MPLS packets
The frame decoder recognizes an inner MPLS-encapsulated packet if the EtherType field is 0x8847 (MPLS unicast label) or 0x8848 (MPLS multicast label).
A maximum of 7 MPLS shim labels are supported.
Note: It is assumed that the next following header is IPv4 or IPv6.
MPLS length
The length of the MPLS field depends on the number of MPLS shim labels. The possible values are 0, 4, 8, 12, 16, 20, 24 and 28 bytes.