<s>
The	O
Resource	B-Protocol
Reservation	I-Protocol
Protocol	I-Protocol
(	O
RSVP	B-Protocol
)	O
is	O
a	O
transport	B-Architecture
layer	I-Architecture
protocol	O
designed	O
to	O
reserve	O
resources	O
across	O
a	O
network	B-Architecture
using	O
the	O
integrated	O
services	O
model	O
.	O
</s>
<s>
RSVP	B-Protocol
operates	O
over	O
an	O
IPv4	B-Protocol
or	O
IPv6	B-Protocol
and	O
provides	O
receiver-initiated	O
setup	O
of	O
resource	O
reservations	O
for	O
multicast	B-Protocol
or	O
unicast	B-Protocol
data	O
flows	O
.	O
</s>
<s>
It	O
does	O
not	O
transport	O
application	O
data	O
but	O
is	O
similar	O
to	O
a	O
control	O
protocol	O
,	O
like	O
Internet	B-Protocol
Control	I-Protocol
Message	I-Protocol
Protocol	I-Protocol
(	O
ICMP	O
)	O
or	O
Internet	B-Protocol
Group	I-Protocol
Management	I-Protocol
Protocol	I-Protocol
(	O
IGMP	B-Protocol
)	O
.	O
</s>
<s>
RSVP	B-Protocol
is	O
described	O
in	O
.	O
</s>
<s>
RSVP	B-Protocol
can	O
be	O
used	O
by	O
hosts	B-Device
and	O
routers	B-Protocol
to	O
request	O
or	O
deliver	O
specific	O
levels	O
of	O
quality	O
of	O
service	O
(	O
QoS	O
)	O
for	O
application	O
data	B-Architecture
streams	I-Architecture
.	O
</s>
<s>
RSVP	B-Protocol
defines	O
how	O
applications	O
place	O
reservations	O
and	O
how	O
they	O
can	O
relinquish	O
the	O
reserved	O
resources	O
once	O
no	O
longer	O
required	O
.	O
</s>
<s>
RSVP	B-Protocol
operations	O
will	O
generally	O
result	O
in	O
resources	O
being	O
reserved	O
in	O
each	O
node	O
along	O
a	O
path	O
.	O
</s>
<s>
RSVP	B-Protocol
is	O
not	O
a	O
routing	B-Protocol
protocol	I-Protocol
but	O
was	O
designed	O
to	O
interoperate	O
with	O
current	O
and	O
future	O
routing	B-Protocol
protocols	I-Protocol
.	O
</s>
<s>
RSVP	B-Protocol
by	O
itself	O
is	O
rarely	O
deployed	O
in	O
telecommunications	O
networks	O
.	O
</s>
<s>
In	O
2003	O
,	O
development	O
effort	O
was	O
shifted	O
from	O
RSVP	B-Protocol
to	O
RSVP-TE	B-Protocol
for	O
teletraffic	O
engineering	O
.	O
</s>
<s>
Next	O
Steps	O
in	O
Signaling	O
(	O
NSIS	O
)	O
was	O
a	O
proposed	O
replacement	O
for	O
RSVP	B-Protocol
.	O
</s>
<s>
RSVP	B-Protocol
requests	O
resources	O
for	O
simplex	O
flows	O
:	O
a	O
traffic	O
stream	O
in	O
only	O
one	O
direction	O
from	O
sender	O
to	O
one	O
or	O
more	O
receivers	O
.	O
</s>
<s>
RSVP	B-Protocol
is	O
not	O
a	O
routing	B-Protocol
protocol	I-Protocol
but	O
works	O
with	O
current	O
and	O
future	O
routing	B-Protocol
protocols	I-Protocol
.	O
</s>
<s>
RSVP	B-Protocol
is	O
receiver	O
oriented	O
in	O
that	O
the	O
receiver	O
of	O
a	O
data	O
flow	O
initiates	O
and	O
maintains	O
the	O
resource	O
reservation	O
for	O
that	O
flow	O
.	O
</s>
<s>
RSVP	B-Protocol
maintains	O
soft	B-Architecture
state	I-Architecture
(	O
the	O
reservation	O
at	O
each	O
node	O
needs	O
a	O
periodic	O
refresh	O
)	O
of	O
the	O
host	O
and	O
routers	B-Protocol
 '	O
resource	O
reservations	O
,	O
hence	O
supporting	O
dynamic	O
automatic	O
adaptation	O
to	O
network	B-Architecture
changes	O
.	O
</s>
<s>
RSVP	B-Protocol
provides	O
several	O
reservation	O
styles	O
(	O
a	O
set	O
of	O
reservation	O
options	O
)	O
and	O
allows	O
for	O
future	O
styles	O
to	O
be	O
added	O
in	O
protocol	O
revisions	O
to	O
fit	O
varied	O
applications	O
.	O
</s>
<s>
RSVP	B-Protocol
transports	O
and	O
maintains	O
traffic	O
and	O
policy	O
control	O
parameters	O
that	O
are	O
opaque	O
to	O
RSVP	B-Protocol
.	O
</s>
<s>
The	O
basic	O
concepts	O
of	O
RSVP	B-Protocol
were	O
originally	O
proposed	O
in	O
1993	O
.	O
</s>
<s>
RSVP	B-Protocol
is	O
described	O
in	O
a	O
series	O
of	O
RFC	O
documents	O
from	O
the	O
IETF	O
:	O
</s>
<s>
defines	O
the	O
use	O
of	O
RSVP	B-Protocol
with	O
controlled-load	O
RFC	O
2211	O
and	O
guaranteed	O
RFC	O
2212	O
QoS	O
control	O
services	O
.	O
</s>
<s>
Also	O
defines	O
the	O
usage	O
and	O
data	O
format	O
of	O
the	O
data	O
objects	O
(	O
that	O
carry	O
resource	O
reservation	O
information	O
)	O
defined	O
by	O
RSVP	B-Protocol
in	O
RFC	O
2205	O
.	O
</s>
<s>
specifies	O
the	O
network	B-Architecture
element	O
behavior	O
required	O
to	O
deliver	O
Controlled-Load	O
services	O
.	O
</s>
<s>
specifies	O
the	O
network	B-Architecture
element	O
behavior	O
required	O
to	O
deliver	O
guaranteed	O
QoS	O
services	O
.	O
</s>
<s>
describes	O
a	O
proposed	O
extension	O
for	O
supporting	O
generic	O
policy	O
based	O
admission	O
control	O
in	O
RSVP	B-Protocol
.	O
</s>
<s>
,	O
"	O
RSVP-TE	B-Protocol
:	O
Extensions	O
to	O
RSVP	B-Protocol
for	O
LSP	O
Tunnels	O
"	O
(	O
December	O
2001	O
)	O
.	O
</s>
<s>
,	O
"	O
Generalized	O
Multi-Protocol	B-Protocol
Label	I-Protocol
Switching	I-Protocol
(	O
GMPLS	O
)	O
Signaling	O
Resource	O
ReserVation	O
Protocol-Traffic	O
Engineering	O
(	O
RSVP-TE	B-Protocol
)	O
Extensions	O
"	O
(	O
January	O
2003	O
)	O
.	O
</s>
<s>
,	O
"	O
Procedures	O
for	O
Modifying	O
the	O
Resource	B-Protocol
reSerVation	I-Protocol
Protocol	I-Protocol
(	O
RSVP	B-Protocol
)	O
"	O
(	O
October	O
2004	O
)	O
,	O
describes	O
current	O
best	O
practices	O
and	O
specifies	O
procedures	O
for	O
modifying	O
RSVP	B-Protocol
.	O
</s>
<s>
,	O
"	O
A	O
Resource	B-Protocol
Reservation	I-Protocol
Protocol	I-Protocol
(	O
RSVP	B-Protocol
)	O
Extension	O
for	O
the	O
Reduction	O
of	O
Bandwidth	O
of	O
a	O
Reservation	O
Flow	O
"	O
(	O
May	O
2006	O
)	O
,	O
extends	O
RSVP	B-Protocol
to	O
enable	O
the	O
bandwidth	O
of	O
an	O
existing	O
reservation	O
to	O
be	O
reduced	O
instead	O
of	O
tearing	O
down	O
the	O
reservation	O
.	O
</s>
<s>
,	O
"	O
Node-ID	O
Based	O
Resource	B-Protocol
Reservation	I-Protocol
Protocol	I-Protocol
(	O
RSVP	B-Protocol
)	O
Hello	O
:	O
A	O
Clarification	O
Statement	O
"	O
(	O
June	O
2006	O
)	O
.	O
</s>
<s>
The	O
two	O
key	O
concepts	O
of	O
RSVP	B-Protocol
reservation	O
model	O
are	O
flowspec	O
and	O
filterspec	O
.	O
</s>
<s>
RSVP	B-Protocol
reserves	O
resources	O
for	O
a	O
flow	O
.	O
</s>
<s>
In	O
multiprotocol	B-Protocol
label	I-Protocol
switching	I-Protocol
(	O
MPLS	B-Protocol
)	O
a	O
flow	O
is	O
defined	O
as	O
a	O
label	O
switched	O
path	O
(	O
LSP	O
)	O
.	O
</s>
<s>
For	O
each	O
flow	O
,	O
RSVP	B-Protocol
also	O
identifies	O
the	O
particular	O
quality	O
of	O
service	O
(	O
QoS	O
)	O
required	O
by	O
the	O
flow	O
.	O
</s>
<s>
This	O
QoS	O
information	O
is	O
called	O
a	O
flowspec	O
and	O
RSVP	B-Protocol
passes	O
the	O
flowspec	O
from	O
the	O
application	O
to	O
the	O
hosts	B-Device
and	O
routers	B-Protocol
along	O
the	O
path	O
.	O
</s>
<s>
The	O
currently	O
defined	O
RSVP	B-Protocol
reservation	O
styles	O
are	O
:	O
</s>
<s>
An	O
RSVP	B-Protocol
reservation	O
request	O
consists	O
of	O
a	O
flowspec	O
and	O
a	O
filterspec	O
and	O
the	O
pair	O
is	O
called	O
a	O
flowdescriptor	O
.	O
</s>
<s>
The	O
data	O
objects	O
on	O
RSVP	B-Protocol
messages	O
can	O
be	O
transmitted	O
in	O
any	O
order	O
.	O
</s>
<s>
For	O
the	O
complete	O
list	O
of	O
RSVP	B-Protocol
messages	O
and	O
data	O
objects	O
see	O
RFC	O
2205	O
.	O
</s>
<s>
An	O
RSVP	B-Protocol
host	O
that	O
needs	O
to	O
send	O
a	O
data	O
flow	O
with	O
specific	O
QoS	O
will	O
transmit	O
an	O
RSVP	B-Protocol
path	O
message	O
every	O
30	O
seconds	O
that	O
will	O
travel	O
along	O
the	O
unicast	B-Protocol
or	O
multicast	B-Protocol
routes	O
pre-established	O
by	O
the	O
working	O
routing	B-Protocol
protocol	I-Protocol
.	O
</s>
<s>
If	O
the	O
path	O
message	O
arrives	O
at	O
a	O
router	B-Protocol
that	O
does	O
not	O
understand	O
RSVP	B-Protocol
,	O
that	O
router	B-Protocol
forwards	O
the	O
message	O
without	O
interpreting	O
the	O
contents	O
of	O
the	O
message	O
and	O
will	O
not	O
reserve	O
resources	O
for	O
the	O
flow	O
.	O
</s>
<s>
When	O
a	O
router	B-Protocol
receives	O
the	O
RSVP	B-Protocol
resv	O
message	O
it	O
will	O
:	O
</s>
<s>
in	O
the	O
case	O
of	O
a	O
multicast	B-Protocol
flow	O
reservation	O
the	O
reservations	O
requests	O
can	O
be	O
merged	O
)	O
.	O
</s>
<s>
The	O
routers	B-Protocol
then	O
store	O
the	O
nature	O
of	O
the	O
flow	O
and	O
optionally	O
set	O
up	O
policing	O
according	O
to	O
the	O
flowspec	O
for	O
it	O
.	O
</s>
<s>
RSVP	B-Protocol
messages	O
are	O
appended	O
with	O
a	O
message	O
digest	O
created	O
by	O
combining	O
the	O
message	O
contents	O
and	O
a	O
shared	O
key	O
using	O
a	O
message	O
digest	O
algorithm	O
(	O
commonly	O
MD5	B-Algorithm
)	O
.	O
</s>
<s>
Two	O
types	O
of	O
diagnostic	O
messages	O
allow	O
a	O
network	B-Architecture
operator	O
to	O
request	O
the	O
RSVP	B-Protocol
state	O
information	O
on	O
a	O
specific	O
flow	O
.	O
</s>
<s>
An	O
extension	O
to	O
the	O
standard	O
which	O
allows	O
a	O
user	O
to	O
collect	O
information	O
about	O
the	O
RSVP	B-Protocol
state	O
along	O
a	O
path	O
.	O
</s>
