device is explicitly configured with LACP active mode?
