<s>
Distributed	B-Protocol
Universal	I-Protocol
Number	I-Protocol
Discovery	I-Protocol
(	O
DUNDi	B-Protocol
)	O
is	O
a	O
VoIP	B-Application
routing	O
protocol	O
that	O
provides	O
directory	O
services	O
for	O
Asterisk	B-Language
systems	O
.	O
</s>
<s>
With	O
DUNDi	B-Protocol
peered	O
nodes	O
share	O
dialplan	O
information	O
with	O
each	O
other	O
.	O
</s>
<s>
Peers	O
in	O
a	O
DUNDi	B-Protocol
cluster	O
query	O
other	O
peers	O
for	O
a	O
telephone	O
number	O
to	O
which	O
a	O
call	O
is	O
requested	O
by	O
a	O
user	O
.	O
</s>
<s>
The	O
result	O
of	O
the	O
query	O
is	O
a	O
dial	O
string	O
for	O
the	O
Asterisk	B-Language
application	O
Dial	O
.	O
</s>
<s>
The	O
protocol	O
was	O
invented	O
by	O
Mark	O
Spencer	O
,	O
the	O
author	O
of	O
Asterisk	B-Language
.	O
</s>
<s>
Asterisk	B-Language
PBX	I-Language
systems	O
that	O
use	O
DUNDi	B-Protocol
are	O
peered	O
as	O
a	O
cooperating	O
system	O
of	O
DUNDi	B-Protocol
nodes	O
,	O
each	O
having	O
certain	O
configuration	O
to	O
access	O
a	O
DUNDI	B-Protocol
instance	O
on	O
at	O
least	O
one	O
other	O
node	O
.	O
</s>
<s>
In	O
the	O
DUNDi	B-Protocol
configuration	O
one	O
can	O
limit	O
the	O
number	O
of	O
consecutive	O
lookups	O
between	O
peers	O
by	O
setting	O
the	O
TTL	O
.	O
</s>
<s>
Each	O
DUNDi	B-Protocol
peer	O
can	O
advertise	O
its	O
own	O
extensions	O
and	O
their	O
context	O
.	O
</s>
<s>
DUNDi	B-Protocol
configuration	O
assigns	O
a	O
priority	O
weight	O
to	O
each	O
advertised	O
extension	O
.	O
</s>
<s>
In	O
the	O
Asterisk	B-Language
CLI	B-Application
one	O
can	O
do	O
a	O
lookup	O
by	O
hand	O
to	O
test	O
if	O
a	O
DUNDi	B-Protocol
configuration	O
works	O
.	O
</s>
<s>
The	O
above	O
DUNDi	B-Protocol
lookup	O
tells	O
the	O
PBX	O
to	O
ask	O
the	O
known	O
peers	O
if	O
they	O
know	O
how	O
to	O
reach	O
extension	O
301	O
in	O
the	O
"	O
priv	O
"	O
network	O
.	O
</s>
<s>
When	O
no	O
context	O
is	O
given	O
with	O
a	O
lookup	O
,	O
DUNDi	B-Protocol
defaults	O
to	O
the	O
E.164	O
context	O
.	O
</s>
