Description

Link-level type 52 is a reference to flexible-ethernet services encapsulation.

Symptoms

When you look at 'show interfaces extensive' for an ethernet interface, you will see something similar to the following:

root@Heath-re0> show interfaces ge-2/0/0 extensive
Physical interface: ge-2/0/0, Enabled, Physical link is Up
Interface index: 130, SNMP ifIndex: 1168, Generation: 133
Link-level type: Ethernet , MTU: 1514, Speed: 1000mbps, BPDU Error: None,
...

Ethernet is expected for ethernet interfaces; but sometimes you may see the following:
root@Heath-re0> show interfaces ge-2/0/0 extensive
Physical interface: ge-2/0/0, Enabled, Physical link is Up
Interface index: 130, SNMP ifIndex: 1168, Generation: 133
Link-level type: 52 , MTU: 1518, Speed: 1000mbps, BPDU Error: None,

Existing documentation states that link-level type in this output refers to the encapsulation being used on the physical interface; but does not list or describe possible values.  Most values are named, and not, therefore, in need of explanation; but a numeric value can be confusing.   Encapsulation type 52 simply means that flexible-ethernet-services encapsulation has been configured for the interface.


Solution

No action is necessary.  Encapsulation type 52 simply means that flexible-ethernet-services encapsulation has been configured for the interface.