Ethernet frame type - en0 vs. et0
From: Michael Wojcik
The "en" and "et" prefixes for AIX Ethernet network interfaces
indicate the type of "framing" that surrounds higher-level protocol
data on the Ethernet medium ("wire"). The Ethernet frame is the
envelope that surrounds IP packets and equivalent messages in other
There are two kinds of Ethernet framing in common use today. The
"official" standard is IEEE 802.3 framing, but TCP/IP traffic on
Ethernet is usually carried in DIX (Digital / Intel / Xerox) type
II (usually written "DIX II" or just "DIX") frames. Other
transport-independent protocols, may use 802.3. On AIX, SNA is
probably the most common 802.3-framed protocol.
The two frame types can coexist on the wire.
Most TCP/IP stacks only support DIX framing. AIX is unusual in
supporting both DIX and 802.3 framing for TCP/IP, but there's little
point in using 802.3 for TCP/IP. The en0 interface uses DIX; the
et0 interface uses 802.3 (and so on for en1/et1, etc., if you have
You can configure TCP/IP for both en0 (DIX) and et0 (802.3), in
which case you're creating a multihomed host with only one physical
network connection. Unless you know you need TCP/IP over 802.3,
You don't need to configure TCP/IP on 802.3 to use other protocols
(eg. SNA) on 802.3.