<s>
lwIP	B-Application
(	O
lightweight	O
IP	B-Protocol
)	O
is	O
a	O
widely	O
used	O
open-source	B-Application
TCP/IP	B-Protocol
stack	I-Protocol
designed	O
for	O
embedded	B-Architecture
systems	I-Architecture
.	O
</s>
<s>
lwIP	B-Application
was	O
originally	O
developed	O
by	O
Adam	O
Dunkels	O
at	O
the	O
Swedish	O
Institute	O
of	O
Computer	O
Science	O
and	O
is	O
now	O
developed	O
and	O
maintained	O
by	O
a	O
worldwide	O
network	O
of	O
developers	O
.	O
</s>
<s>
lwIP	B-Application
is	O
used	O
by	O
many	O
manufacturers	O
of	O
embedded	B-Architecture
systems	I-Architecture
,	O
including	O
Intel/Altera	O
,	O
Analog	O
Devices	O
,	O
Xilinx	O
,	O
TI	O
,	O
ST	O
and	O
Freescale	O
.	O
</s>
<s>
The	O
focus	O
of	O
the	O
lwIP	B-Application
network	O
stack	O
implementation	O
is	O
to	O
reduce	O
resource	O
usage	O
while	O
still	O
having	O
a	O
full-scale	O
TCP	B-Protocol
stack	I-Protocol
.	O
</s>
<s>
This	O
makes	O
lwIP	B-Application
suitable	O
for	O
use	O
in	O
embedded	B-Architecture
systems	I-Architecture
with	O
tens	O
of	O
kilobytes	O
of	O
free	O
RAM	O
and	O
room	O
for	O
around	O
40	O
kilobytes	O
of	O
code	O
ROM	O
.	O
</s>
<s>
Aside	O
from	O
the	O
TCP/IP	B-Protocol
stack	I-Protocol
,	O
lwIP	B-Application
has	O
several	O
other	O
important	O
parts	O
,	O
such	O
as	O
a	O
network	B-Protocol
interface	I-Protocol
,	O
an	O
operating	O
system	O
emulation	O
layer	O
,	O
buffers	O
and	O
a	O
memory	O
management	O
section	O
.	O
</s>
<s>
The	O
operating	O
system	O
emulation	O
layer	O
and	O
the	O
network	B-Protocol
interface	I-Protocol
allow	O
the	O
network	O
stack	O
to	O
be	O
transplanted	O
into	O
an	O
operating	O
system	O
,	O
as	O
it	O
provides	O
a	O
common	O
interface	O
between	O
lwIP	B-Application
code	O
and	O
the	O
operating	B-Operating_System
system	I-Operating_System
kernel	I-Operating_System
.	O
</s>
<s>
The	O
network	O
stack	O
of	O
lwIP	B-Application
includes	O
an	O
IP	B-Protocol
(	O
Internet	B-Protocol
Protocol	I-Protocol
)	O
implementation	O
at	O
the	O
Internet	B-Protocol
layer	I-Protocol
that	O
can	O
handle	O
packet	O
forwarding	O
over	O
multiple	O
network	O
interfaces	O
.	O
</s>
<s>
Both	O
IPv4	B-Protocol
and	O
IPv6	B-Protocol
are	O
supported	O
dual	O
stack	O
since	O
lwIP	B-Application
v2.0.0	O
.	O
</s>
<s>
For	O
network	O
maintenance	O
and	O
debugging	O
,	O
lwIP	B-Application
implements	O
ICMP	B-Protocol
(	O
Internet	B-Protocol
Control	I-Protocol
Message	I-Protocol
Protocol	I-Protocol
)	O
.	O
</s>
<s>
IGMP	B-Protocol
(	O
Internet	B-Protocol
Group	I-Protocol
Management	I-Protocol
Protocol	I-Protocol
)	O
is	O
supported	O
for	O
multicast	O
traffic	O
management	O
.	O
</s>
<s>
While	O
ICMPv6	B-Protocol
(	O
including	O
MLD	B-Protocol
)	O
is	O
implemented	O
to	O
support	O
the	O
use	O
of	O
IPv6	B-Protocol
.	O
</s>
<s>
lwIP	B-Application
includes	O
an	O
implementation	O
of	O
IPv4	B-Protocol
ARP	O
(	O
Address	O
Resolution	O
Protocol	O
)	O
and	O
IPv6	B-Protocol
Neighbor	I-Protocol
Discovery	I-Protocol
Protocol	O
to	O
support	O
Ethernet	O
at	O
the	O
data	B-Protocol
link	I-Protocol
layer	I-Protocol
.	O
</s>
<s>
lwIP	B-Application
may	O
also	O
be	O
operated	O
on	O
top	O
of	O
a	O
PPP	B-Protocol
(	O
Point-to-Point	B-Protocol
Protocol	I-Protocol
)	O
implementation	O
at	O
the	O
data	B-Protocol
link	I-Protocol
layer	I-Protocol
.	O
</s>
<s>
At	O
the	O
transport	B-Architecture
layer	I-Architecture
lwIP	B-Application
implements	O
TCP	B-Protocol
(	O
Transmission	B-Protocol
Control	I-Protocol
Protocol	I-Protocol
)	O
with	O
congestion	O
control	O
,	O
RTT	O
estimation	O
and	O
fast	O
recovery/fast	O
retransmit	O
.	O
</s>
<s>
UDP	B-Protocol
(	O
User	B-Protocol
Datagram	I-Protocol
Protocol	I-Protocol
)	O
is	O
implemented	O
with	O
experimental	O
UDP-Lite	B-Protocol
extensions	O
.	O
</s>
<s>
lwIP	B-Application
provides	O
a	O
specialized	O
no-copy	O
application	B-Application
programming	I-Application
interface	I-Application
(	O
API	B-Application
)	O
for	O
enhanced	O
network	O
stack	O
performance	O
.	O
</s>
<s>
The	O
Berkeley	B-Protocol
socket	I-Protocol
API	I-Protocol
is	O
optional	O
.	O
</s>
<s>
Raw	B-Protocol
sockets	I-Protocol
,	O
or	O
raw	O
pcbs	O
(	O
protocol	O
control	O
blocks	O
)	O
,	O
are	O
provided	O
depending	O
on	O
the	O
API	B-Application
used	O
.	O
</s>
<s>
At	O
the	O
application	O
layer	O
the	O
lwIP	B-Application
network	O
stack	O
may	O
be	O
supported	O
through	O
the	O
implementation	O
of	O
the	O
following	O
protocols	O
.	O
</s>
<s>
The	O
DNS	B-Protocol
(	O
Domain	B-Protocol
Name	I-Protocol
System	I-Protocol
)	O
,	O
an	O
SNMP	B-Protocol
(	O
Simple	B-Protocol
Network	I-Protocol
Management	I-Protocol
Protocol	I-Protocol
)	O
agent	O
,	O
in	O
v1	O
,	O
v2	O
or	O
v3	O
,	O
with	O
private	O
MIB	O
(	O
management	O
information	O
base	O
)	O
support	O
and	O
MIB	O
compiler	O
.	O
</s>
<s>
Operating	O
systems	O
that	O
implement	O
the	O
lwIP	B-Application
TCP/IP	B-Protocol
stack	I-Protocol
may	O
provide	O
a	O
range	O
of	O
supporting	O
clients	O
and	O
servers	O
at	O
the	O
application	O
layer	O
.	O
</s>
<s>
Such	O
as	O
an	O
IPv4	B-Protocol
DHCP	B-Protocol
(	O
Dynamic	B-Protocol
Host	I-Protocol
Configuration	I-Protocol
Protocol	I-Protocol
)	O
client	O
or	O
IPv4	B-Protocol
link-local	O
addresses	O
(	O
AutoIP	B-Protocol
)	O
.	O
</s>
<s>
Specialized	O
raw	O
API	B-Application
applications	O
include	O
:	O
an	O
HTTP	B-Protocol
server	O
,	O
a	O
SNTP	O
client	O
,	O
a	O
SMTP	B-Protocol
client	O
,	O
a	O
NetBIOS	B-Protocol
nameserver	O
,	O
a	O
mDNS	B-Protocol
responder	O
,	O
a	O
MQTT	B-Application
client	O
and	O
a	O
TFTP	B-Device
server	O
.	O
</s>
<s>
lwIP	B-Application
is	O
used	O
as	O
network	O
stack	O
in	O
ReactOS	B-Application
and	O
Genode	B-Language
and	O
can	O
be	O
used	O
in	O
Minix	B-Operating_System
and	O
GNU	B-Application
Hurd	I-Application
to	O
implement	O
network	O
servers	O
.	O
</s>
