<s>
Constraint-based	B-Protocol
Routing	I-Protocol
Label	I-Protocol
Distribution	I-Protocol
Protocol	I-Protocol
(	O
CR-LDP	B-Protocol
)	O
is	O
a	O
control	O
protocol	O
used	O
in	O
some	O
computer	O
networks	O
.	O
</s>
<s>
As	O
of	O
February	O
2003	O
,	O
the	O
IETF	O
MPLS	B-Protocol
working	O
group	O
deprecated	O
CR-LDP	B-Protocol
and	O
decided	O
to	O
focus	O
purely	O
on	O
RSVP-TE	B-Protocol
.	O
</s>
<s>
It	O
is	O
an	O
extension	O
of	O
the	O
Label	B-Protocol
Distribution	I-Protocol
Protocol	I-Protocol
(	O
LDP	O
)	O
,	O
one	O
of	O
the	O
protocols	O
in	O
the	O
Multiprotocol	B-Protocol
Label	I-Protocol
Switching	I-Protocol
architecture	O
.	O
</s>
<s>
CR-LDP	B-Protocol
contains	O
extensions	O
for	O
LDP	O
to	O
extend	O
its	O
capabilities	O
such	O
as	O
setup	O
paths	O
beyond	O
what	O
is	O
available	O
for	O
the	O
routing	B-Protocol
protocol	O
.	O
</s>
<s>
Constraint-based	O
routing	B-Protocol
(	O
CR	O
)	O
is	O
a	O
mechanism	O
used	O
to	O
meet	O
traffic	O
engineering	O
requirements	O
.	O
</s>
<s>
These	O
requirements	O
are	O
met	O
by	O
extending	O
LDP	O
for	O
support	O
of	O
constraint-based	O
routed	B-Protocol
label	O
switched	O
paths	O
(	O
CR-LSPs	O
)	O
.	O
</s>
<s>
Other	O
uses	O
for	O
CR-LSPs	O
include	O
MPLS-based	O
virtual	B-Application
private	I-Application
networks	I-Application
.	O
</s>
<s>
CR-LDP	B-Protocol
is	O
almost	O
same	O
as	O
basic	O
LDP	O
,	O
in	O
packet	O
structure	O
,	O
but	O
it	O
contains	O
some	O
extra	O
TLVs	O
which	O
basically	O
set	O
up	O
the	O
constraint-based	O
LSP	O
.	O
</s>
