You can specify the IP encapsulation type as either ethernet for DIX
Ethernet-II, or ieee802 for IEEE 802.2/802.3. The default IP
encapsulation is ethernet. All systems that have Ethernet interfaces are
IEEE 802.3 compliant, but very few actually do 802.3 packet
encapsulation.
Do not change this parameter unless you know absolutely that
your Ethernet hosts are using 802.2/802.3 packet encapsulation.
An incorrect encapsulation type prevents your Remote Access
Concentrator from booting.
Nortel Networks 5399 Access Switch Hardware Installation Guide
Chapter 3
ROM Monitor Commands
3-7