<s>
The	O
Optimized	B-Protocol
Link	I-Protocol
State	I-Protocol
Routing	I-Protocol
Protocol	I-Protocol
(	O
OLSR	B-Protocol
)	O
is	O
an	O
IP	B-Protocol
routing	B-Protocol
protocol	O
optimized	O
for	O
mobile	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
,	O
which	O
can	O
also	O
be	O
used	O
on	O
other	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
.	O
</s>
<s>
OLSR	B-Protocol
is	O
a	O
proactive	O
link-state	B-Protocol
routing	I-Protocol
protocol	I-Protocol
,	O
which	O
uses	O
hello	O
and	O
topology	O
control	O
(	O
TC	O
)	O
messages	O
to	O
discover	O
and	O
then	O
disseminate	O
link	B-Protocol
state	I-Protocol
information	O
throughout	O
the	O
mobile	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
network	I-General_Concept
.	O
</s>
<s>
Link-state	B-Protocol
routing	I-Protocol
protocols	I-Protocol
such	O
as	O
Open	B-Protocol
Shortest	I-Protocol
Path	I-Protocol
First	I-Protocol
(	O
OSPF	B-Protocol
)	O
and	O
Intermediate	B-Protocol
System	I-Protocol
to	I-Protocol
Intermediate	I-Protocol
System	I-Protocol
(	O
IS-IS	B-Protocol
)	O
elect	O
a	O
designated	O
router	O
on	O
every	O
link	O
to	O
perform	O
flooding	O
of	O
topology	O
information	O
.	O
</s>
<s>
In	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
,	O
there	O
is	O
different	O
notion	O
of	O
a	O
link	O
,	O
packets	O
can	O
and	O
do	O
go	O
out	O
the	O
same	O
interface	O
;	O
hence	O
,	O
a	O
different	O
approach	O
is	O
needed	O
in	O
order	O
to	O
optimize	O
the	O
flooding	O
process	O
.	O
</s>
<s>
Using	O
Hello	O
messages	O
the	O
OLSR	B-Protocol
protocol	O
at	O
each	O
node	O
discovers	O
2-hop	O
neighbor	O
information	O
and	O
performs	O
a	O
distributed	O
election	O
of	O
a	O
set	O
of	O
multipoint	O
relays	O
(	O
MPRs	O
)	O
.	O
</s>
<s>
This	O
functioning	O
of	O
MPRs	O
makes	O
OLSR	B-Protocol
unique	O
from	O
other	O
link	B-Protocol
state	I-Protocol
routing	I-Protocol
protocols	I-Protocol
in	O
a	O
few	O
different	O
ways	O
:	O
The	O
forwarding	O
path	O
for	O
TC	O
messages	O
is	O
not	O
shared	O
among	O
all	O
nodes	O
but	O
varies	O
depending	O
on	O
the	O
source	O
,	O
only	O
a	O
subset	O
of	O
nodes	O
source	O
link	B-Protocol
state	I-Protocol
information	O
,	O
not	O
all	O
links	O
of	O
a	O
node	O
are	O
advertised	O
but	O
only	O
those	O
that	O
represent	O
MPR	O
selections	O
.	O
</s>
<s>
Since	O
link-state	B-Protocol
routing	I-Protocol
requires	O
the	O
topology	O
database	O
to	O
be	O
synchronized	O
across	O
the	O
network	O
,	O
OSPF	B-Protocol
and	O
IS-IS	B-Protocol
perform	O
topology	O
flooding	O
using	O
a	O
reliable	O
algorithm	O
.	O
</s>
<s>
Such	O
an	O
algorithm	O
is	O
very	O
difficult	O
to	O
design	O
for	O
ad	B-General_Concept
hoc	I-General_Concept
wireless	I-General_Concept
networks	I-General_Concept
,	O
so	O
OLSR	B-Protocol
does	O
n't	O
bother	O
with	O
reliability	O
;	O
it	O
simply	O
floods	O
topology	O
data	O
often	O
enough	O
to	O
make	O
sure	O
that	O
the	O
database	O
does	O
not	O
remain	O
unsynchronized	O
for	O
extended	O
periods	O
of	O
time	O
.	O
</s>
<s>
They	O
also	O
have	O
the	O
main	O
role	O
in	O
routing	B-Protocol
and	O
selecting	O
the	O
proper	O
route	O
from	O
any	O
source	O
to	O
any	O
desired	O
destination	O
node	O
.	O
</s>
<s>
MPRs	O
advertise	O
link-state	B-Protocol
information	O
for	O
their	O
MPR	O
selectors	O
(	O
a	O
node	O
selected	O
as	O
a	O
MPR	O
)	O
periodically	O
in	O
their	O
control	O
messages	O
.	O
</s>
<s>
Having	O
the	O
routes	O
available	O
within	O
the	O
standard	O
routing	B-Protocol
table	O
can	O
be	O
useful	O
for	O
some	O
systems	O
and	O
network	O
applications	O
as	O
there	O
is	O
no	O
route	O
discovery	O
delay	O
associated	O
with	O
finding	O
a	O
new	O
route	O
.	O
</s>
<s>
The	O
routing	B-Protocol
overhead	O
generated	O
,	O
while	O
generally	O
greater	O
than	O
that	O
of	O
a	O
reactive	O
protocol	O
,	O
does	O
not	O
increase	O
with	O
the	O
number	O
of	O
routes	O
being	O
created	O
.	O
</s>
<s>
Default	O
and	O
network	O
routes	O
can	O
be	O
injected	O
into	O
the	O
system	O
by	O
HNA	O
messages	O
allowing	O
for	O
connection	O
to	O
the	O
internet	O
or	O
other	O
networks	O
within	O
the	O
OLSR	B-Protocol
MANET	B-General_Concept
cloud	O
.	O
</s>
<s>
The	O
original	O
definition	O
of	O
OLSR	B-Protocol
does	O
not	O
include	O
any	O
provisions	O
for	O
sensing	O
of	O
link	O
quality	O
;	O
it	O
simply	O
assumes	O
that	O
a	O
link	O
is	O
up	O
if	O
a	O
number	O
of	O
hello	O
packets	O
have	O
been	O
received	O
recently	O
.	O
</s>
<s>
Implementations	O
such	O
as	O
the	O
open	O
source	O
OLSRd	B-Protocol
(	O
commonly	O
used	O
on	O
Linux-based	O
mesh	O
routers	O
)	O
have	O
been	O
extended	O
(	O
as	O
of	O
v	O
.	O
0.4.8	O
)	O
with	O
link	O
quality	O
sensing	O
.	O
</s>
<s>
Being	O
a	O
proactive	O
protocol	O
,	O
OLSR	B-Protocol
uses	O
power	O
and	O
network	O
resources	O
in	O
order	O
to	O
propagate	O
data	O
about	O
possibly	O
unused	O
routes	O
.	O
</s>
<s>
While	O
this	O
is	O
not	O
a	O
problem	O
for	O
wired	O
access	O
points	O
,	O
and	O
laptops	O
,	O
it	O
makes	O
OLSR	B-Protocol
unsuitable	O
for	O
sensor	O
networks	O
that	O
try	O
to	O
sleep	O
most	O
of	O
the	O
time	O
.	O
</s>
<s>
For	O
small	O
scale	O
wired	O
access	O
points	O
with	O
low	O
CPU	B-General_Concept
power	O
,	O
the	O
open	O
source	O
project	O
showed	O
that	O
large	O
scale	O
mesh	O
networks	O
can	O
run	O
with	O
OLSRd	B-Protocol
on	O
thousands	O
of	O
nodes	O
with	O
very	O
little	O
CPU	B-General_Concept
power	O
on	O
embedded	O
devices	O
.	O
</s>
<s>
Being	O
a	O
link-state	B-Protocol
protocol	I-Protocol
,	O
OLSR	B-Protocol
requires	O
a	O
reasonably	O
large	O
amount	O
of	O
bandwidth	O
and	O
CPU	B-General_Concept
power	O
to	O
compute	O
optimal	O
paths	O
in	O
the	O
network	O
.	O
</s>
<s>
In	O
the	O
typical	O
networks	O
where	O
OLSR	B-Protocol
is	O
used	O
(	O
which	O
rarely	O
exceed	O
a	O
few	O
hundreds	O
of	O
nodes	O
)	O
,	O
this	O
does	O
not	O
appear	O
to	O
be	O
a	O
problem	O
.	O
</s>
<s>
By	O
only	O
using	O
MPRs	O
to	O
flood	O
topology	O
information	O
,	O
OLSR	B-Protocol
removes	O
some	O
of	O
the	O
redundancy	O
of	O
the	O
flooding	O
process	O
,	O
which	O
may	O
be	O
a	O
problem	O
in	O
networks	O
with	O
moderate	O
to	O
large	O
packet	O
loss	O
rates	O
–	O
however	O
the	O
MPR	O
mechanism	O
is	O
self-pruning	O
(	O
which	O
means	O
that	O
in	O
case	O
of	O
packet	O
losses	O
,	O
some	O
nodes	O
that	O
would	O
not	O
have	O
retransmitted	O
a	O
packet	O
,	O
may	O
do	O
so	O
)	O
.	O
</s>
<s>
OLSR	B-Protocol
makes	O
use	O
of	O
"	O
Hello	O
"	O
messages	O
to	O
find	O
its	O
one	O
hop	O
neighbors	O
and	O
its	O
two	O
hop	O
neighbors	O
through	O
their	O
responses	O
.	O
</s>
<s>
OLSR	B-Protocol
uses	O
topology	O
control	O
(	O
TC	O
)	O
messages	O
along	O
with	O
MPR	O
forwarding	O
to	O
disseminate	O
neighbor	O
information	O
throughout	O
the	O
network	O
.	O
</s>
<s>
Host	O
and	O
network	O
association	O
(	O
HNA	O
)	O
messages	O
are	O
used	O
by	O
OLSR	B-Protocol
to	O
disseminate	O
network	O
route	O
advertisements	O
in	O
the	O
same	O
way	O
TC	O
messages	O
advertise	O
host	O
routes	O
.	O
</s>
<s>
The	O
problem	O
of	O
routing	B-Protocol
in	O
ad	B-General_Concept
hoc	I-General_Concept
wireless	I-General_Concept
networks	I-General_Concept
is	O
actively	O
being	O
researched	O
,	O
and	O
OLSR	B-Protocol
is	O
but	O
one	O
of	O
several	O
proposed	O
solutions	O
.	O
</s>
<s>
To	O
many	O
,	O
it	O
is	O
not	O
clear	O
whether	O
a	O
whole	O
new	O
protocol	O
is	O
needed	O
,	O
or	O
whether	O
OSPF	B-Protocol
could	O
be	O
extended	O
with	O
support	O
for	O
wireless	O
interfaces	O
.	O
</s>
<s>
In	O
bandwidth	O
-	O
and	O
power-starved	O
environments	O
,	O
it	O
is	O
interesting	O
to	O
keep	O
the	O
network	O
silent	O
when	O
there	O
is	O
no	O
traffic	O
to	O
be	O
routed	B-Protocol
.	O
</s>
<s>
Reactive	O
routing	B-Protocol
protocols	O
do	O
not	O
maintain	O
routes	O
,	O
but	O
build	O
them	O
on	O
demand	O
.	O
</s>
<s>
As	O
link-state	B-Protocol
protocols	I-Protocol
require	O
database	O
synchronisation	O
,	O
such	O
protocols	O
typically	O
use	O
the	O
distance	O
vector	O
approach	O
,	O
as	O
in	O
AODV	B-Device
and	O
DSDV	B-Protocol
,	O
or	O
more	O
ad	O
hoc	O
approaches	O
that	O
do	O
not	O
necessarily	O
build	O
optimal	O
paths	O
,	O
such	O
as	O
Dynamic	B-Device
Source	I-Device
Routing	I-Device
.	O
</s>
<s>
For	O
more	O
information	O
see	O
the	O
list	B-Protocol
of	I-Protocol
ad	I-Protocol
hoc	I-Protocol
routing	I-Protocol
protocols	I-Protocol
.	O
</s>
<s>
These	O
components	O
are	O
being	O
designed	O
to	O
be	O
common	O
among	O
next	O
generation	O
IETF	O
MANET	B-General_Concept
protocols	O
.	O
</s>
<s>
Differences	O
in	O
the	O
handling	O
of	O
multiple	O
address	O
and	O
interface	O
enabled	O
nodes	O
is	O
also	O
present	O
between	O
OLSR	B-Protocol
and	O
OLSRv2	O
.	O
</s>
<s>
–	O
Downloadable	O
code	O
for	O
OLSR	B-Protocol
on	O
Linux	B-Application
,	O
Windows	O
,	O
Mac	O
OS	O
X	O
,	O
FreeBSD	O
,	O
NetBSD	O
and	O
OpenBSD	B-Operating_System
systems	O
.	O
</s>
<s>
–	O
Open	O
source	O
code	O
of	O
NRL-OLSR	O
.	O
</s>
<s>
Works	O
on	O
Windows	O
,	O
MacOS	O
,	O
Linux	B-Application
,	O
and	O
various	O
embedded	O
PDA	O
systems	O
such	O
as	O
Arm/Zaurus	O
and	O
PocketPC	O
as	O
well	O
as	O
simulation	O
environments	O
ns2	B-Language
and	O
OPNET.	O
,	O
</s>
<s>
–	O
Created	O
by	O
MOVIQUITY	O
and	O
based	O
on	O
studies	O
within	O
the	O
project	O
Workpad	O
,	O
it	O
offers	O
a	O
code	O
in	O
C#	O
to	O
deploy	O
a	O
MANET	B-General_Concept
(	O
Ad	O
Hoc	O
,	O
Meshnet	O
)	O
with	O
protocol	O
OLSR	B-Protocol
.	O
</s>
