Auto-sense Port States

The system uses a per-interface state to adapt to all Auto-sense events. Each state transition determines background configuration on the port. These configurations do not appear in the output of the show running-config command or in the saved configuration file but if you disable Auto-sense on the port and use the convert-to-config parameter, the dynamic configuration becomes a manual configuration and is visible in the show running-config output.

Port Down State

If you run the auto-sense enable command on a port that is disabled or has an inactive link, the port transitions to the Auto-sense Port Down state. This state transitions to the Auto-sense Wait state after the port becomes operational or the link becomes active.

Wait State

If you run the auto-sense enable command on a port that is operationally available, the port transitions to the Auto-sense Wait state and starts a 10 second timer to send the first Link Layer Discovery Protocol (LLDP) packets for loop prevention.

The port modifies outgoing LLDP packets to represent the enhanced properties of the port and analyzes incoming LLDP packets for possible transitions to advanced states like NNI, FA, or VOICE. If the port does not receive LLDP packets, the port transitions to the UNI state.

UNI State

This state grants onboarding and data connectivity to the port if you configure the onboarding I-SID or data I-SID in the global Auto-sense configuration. The system prioritizes the data I-SID over the onboarding I-SID. The system also applies the trusted and untrusted Auto-sense global configuration. As with the Wait state, the port continues to monitor received LLDP packets for transitions to other states.

The system performs the following background configurations on port x:

flex-uni enable
eapol status auto​
eapol multihost radius-non-eap-enable​
eapol multihost eap-oper-mode mhmv​
[qos 802.1p-override enable]
[access-diffserv enable]
on port X interface, if onboarding I-SID Y is configured without data I-SID:
eapol guest i-sid Y
on onboarding I-SID interface, if it is configured without data I-SID:
untagged-traffic port X
on data I-SID interface, if it is configured:
untagged-traffic port X

NNI States

The NNI states are as follows:

If, while in the Wait state, the port receives a Fabric Connect LLDP packet, the port transitions to the NNI state and adds the IS-IS SPBM instance on the interface. The system tries to establish an IS-IS adjacency and, if successful, transitions the port to the NNI IS-IS state. The port remains in the NNI IS-IS state until the adjacency fails, at which time it returns to the NNI state.

The system performs the following background configurations on port x:

isis
isis spbm 1
isis enable
[isis hello-auth …] inherited from global configuration

If the system cannot establish the adjacency, it transitions the port to the NNI onboarding state. The system creates a Switched UNI (S-UNI) with the onboarding I-SID.

The system performs the following background configurations:

flex-uni enable
isis
isis spbm 1
isis enable
[isis hello-auth …] inherited from global configuration
on onboarding i-sid interface, if it exists:
untagged-traffic port X

When a port is in the Auto-sense NNI state, if an already known system ID is discovered through LLDP on a different port, the port transitions to the NNI loop state.

The NNI loop state is similar to the NNI onboarding state except that creating a secondary S-UNI results in a loop, which occurs if the neighboring system ID is already present in the SPB forwarding information base (FIB). The system tries to establish the adjacency and transition the port to the NNI IS-IS state. If the port receives a new LLDP Fabric Connect packet, it transitions back to the NNI state. If the system cannot establish the adjacency, the port returns to the NNI loop state.

Fabric Attach States

The Fabric Attach (FA) states are as follows:

LLDP uses the FA TLV to detect FA-capable neighbors.

The port enters the FA WAP state after LLDP detects an access point, an FA client that is not another switch.

The system performs the following background configurations on port x:

flex-uni enable
eapol status auto                                 
eapol multihost radius-non-eap-enable
eapol multihost eap-oper-mode mhmv
eapol guest i-sid X
fa enable
 on onboarding i-sid interface, if it exists:
untagged-traffic port X

If LLDP detects an FA client switch that uses FA message authentication, the port transitions to the FA PROXY state.

The system performs the following background configurations on port x:

flex-uni enable
fa enable
fa message-authentication
fa management-isid

If the FA client switch does not use FA message authentication, the port transitions to the FA PROXY NOAUTH state.

The system performs the following background configurations on port x:

flex-uni enable
fa enable
on onboarding i-sid interface, if it exists:
untagged-traffic port X

Voice State

If the port detects an LLDP packet from a phone, the port transitions to the VOICE state. A global Auto-sense voice configuration is not required to transition to the VOICE state.

For more information on Auto-sense voice, see Auto-sense Voice.