<s>
EtherType	B-Protocol
is	O
a	O
two-octet	O
field	O
in	O
an	O
Ethernet	B-Protocol
frame	I-Protocol
.	O
</s>
<s>
It	O
is	O
used	O
to	O
indicate	O
which	O
protocol	O
is	O
encapsulated	B-Protocol
in	O
the	O
payload	O
of	O
the	O
frame	O
and	O
is	O
used	O
at	O
the	O
receiving	O
end	O
by	O
the	O
data	B-Protocol
link	I-Protocol
layer	I-Protocol
to	O
determine	O
how	O
the	O
payload	O
is	O
processed	O
.	O
</s>
<s>
The	O
same	O
field	O
is	O
also	O
used	O
to	O
indicate	O
the	O
size	O
of	O
some	O
Ethernet	B-Protocol
frames	I-Protocol
.	O
</s>
<s>
EtherType	B-Protocol
is	O
also	O
used	O
as	O
the	O
basis	O
of	O
802.1Q	O
VLAN	O
tagging	O
,	O
encapsulating	B-Protocol
packets	O
from	O
VLANs	O
for	O
transmission	O
multiplexed	O
with	O
other	O
VLAN	O
traffic	O
over	O
an	O
Ethernet	O
trunk	O
.	O
</s>
<s>
EtherType	B-Protocol
was	O
first	O
defined	O
by	O
the	O
Ethernet	B-Protocol
II	I-Protocol
framing	I-Protocol
standard	O
and	O
later	O
adapted	O
for	O
the	O
IEEE	O
802.3	O
standard	O
.	O
</s>
<s>
EtherType	B-Protocol
values	O
are	O
assigned	O
by	O
the	O
IEEE	O
Registration	O
Authority	O
.	O
</s>
<s>
In	O
modern	O
implementations	O
of	O
Ethernet	O
,	O
the	O
field	O
within	O
the	O
Ethernet	B-Protocol
frame	I-Protocol
used	O
to	O
describe	O
the	O
EtherType	B-Protocol
can	O
also	O
be	O
used	O
to	O
represent	O
the	O
size	O
of	O
the	O
payload	O
of	O
the	O
Ethernet	B-Protocol
Frame	I-Protocol
.	O
</s>
<s>
Ethernet	B-Protocol
II	I-Protocol
framing	I-Protocol
considered	O
these	O
octets	O
to	O
represent	O
EtherType	B-Protocol
while	O
the	O
original	O
IEEE	O
802.3	O
framing	O
considered	O
these	O
octets	O
to	O
represent	O
the	O
size	O
of	O
the	O
payload	O
in	O
bytes	O
.	O
</s>
<s>
In	O
order	O
to	O
allow	O
Ethernet	O
II	O
and	O
IEEE	O
802.3	O
framing	O
to	O
be	O
used	O
on	O
the	O
same	O
Ethernet	O
segment	O
,	O
a	O
unifying	O
standard	O
,	O
IEEE	O
802.3x-1997	O
,	O
was	O
introduced	O
that	O
required	O
that	O
EtherType	B-Protocol
values	O
be	O
greater	O
than	O
or	O
equal	O
to	O
1536	O
.	O
</s>
<s>
That	O
value	O
was	O
chosen	O
because	O
the	O
maximum	O
length	O
(	O
MTU	B-Protocol
)	O
of	O
the	O
data	O
field	O
of	O
an	O
Ethernet	O
802.3	O
frame	O
is	O
1500	O
bytes	O
and	O
1536	O
is	O
equivalent	O
to	O
the	O
number	O
600	O
in	O
the	O
hexadecimal	O
numeral	O
system	O
.	O
</s>
<s>
Thus	O
,	O
values	O
of	O
1500	O
and	O
below	O
for	O
this	O
field	O
indicate	O
that	O
the	O
field	O
is	O
used	O
as	O
the	O
size	O
of	O
the	O
payload	O
of	O
the	O
Ethernet	B-Protocol
frame	I-Protocol
while	O
values	O
of	O
1536	O
and	O
above	O
indicate	O
that	O
the	O
field	O
is	O
used	O
to	O
represent	O
an	O
EtherType	B-Protocol
.	O
</s>
<s>
The	O
end	O
of	O
a	O
frame	O
is	O
signaled	O
by	O
a	O
valid	O
frame	B-Protocol
check	I-Protocol
sequence	I-Protocol
followed	O
by	O
loss	O
of	O
carrier	O
or	O
by	O
a	O
special	O
symbol	O
or	O
sequence	O
in	O
the	O
line	B-Protocol
coding	I-Protocol
scheme	I-Protocol
for	O
a	O
particular	O
Ethernet	B-Protocol
physical	I-Protocol
layer	I-Protocol
,	O
so	O
the	O
length	O
of	O
the	O
frame	O
does	O
not	O
always	O
need	O
to	O
be	O
encoded	O
as	O
a	O
value	O
in	O
the	O
Ethernet	B-Protocol
frame	I-Protocol
.	O
</s>
<s>
However	O
,	O
as	O
the	O
minimum	O
payload	O
of	O
an	O
Ethernet	B-Protocol
frame	I-Protocol
is	O
46	O
bytes	O
,	O
a	O
protocol	O
that	O
uses	O
EtherType	B-Protocol
must	O
include	O
its	O
own	O
length	O
field	O
if	O
that	O
is	O
necessary	O
for	O
the	O
recipient	O
of	O
the	O
frame	O
to	O
determine	O
the	O
length	O
of	O
short	O
packets	O
(	O
if	O
allowed	O
)	O
for	O
that	O
protocol	O
.	O
</s>
<s>
802.1Q	O
VLAN	O
tagging	O
uses	O
an	O
0x8100	O
EtherType	B-Protocol
value	O
.	O
</s>
<s>
The	O
payload	O
following	O
includes	O
a	O
16-bit	O
tag	O
control	O
identifier	O
(	O
TCI	O
)	O
followed	O
by	O
an	O
Ethernet	B-Protocol
frame	I-Protocol
beginning	O
with	O
a	O
second	O
(	O
original	O
)	O
EtherType	B-Protocol
field	O
for	O
consumption	O
by	O
end	B-Protocol
stations	I-Protocol
.	O
</s>
<s>
IEEE	O
802.1ad	O
extends	O
this	O
tagging	O
with	O
further	O
nested	O
EtherType	B-Protocol
and	O
TCI	O
pairs	O
.	O
</s>
<s>
The	O
size	O
of	O
the	O
payload	O
of	O
non-standard	O
jumbo	B-Protocol
frames	I-Protocol
,	O
typically	O
~	O
9000	O
Bytes	O
long	O
,	O
falls	O
within	O
the	O
range	O
used	O
by	O
EtherType	B-Protocol
,	O
and	O
cannot	O
be	O
used	O
for	O
indicating	O
the	O
length	O
of	O
such	O
a	O
frame	O
.	O
</s>
<s>
The	O
proposition	O
to	O
resolve	O
this	O
conflict	O
was	O
to	O
substitute	O
the	O
special	O
EtherType	B-Protocol
value	O
0x8870	O
when	O
a	O
length	O
would	O
otherwise	O
be	O
used	O
.	O
</s>
<s>
However	O
,	O
the	O
proposition	O
(	O
its	O
use	O
case	O
was	O
bigger	O
packets	O
for	O
IS-IS	B-Protocol
)	O
was	O
not	O
accepted	O
and	O
it	O
is	O
defunct	O
.	O
</s>
<s>
While	O
defunct	O
,	O
this	O
draft	O
was	O
implemented	O
and	O
is	O
used	O
in	O
Cisco	O
routers	O
in	O
their	O
IS-IS	B-Protocol
implementation	O
(	O
for	O
IIH	O
Hello	O
packets	O
padding	O
)	O
.	O
</s>
<s>
With	O
the	O
advent	O
of	O
the	O
IEEE	O
802	O
suite	O
of	O
standards	O
,	O
a	O
Subnetwork	B-Protocol
Access	I-Protocol
Protocol	I-Protocol
(	O
SNAP	O
)	O
header	O
combined	O
with	O
an	O
IEEE	O
802.2	O
LLC	O
header	O
is	O
used	O
to	O
transmit	O
the	O
EtherType	B-Protocol
of	O
a	O
payload	O
for	O
IEEE	O
802	O
networks	O
other	O
than	O
Ethernet	O
,	O
as	O
well	O
as	O
for	O
non-IEEE	O
networks	O
that	O
use	O
the	O
IEEE	O
802.2	O
LLC	O
header	O
,	O
such	O
as	O
FDDI	B-Protocol
.	O
</s>
<s>
However	O
,	O
for	O
Ethernet	O
,	O
Ethernet	B-Protocol
II	I-Protocol
framing	I-Protocol
is	O
still	O
used	O
.	O
</s>
<s>
EtherTypes	B-Protocol
are	O
assigned	O
by	O
the	O
IEEE	O
Registration	O
Authority	O
.	O
</s>
<s>
Not	O
all	O
well-known	O
uses	O
of	O
EtherTypes	B-Protocol
are	O
recorded	O
in	O
the	O
IEEE	O
list	O
of	O
EtherType	B-Protocol
values	O
.	O
</s>
<s>
For	O
example	O
,	O
EtherType	B-Protocol
0x0800	O
(	O
used	O
by	O
IPv4	B-Protocol
)	O
does	O
not	O
appear	O
in	O
the	O
IEEE	O
list	O
.	O
</s>
<s>
The	O
Internet	O
Assigned	O
Numbers	O
Authority	O
has	O
a	O
separate	O
list	O
of	O
some	O
EtherType	B-Protocol
registrations	O
,	O
compiled	O
from	O
several	O
sources	O
,	O
including	O
the	O
IEEE	O
Registration	O
Authority	O
's	O
list	O
and	O
some	O
other	O
lists	O
;	O
that	O
list	O
includes	O
0800	O
.	O
</s>
<s>
+	O
EtherType	B-Protocol
values	O
for	O
some	O
notable	O
protocols	O
EtherType(hexadecimal )	O
Protocol	O
0x0800	O
Internet	B-Protocol
Protocol	I-Protocol
version	I-Protocol
4	I-Protocol
(	O
IPv4	B-Protocol
)	O
0x0806	O
Address	O
Resolution	O
Protocol	O
(	O
ARP	O
)	O
0x0842	O
Wake-on-LAN	B-Protocol
0x22F0	O
Audio	O
Video	O
Transport	O
Protocol	O
(	O
AVTP	O
)	O
0x22F3	O
IETF	B-Protocol
TRILL	I-Protocol
Protocol	I-Protocol
0x22EA	O
Stream	O
Reservation	O
Protocol	O
0x6002	O
DEC	O
MOP	B-Operating_System
RC	O
0x6003	O
DECnet	B-Protocol
Phase	O
IV	O
,	O
DNA	O
Routing	O
0x6004	O
DEC	O
LAT	B-General_Concept
0x8035	O
Reverse	B-Protocol
Address	I-Protocol
Resolution	I-Protocol
Protocol	I-Protocol
(	O
RARP	B-Protocol
)	O
0x809B	O
AppleTalk	B-Application
(	O
Ethertalk	B-Application
)	O
0x80F3	O
AppleTalk	B-Application
Address	I-Application
Resolution	I-Application
Protocol	I-Application
(	O
AARP	O
)	O
0x8100	O
VLAN-tagged	O
frame	O
(	O
IEEE	O
802.1Q	O
)	O
and	O
Shortest	B-Protocol
Path	I-Protocol
Bridging	I-Protocol
IEEE	B-Protocol
802.1aq	I-Protocol
with	O
NNI	B-Protocol
compatibility	O
0x8102	O
Simple	B-Protocol
Loop	I-Protocol
Prevention	I-Protocol
Protocol	I-Protocol
(	O
SLPP	O
)	O
0x8103	O
Virtual	B-Protocol
Link	I-Protocol
Aggregation	I-Protocol
Control	I-Protocol
Protocol	I-Protocol
(	O
VLACP	B-Protocol
)	O
0x8137	O
IPX	B-Protocol
0x8204	O
QNX	O
Qnet	O
0x86DD	O
Internet	B-Protocol
Protocol	I-Protocol
Version	I-Protocol
6	I-Protocol
(	O
IPv6	B-Protocol
)	O
0x8808	O
Ethernet	O
flow	O
control	O
0x8809	O
Ethernet	O
Slow	O
Protocols	O
such	O
as	O
the	O
Link	O
Aggregation	O
Control	O
Protocol	O
(	O
LACP	O
)	O
0x8819	O
CobraNet	B-Protocol
0x8847	O
MPLS	B-Protocol
unicast	O
0x8848	O
MPLS	B-Protocol
multicast	O
0x8863	O
PPPoE	B-Protocol
Discovery	O
Stage	O
0x8864	O
PPPoE	B-Protocol
Session	O
Stage	O
0x887B	O
HomePlug	O
1.0	O
MME	O
0x888E	O
EAP	O
over	O
LAN	O
(	O
IEEE	O
802.1X	O
)	O
0x8892	O
PROFINET	B-Protocol
Protocol	O
0x889A	O
HyperSCSI	B-Protocol
(	O
SCSI	O
over	O
Ethernet	O
)	O
0x88A2	O
ATA	B-Protocol
over	I-Protocol
Ethernet	I-Protocol
0x88A4	O
EtherCAT	B-Protocol
Protocol	O
0x88A8	O
Service	O
VLAN	O
tag	O
identifier	O
(	O
S-Tag	O
)	O
on	O
Q-in-Q	O
tunnel	O
.	O
</s>
