<s>
BIRD	O
(	O
recursive	O
acronym	O
for	O
BIRD	B-Protocol
Internet	I-Protocol
Routing	I-Protocol
Daemon	I-Protocol
)	O
is	O
an	O
open-source	B-Application
implementation	O
for	O
routing	B-Protocol
Internet	B-Protocol
Protocol	I-Protocol
packets	O
on	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
.	O
</s>
<s>
It	O
was	O
developed	O
as	O
a	O
school	O
project	O
at	O
the	O
Faculty	O
of	O
Mathematics	O
and	O
Physics	O
,	O
Charles	O
University	O
,	O
Prague	O
,	O
and	O
is	O
distributed	O
under	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
.	O
</s>
<s>
BIRD	O
supports	O
Internet	B-Protocol
Protocol	I-Protocol
version	I-Protocol
4	I-Protocol
and	O
version	B-Protocol
6	I-Protocol
by	O
running	O
separate	O
daemons	B-Operating_System
.	O
</s>
<s>
It	O
establishes	O
multiple	O
routing	B-Protocol
tables	O
,	O
and	O
uses	O
BGP	B-Protocol
,	O
RIP	B-Protocol
,	O
and	O
OSPF	B-Protocol
routing	B-Protocol
protocols	O
,	O
as	O
well	O
as	O
statically	O
defined	O
routes	O
.	O
</s>
<s>
Its	O
design	O
differs	O
significantly	O
from	O
GNU	B-Application
Zebra	I-Application
,	O
Quagga	B-Protocol
and	O
FRRouting	B-Protocol
.	O
</s>
<s>
Currently	O
BIRD	O
is	O
included	O
in	O
many	O
Linux	O
distributions	O
,	O
such	O
as	O
Debian	O
,	O
Ubuntu	B-Operating_System
and	O
Fedora	O
.	O
</s>
<s>
BIRD	O
is	O
used	O
in	O
several	O
Internet	B-Protocol
exchanges	I-Protocol
,	O
such	O
as	O
the	O
London	O
Internet	B-Protocol
Exchange	I-Protocol
(	O
LINX	O
)	O
,	O
LONAP	O
,	O
DE-CIX	O
and	O
MSK-IX	O
as	O
a	O
route	O
server	O
,	O
where	O
it	O
replaced	O
Quagga	B-Protocol
because	O
of	O
its	O
scalability	O
issues	O
.	O
</s>
<s>
According	O
to	O
the	O
2012	O
Euro-IX	O
survey	O
,	O
BIRD	O
is	O
the	O
most	O
used	O
route	O
server	O
amongst	O
European	O
Internet	B-Protocol
exchanges	I-Protocol
.	O
</s>
<s>
In	O
2010	O
,	O
CZ.NIC	B-Protocol
,	O
the	O
current	O
sponsor	O
of	O
BIRD	O
development	O
,	O
received	O
the	O
LINX	O
Conspicuous	O
Contribution	O
Award	O
for	O
contribution	O
of	O
BIRD	O
to	O
the	O
advancement	O
in	O
route	O
server	O
technology	O
.	O
</s>
<s>
BIRD	O
implements	O
an	O
internal	O
routing	B-Protocol
table	O
to	O
which	O
the	O
supported	O
protocols	O
connect	O
.	O
</s>
<s>
Most	O
of	O
these	O
protocols	O
import	O
network	O
routes	O
to	O
this	O
internal	O
routing	B-Protocol
table	O
and	O
also	O
export	O
network	O
routes	O
from	O
this	O
internal	O
routing	B-Protocol
table	O
to	O
the	O
given	O
protocol	O
.	O
</s>
<s>
This	O
way	O
information	O
about	O
network	O
routes	O
is	O
exchanged	O
among	O
different	O
routing	B-Protocol
protocols	O
.	O
</s>
<s>
Using	O
the	O
kernel	O
protocol	O
this	O
internal	O
routing	B-Protocol
table	O
may	O
be	O
connected	O
to	O
the	O
actual	O
kernel	O
routing	B-Protocol
table	O
.	O
</s>
<s>
This	O
allows	O
BIRD	O
to	O
export	O
network	O
routes	O
from	O
its	O
internal	O
routing	B-Protocol
table	O
to	O
the	O
kernel	O
routing	B-Protocol
table	O
and	O
optionally	O
also	O
learn	O
about	O
network	O
routes	O
from	O
the	O
kernel	O
routing	B-Protocol
table	O
(	O
created	O
externally	O
by	O
the	O
administrator	O
or	O
by	O
other	O
means	O
)	O
and	O
import	O
these	O
routes	O
into	O
its	O
internal	O
routing	B-Protocol
table	O
.	O
</s>
<s>
Filters	O
may	O
be	O
used	O
to	O
control	O
what	O
network	O
routes	O
are	O
imported	O
into	O
the	O
internal	O
routing	B-Protocol
table	O
or	O
exported	O
to	O
the	O
given	O
protocol	O
.	O
</s>
<s>
BIRD	O
also	O
supports	O
multiple	O
internal	O
routing	B-Protocol
tables	O
and	O
multiple	O
instances	O
of	O
supported	O
protocol	O
types	O
.	O
</s>
<s>
Protocols	O
may	O
be	O
connected	O
to	O
different	O
internal	O
routing	B-Protocol
tables	O
,	O
these	O
internal	O
routing	B-Protocol
tables	O
may	O
exchange	O
information	O
about	O
network	O
routes	O
they	O
contain	O
(	O
controlled	O
by	O
filters	O
)	O
and	O
each	O
of	O
these	O
internal	O
routing	B-Protocol
tables	O
may	O
be	O
connected	O
to	O
a	O
different	O
kernel	O
routing	B-Protocol
table	O
thus	O
allowing	O
for	O
policy	O
routing	B-Protocol
.	O
</s>
<s>
BIRD	O
changes	O
to	O
the	O
new	O
configuration	O
without	O
the	O
need	O
to	O
restart	O
the	O
daemon	B-Operating_System
itself	O
and	O
restarts	O
reconfigured	O
protocols	O
only	O
if	O
necessary	O
.	O
</s>
