<s>
Generic	B-Protocol
Stream	I-Protocol
Encapsulation	I-Protocol
,	O
or	O
GSE	O
for	O
short	O
,	O
is	O
a	O
Data	B-Protocol
link	I-Protocol
layer	I-Protocol
protocol	O
defined	O
by	O
DVB	B-Application
.	O
</s>
<s>
GSE	O
provides	O
means	O
to	O
carry	O
packet	B-Protocol
oriented	O
protocols	O
such	O
as	O
IP	B-Protocol
on	O
top	O
of	O
uni-directional	O
physical	B-Application
layers	I-Application
such	O
as	O
DVB-S2	O
,	O
DVB-T2	B-Protocol
and	O
DVB-C2	B-Device
.	O
</s>
<s>
GSE	O
provides	O
additional	O
features	O
beyond	O
the	O
pure	O
carriage	O
of	O
IP	B-Protocol
datagrams	B-Protocol
that	O
increase	O
the	O
protocol	O
flexibility	O
and	O
applicability	O
.	O
</s>
<s>
Support	O
for	O
multi-protocol	O
encapsulation	O
(	O
IPv4	B-Protocol
,	O
IPv6	B-Protocol
,	O
MPEG	O
,	O
ATM	O
,	O
Ethernet	O
,	O
802.1pQ	O
VLANs	B-General_Concept
,	O
etc	O
.	O
)	O
</s>
<s>
Transparency	O
to	O
network	B-Application
layer	I-Application
functions	O
,	O
including	O
IP	B-Protocol
encryption	O
and	O
IP	B-Protocol
header	B-Protocol
compression	I-Protocol
.	O
</s>
<s>
In	O
addition	O
to	O
the	O
6-byte	O
MAC	O
address	O
(	O
including	O
multicast	O
and	O
unicast	B-Protocol
)	O
,	O
it	O
supports	O
a	O
MAC	O
address-less	O
mode	O
,	O
and	O
an	O
optional	O
3-byte	O
address	O
mode	O
.	O
</s>
<s>
A	O
mechanism	O
for	O
fragmenting	O
IP	B-Protocol
datagrams	B-Protocol
or	O
other	O
network	B-Application
layer	I-Application
packets	B-Protocol
over	O
Base	B-Algorithm
Band	I-Algorithm
frames	O
to	O
support	O
ACM/VCM	O
.	O
</s>
<s>
Support	O
for	O
hardware	O
filtering	B-Application
.	O
</s>
<s>
Layer	B-Protocol
2	I-Protocol
security	O
,	O
IP	B-Protocol
Header	B-Protocol
Compression	I-Protocol
,	O
etc	O
.	O
</s>
<s>
IP	B-Protocol
datagrams	B-Protocol
,	O
Ethernet	O
Frames	O
,	O
or	O
other	O
network	B-Application
layer	I-Application
packets	B-Protocol
are	O
encapsulated	O
in	O
one	O
or	O
more	O
GSE	O
Packets	B-Protocol
.	O
</s>
<s>
The	O
payload	O
frame	O
may	O
be	O
encapsulated	O
in	O
a	O
single	O
GSE	O
Packet	B-Protocol
or	O
sliced	O
into	O
fragments	O
and	O
encapsulated	O
in	O
several	O
GSE	O
Packets	B-Protocol
.	O
</s>
<s>
GSE	O
Packets	B-Protocol
have	O
in	O
general	O
variable	O
length	O
,	O
in	O
order	O
to	O
match	O
the	O
input	O
IP	B-Protocol
traffic	O
with	O
minimum	O
overhead	O
.	O
</s>
<s>
GSE	O
Packets	B-Protocol
may	O
be	O
sent	O
in	O
different	O
Base	B-Algorithm
Band	I-Algorithm
frames	O
,	O
not	O
necessarily	O
consecutive	O
or	O
with	O
the	O
same	O
transmission	O
parameters	O
(	O
modulation	O
format	O
,	O
coding	O
rate	O
)	O
.	O
</s>
<s>
No	O
constraint	O
on	O
the	O
GSE	O
Packet	B-Protocol
position	O
within	O
the	O
Base	B-Algorithm
Band	I-Algorithm
frame	O
is	O
assumed	O
.	O
</s>
<s>
However	O
,	O
GSE	O
Packets	B-Protocol
may	O
not	O
be	O
reordered	O
between	O
the	O
encapsulator	O
and	O
the	O
de-encapsulator	O
.	O
</s>
<s>
In	O
general	O
,	O
a	O
Base	B-Algorithm
Band	I-Algorithm
frame	O
can	O
contain	O
more	O
than	O
a	O
single	O
GSE	O
Packet	B-Protocol
.	O
</s>
<s>
Base	B-Algorithm
Band	I-Algorithm
frames	O
may	O
have	O
fixed	O
,	O
or	O
variable	O
length	O
.	O
</s>
<s>
GSE	O
does	O
not	O
provide	O
a	O
mechanism	O
for	O
integrity	O
check	O
of	O
single	O
GSE	O
Packet	B-Protocol
.	O
</s>
<s>
GSE	O
relies	O
on	O
the	O
physical	B-Application
layer	I-Application
being	O
able	O
to	O
ensure	O
the	O
required	O
error	O
detection	O
and/or	O
correction	O
probability	O
.	O
</s>
<s>
The	O
GSE	O
Packet	B-Protocol
header	O
is	O
highly	O
dynamic	O
and	O
provides	O
for	O
many	O
options	O
.	O
</s>
<s>
On	O
DVB-S2	O
,	O
DVB-T2	B-Protocol
,	O
and	O
DVB-C2	B-Device
the	O
ACM/VCM	O
modes	O
may	O
cause	O
the	O
Base	B-Algorithm
Band	I-Algorithm
frames	O
to	O
vary	O
in	O
size	O
depending	O
on	O
the	O
transmission	O
conditions	O
.	O
</s>
<s>
occur	O
when	O
large	O
fragments	O
have	O
been	O
prepared	O
while	O
transmission	O
conditions	O
were	O
fine	O
,	O
but	O
suddenly	O
the	O
conditions	O
deteriorate	O
,	O
and	O
only	O
small	O
Base	B-Algorithm
Band	I-Algorithm
frames	O
are	O
available	O
.	O
</s>
<s>
The	O
"	O
Label	O
Type	O
"	O
(	O
LT	O
)	O
bits	O
determine	O
how	O
the	O
GSE	O
packet	B-Protocol
address	O
is	O
encoded	O
according	O
to	O
the	O
following	O
table	O
:	O
</s>
<s>
+	O
Addressing	O
Mode	O
LT	O
bits	O
Addressing	O
mode	O
00	O
Indicates	O
that	O
a	O
6	O
bytes	O
label	O
is	O
present	O
and	O
shall	O
be	O
used	O
for	O
filtering	B-Application
.	O
</s>
<s>
01	O
Indicates	O
that	O
a	O
3	O
bytes	O
label	O
is	O
present	O
and	O
shall	O
be	O
used	O
for	O
filtering	B-Application
.	O
</s>
<s>
All	O
receivers	O
shall	O
process	O
this	O
packet	B-Protocol
.	O
</s>
<s>
11	O
Label	O
re-use	O
:	O
no	O
label	O
is	O
present	O
;	O
the	O
label	O
is	O
the	O
same	O
as	O
the	O
previous	O
GSE	O
packet	B-Protocol
in	O
the	O
same	O
base	B-Algorithm
band	I-Algorithm
frame	O
.	O
</s>
<s>
LT	O
=	O
11	O
is	O
also	O
used	O
for	O
intermediate	O
and	O
end	O
packets	B-Protocol
(	O
i.e.	O
</s>
<s>
LT	O
=	O
11	O
shall	O
not	O
be	O
used	O
for	O
the	O
first	O
GSE	O
packet	B-Protocol
in	O
a	O
base	B-Algorithm
band	I-Algorithm
frame	O
with	O
Start	O
bit	O
1	O
.	O
</s>
<s>
Each	O
GSE	O
Packet	B-Protocol
containing	O
the	O
last	O
fragment	O
for	O
a	O
payload	O
frame	O
,	O
carries	O
a	O
CRC-32	O
checksum	O
over	O
the	O
payload	O
frame	O
.	O
</s>
