<s>
The	O
Stream	B-Protocol
Control	I-Protocol
Transmission	I-Protocol
Protocol	I-Protocol
(	O
SCTP	B-Protocol
)	O
has	O
a	O
simpler	O
basic	O
packet	O
structure	O
than	O
TCP	B-Protocol
.	O
</s>
<s>
The	O
data	O
chunks	B-General_Concept
,	O
which	O
form	O
the	O
remaining	O
portion	O
of	O
the	O
packet	O
.	O
</s>
<s>
In	O
the	O
diagram	O
,	O
the	O
first	O
chunk	B-General_Concept
is	O
highlighted	O
in	O
green	O
and	O
the	O
last	O
of	O
N	O
chunks	B-General_Concept
(	O
ChunkN	O
)	O
is	O
highlighted	O
in	O
red	O
.	O
</s>
<s>
All	O
SCTP	B-Protocol
packets	O
require	O
the	O
common	O
header	O
section	O
(	O
shown	O
with	O
a	O
blue	O
background	O
)	O
.	O
</s>
<s>
Checksum	O
SCTP	B-Protocol
's	O
original	O
design	O
catered	O
for	O
Adler-32	B-Algorithm
;	O
but	O
RFC	O
3309	O
changed	O
the	O
protocol	O
to	O
use	O
the	O
CRC32c	O
algorithm	O
.	O
</s>
<s>
Each	O
SCTP	B-Protocol
packet	O
consists	O
,	O
in	O
addition	O
to	O
the	O
common	O
header	O
,	O
of	O
chunks	B-General_Concept
.	O
</s>
<s>
Each	O
chunk	B-General_Concept
has	O
a	O
common	O
format	O
,	O
but	O
the	O
contents	O
can	O
vary	O
.	O
</s>
<s>
The	O
green	O
bytes	O
in	O
the	O
diagram	O
above	O
signify	O
one	O
chunk	B-General_Concept
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
An	O
8-bit	O
value	O
predefined	O
by	O
the	O
IETF	O
to	O
identify	O
the	O
contents	O
of	O
the	O
chunk	B-General_Concept
value	O
field	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
Eight	O
flag-bits	O
whose	O
definition	O
varies	O
with	O
the	O
chunk	B-General_Concept
type	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
A	O
16-bit	O
unsigned	O
value	O
specifying	O
the	O
total	O
length	O
of	O
the	O
chunk	B-General_Concept
in	O
bytes	O
(	O
excludes	O
any	O
padding	B-Application
)	O
that	O
includes	O
chunk	B-General_Concept
type	O
,	O
flags	O
,	O
length	O
,	O
and	O
value	O
fields	O
.	O
</s>
<s>
Chunk	B-General_Concept
data	O
General-purpose	O
data	O
field	O
whose	O
definition	O
varies	O
with	O
the	O
chunk	B-General_Concept
type	O
.	O
</s>
<s>
If	O
the	O
chunk	B-General_Concept
length	O
does	O
not	O
equate	O
to	O
a	O
multiple	O
of	O
4bytes	O
,	O
then	O
the	O
protocol	O
implicitly	O
pads	O
the	O
chunk	B-General_Concept
with	O
trailing	O
zeros	O
.	O
</s>
<s>
Additionally	O
,	O
each	O
chunk	B-General_Concept
type	O
may	O
define	O
a	O
set	O
of	O
parameters	O
which	O
it	O
includes	O
inside	O
the	O
chunk	B-General_Concept
value	O
field	O
(	O
and	O
,	O
consequently	O
,	O
their	O
length	O
in	O
the	O
chunk	B-General_Concept
length	O
)	O
.	O
</s>
<s>
For	O
optional/variable	O
-length	O
parameters	O
,	O
the	O
parameter	O
type	O
,	O
parameter	O
length	O
,	O
and	O
parameter	O
value	O
fields	O
all	O
behave	O
just	O
like	O
their	O
chunk	B-General_Concept
counterparts	O
.	O
</s>
<s>
RFC	O
2960	O
defines	O
the	O
following	O
list	O
of	O
chunk	B-General_Concept
types	O
.	O
</s>
<s>
Following	O
this	O
table	O
each	O
chunk	B-General_Concept
and	O
its	O
parameters	O
are	O
defined	O
.	O
</s>
<s>
gray	O
:	O
chunk	B-General_Concept
fields	O
,	O
</s>
<s>
Value	O
Abbreviation	O
Description	O
0	O
DATA	O
Payload	O
data	O
1	O
INIT	O
Initiation	O
2	O
INIT	O
ACK	O
Initiation	O
acknowledgement	O
3	O
SACK	O
Selective	O
acknowledgement	O
4	O
HEARTBEAT	O
Heartbeat	O
request	O
5	O
HEARTBEAT	O
ACK	O
Heartbeat	O
acknowledgement	O
6	O
ABORT	O
Abort	O
7	O
SHUTDOWN	O
Shutdown	O
8	O
SHUTDOWN	O
ACK	O
Shutdown	O
acknowledgement	O
9	O
ERROR	O
Operation	O
error	O
10	O
COOKIE	O
ECHO	O
State	O
cookie	O
11	O
COOKIE	O
ACK	O
Cookie	O
acknowledgement	O
12	O
ECNE	O
Explicit	O
congestion	O
notification	O
echo	O
(	O
reserved	O
)	O
13	O
CWR	O
Congestion	O
window	O
reduced	O
(	O
reserved	O
)	O
14	O
SHUTDOWN	O
COMPLETE	O
Shutdown	O
complete	O
15	O
AUTH	O
Authentication	O
chunk	B-General_Concept
16	O
–	O
62	O
N/A	O
Reserved	O
by	O
IETF	O
63	O
IETF-defined	O
chunk	B-General_Concept
extensions	O
64	O
I-DATA	O
Payload	O
data	O
supporting	O
packet	O
interleaving	O
65	O
–	O
126	O
N/A	O
Reserved	O
by	O
IETF	O
127	O
IETF-defined	O
chunk	B-General_Concept
extensions	O
128	O
ASCONF-ACK	O
Address	O
configuration	O
change	O
acknowledgement	O
129	O
N/A	O
UnassignedSee	O
https://www.iana.org/assignments/sctp-parameters/sctp-parameters.xhtml	O
;	O
possibly	O
used	O
in	O
an	O
internet	O
draft	O
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
always	O
0	O
for	O
payload	O
data	O
(	O
DATA	O
)	O
.	O
</s>
<s>
I	O
—	O
SACK	O
chunk	B-General_Concept
should	O
be	O
sent	O
back	O
without	O
delay	O
.	O
</s>
<s>
U	O
—	O
If	O
set	O
,	O
this	O
indicates	O
that	O
this	O
data	O
is	O
an	O
unordered	O
chunk	B-General_Concept
and	O
the	O
stream	O
sequence	B-Protocol
number	I-Protocol
is	O
invalid	O
.	O
</s>
<s>
If	O
an	O
unordered	O
chunk	B-General_Concept
is	O
fragmented	O
,	O
then	O
each	O
fragment	O
has	O
this	O
flag	O
set	O
.	O
</s>
<s>
An	O
unfragmented	O
chunk	B-General_Concept
has	O
this	O
flag	O
set	O
.	O
</s>
<s>
An	O
unfragmented	O
chunk	B-General_Concept
has	O
this	O
flag	O
set	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
The	O
chunk	B-General_Concept
length	O
has	O
a	O
minimum	O
value	O
of	O
17	O
as	O
data	O
of	O
size	O
less	O
than	O
one	O
byte	O
is	O
not	O
allowed	O
.	O
</s>
<s>
Transmission	O
sequence	B-Protocol
number	I-Protocol
(	O
TSN	O
)	O
The	O
sequence	B-Protocol
number	I-Protocol
for	O
the	O
entire	O
DATA	O
stream	O
(	O
used	O
in	O
fragmentation	O
for	O
reassembly	O
)	O
.	O
</s>
<s>
Stream	O
identifier	O
Identifier	O
of	O
the	O
stream	O
that	O
this	O
data	O
chunk	B-General_Concept
belongs	O
to	O
.	O
</s>
<s>
Stream	O
sequence	B-Protocol
number	I-Protocol
Identifier	O
of	O
the	O
sequence	B-Protocol
number	I-Protocol
for	O
the	O
message	O
in	O
this	O
stream	O
.	O
</s>
<s>
SCTP	B-Protocol
makes	O
no	O
use	O
of	O
this	O
or	O
modification	O
of	O
it	O
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
always	O
1	O
for	O
initiation	O
(	O
INIT	O
)	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
are	O
currently	O
no	O
flags	O
used	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
This	O
is	O
the	O
chunk	B-General_Concept
length	O
which	O
has	O
a	O
minimum	O
value	O
of	O
20	O
when	O
chunk	B-General_Concept
value	O
is	O
empty	O
and	O
no	O
optional	O
parameters	O
are	O
used	O
.	O
</s>
<s>
Initiate	O
tag	O
Unsigned	O
32-bit	O
number	O
that	O
is	O
used	O
in	O
every	O
SCTP	B-Protocol
packet	O
in	O
the	O
verification	O
tag	O
within	O
the	O
common	O
header	O
.	O
</s>
<s>
Initial	O
TSN	O
Initial	O
transmission	O
sequence	B-Protocol
number	I-Protocol
to	O
be	O
used	O
and	O
may	O
be	O
any	O
value	O
.	O
</s>
<s>
Parameter	O
type	O
=	O
5	O
This	O
parameter	O
lists	O
all	O
the	O
IPv4	B-Protocol
addresses	O
used	O
at	O
the	O
sending	O
endpoint	O
.	O
</s>
<s>
Parameter	O
type	O
=	O
6	O
This	O
parameter	O
lists	O
all	O
the	O
IPv6	B-Protocol
addresses	O
used	O
at	O
the	O
sending	O
endpoint	O
.	O
</s>
<s>
Actual	O
resolution	O
of	O
this	O
name	O
is	O
outside	O
the	O
scope	O
of	O
SCTP	B-Protocol
.	O
</s>
<s>
Parameter	O
type	O
=	O
12	O
This	O
parameter	O
lists	O
the	O
address	O
types	O
the	O
sender	O
supports	O
(	O
e.g.	O
,	O
IPv4	B-Protocol
=	O
5	O
,	O
IPv6	B-Protocol
=	O
6	O
,	O
hostname	O
=	O
11	O
)	O
.	O
</s>
<s>
The	O
INIT	O
ACK	O
chunk	B-General_Concept
replicates	O
the	O
INIT	O
chunk	B-General_Concept
except	O
the	O
chunk	B-General_Concept
type	O
is	O
always	O
2	O
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
Always	O
3	O
for	O
selective	O
acknowledgment	O
(	O
SACK	O
)	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
are	O
currently	O
no	O
flags	O
used	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
This	O
is	O
the	O
chunk	B-General_Concept
length	O
,	O
which	O
has	O
a	O
minimum	O
value	O
of	O
16	O
when	O
no	O
gaps	O
or	O
duplicates	O
are	O
sent	O
.	O
</s>
<s>
Cumulative	O
TSN	O
ACK	O
Acknowledges	O
all	O
sequence	B-Protocol
numbers	I-Protocol
up	O
to	O
and	O
including	O
this	O
number	O
.	O
</s>
<s>
Chunks	B-General_Concept
with	O
TSNs	O
above	O
this	O
number	O
have	O
not	O
been	O
received	O
yet	O
–	O
except	O
those	O
included	O
in	O
the	O
optional	O
gap	O
ACK	O
blocks	O
(	O
see	O
below	O
)	O
.	O
</s>
<s>
pairs	O
of	O
start	O
and	O
end	O
TSNs	O
)	O
included	O
in	O
this	O
chunk	B-General_Concept
.	O
</s>
<s>
Number	O
of	O
duplicate	O
TSNs	O
Indicates	O
the	O
number	O
of	O
duplicate	O
TSNs	O
reported	O
in	O
this	O
chunk	B-General_Concept
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
For	O
heartbeat	O
(	O
HEARTBEAT	O
)	O
,	O
this	O
value	O
is	O
always	O
4	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
are	O
currently	O
no	O
flags	O
used	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
This	O
is	O
the	O
chunk	B-General_Concept
length	O
which	O
has	O
a	O
minimum	O
value	O
of	O
8	O
with	O
no	O
parameter	O
value	O
added	O
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
For	O
heartbeat	O
acknowledgement	O
(	O
HEARTBEAT	O
ACK	O
)	O
,	O
this	O
value	O
is	O
always	O
5	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
are	O
currently	O
no	O
flags	O
used	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
This	O
is	O
the	O
chunk	B-General_Concept
length	O
,	O
which	O
has	O
a	O
minimum	O
value	O
of	O
8	O
with	O
no	O
parameter	O
value	O
added	O
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
always	O
6	O
for	O
abort	O
(	O
ABORT	O
)	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
is	O
currently	O
only	O
one	O
flag	O
used	O
:	O
</s>
<s>
Chunk	B-General_Concept
length	O
This	O
is	O
the	O
chunk	B-General_Concept
length	O
,	O
which	O
has	O
a	O
minimum	O
value	O
of	O
4	O
with	O
no	O
error	O
causes	O
given	O
.	O
</s>
<s>
Optional	O
parameters	O
(	O
the	O
error	O
causes	O
)	O
are	O
defined	O
in	O
the	O
ERROR	O
chunk	B-General_Concept
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
For	O
shutdown	O
(	O
SHUTDOWN	O
)	O
,	O
this	O
value	O
is	O
always	O
7	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
are	O
currently	O
no	O
flags	O
used	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
This	O
is	O
the	O
chunk	B-General_Concept
length	O
,	O
which	O
has	O
a	O
fixed	O
length	O
of	O
8	O
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
For	O
shutdown	O
acknowledgement	O
(	O
SHUTDOWN	O
ACK	O
)	O
,	O
this	O
value	O
is	O
always	O
8	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
are	O
currently	O
no	O
flags	O
used	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
This	O
is	O
the	O
chunk	B-General_Concept
length	O
,	O
which	O
has	O
a	O
fixed	O
length	O
of	O
4	O
.	O
</s>
<s>
+	O
Bits	O
0	O
–	O
7	O
8	O
–	O
15	O
16	O
–	O
31	O
0	O
Chunk	B-General_Concept
type	O
=	O
9	O
Chunk	B-General_Concept
flags	O
Chunk	B-General_Concept
length	O
32	O
Parameter	O
type	O
=	O
1	O
Parameter	O
length	O
=	O
8	O
64	O
Stream	O
identifier	O
Zeros	O
(	O
reserved	O
)	O
96	O
Parameter	O
type	O
=	O
2	O
Parameter	O
length	O
128	O
Number	O
of	O
missing	O
parameters	O
=	O
N	O
160	O
Missing	O
parameter	O
type	O
#1	O
Missing	O
parameter	O
type	O
#2	O
192	O
...	O
</s>
<s>
Chunk	B-General_Concept
type	O
For	O
error	O
(	O
ERROR	O
)	O
,	O
this	O
value	O
is	O
always	O
9	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
are	O
currently	O
no	O
flags	O
used	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
This	O
is	O
the	O
chunk	B-General_Concept
length	O
,	O
which	O
has	O
a	O
minimum	O
value	O
of	O
8	O
when	O
only	O
one	O
error	O
is	O
sent	O
with	O
no	O
parameter	O
value	O
.	O
</s>
<s>
Parameter	O
type	O
=	O
2	O
This	O
parameter	O
indicates	O
that	O
the	O
sender	O
received	O
an	O
INIT	O
or	O
INIT	O
ACK	O
chunk	B-General_Concept
with	O
missing	O
mandatory	O
parameters	O
.	O
</s>
<s>
Parameter	O
type	O
=	O
4	O
This	O
parameter	O
indicates	O
the	O
sender	O
is	O
out	O
of	O
resources	O
;	O
this	O
usually	O
accompanies	O
an	O
ABORT	O
chunk	B-General_Concept
.	O
</s>
<s>
Parameter	O
type	O
=	O
5	O
This	O
parameter	O
identifies	O
an	O
address	O
that	O
the	O
sender	O
could	O
not	O
resolve	O
(	O
possibly	O
because	O
it	O
does	O
not	O
support	O
the	O
address	O
type	O
)	O
;	O
this	O
usually	O
accompanies	O
an	O
ABORT	O
chunk	B-General_Concept
.	O
</s>
<s>
Parameter	O
type	O
=	O
6	O
This	O
parameter	O
identifies	O
an	O
unrecognized	O
chunk	B-General_Concept
when	O
the	O
chunk	B-General_Concept
type	O
's	O
most-significant	O
bits	O
are	O
01	O
or	O
11	O
.	O
</s>
<s>
Parameter	O
type	O
=	O
7	O
This	O
parameter	O
identifies	O
a	O
mandatory	O
parameter	O
in	O
an	O
INIT	O
or	O
INIT	O
ACK	O
chunk	B-General_Concept
has	O
an	O
invalid	O
value	O
.	O
</s>
<s>
Parameter	O
type	O
=	O
8	O
This	O
parameter	O
is	O
directed	O
to	O
the	O
originator	O
of	O
an	O
INIT	O
ACK	O
chunk	B-General_Concept
that	O
contained	O
an	O
unrecognized	O
parameter	O
.	O
</s>
<s>
Parameter	O
type	O
=	O
9	O
This	O
parameter	O
indicates	O
a	O
DATA	O
chunk	B-General_Concept
contained	O
no	O
user	O
data	O
;	O
this	O
usually	O
accompanies	O
an	O
ABORT	O
chunk	B-General_Concept
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
always	O
10	O
for	O
cookie	O
echo	O
(	O
COOKIE	O
ECHO	O
)	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
are	O
currently	O
no	O
flags	O
used	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
This	O
is	O
the	O
chunk	B-General_Concept
length	O
.	O
</s>
<s>
Chunk	B-General_Concept
value	O
Contains	O
the	O
cookie	O
data	O
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
For	O
cookie	O
acknowledgement	O
(	O
COOKIE	O
ACK	O
)	O
,	O
this	O
value	O
is	O
always	O
11	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
are	O
currently	O
no	O
flags	O
used	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
This	O
is	O
the	O
chunk	B-General_Concept
length	O
and	O
is	O
always	O
4	O
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
For	O
shutdown	O
complete	O
(	O
SHUTDOWN	O
COMPLETE	O
)	O
,	O
this	O
value	O
is	O
always	O
14	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
This	O
is	O
the	O
chunk	B-General_Concept
length	O
,	O
which	O
has	O
a	O
fixed	O
length	O
of	O
4	O
.	O
</s>
<s>
+	O
Bits	O
0	O
–	O
7	O
8	O
–	O
15	O
16	O
–	O
31	O
0	O
Chunk	B-General_Concept
type	O
=	O
15	O
Flags	O
=	O
0	O
Chunk	B-General_Concept
length	O
32	O
Shared	O
key	O
identifier	O
HMAC	B-Algorithm
identifier	O
64	O
HMAC	B-Algorithm
...	O
</s>
<s>
Chunk	B-General_Concept
type	O
For	O
the	O
authentication	O
chunk	B-General_Concept
(	O
AUTH	O
)	O
,	O
this	O
value	O
is	O
always	O
15	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
are	O
currently	O
no	O
flags	O
used	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
Length	O
of	O
the	O
HMAC	B-Algorithm
+	O
8	O
.	O
</s>
<s>
HMAC	B-Algorithm
identifier	O
identifies	O
the	O
type	O
of	O
HMAC	B-Algorithm
used	O
.	O
</s>
<s>
HMAC	B-Algorithm
HMAC	B-Algorithm
value	I-Algorithm
.	O
</s>
<s>
The	O
SCTP	B-Protocol
protocol	O
takes	O
care	O
of	O
padding	B-Application
to	O
a	O
4-byte	O
boundary	O
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
always	O
128	O
for	O
the	O
address	O
reconfiguration	O
acknowledgement	O
chunk	B-General_Concept
(	O
ASCONF-ACK	O
)	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
are	O
currently	O
no	O
flags	O
used	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
Depends	O
on	O
the	O
number	O
and	O
length	O
of	O
ASCONF	O
parameter	O
responses	O
included	O
.	O
</s>
<s>
Sequence	B-Protocol
number	I-Protocol
The	O
sequence	B-Protocol
number	I-Protocol
of	O
the	O
ASCONF	O
packet	O
being	O
acknowledged	O
.	O
</s>
<s>
+	O
Bits	O
0	O
–	O
7	O
8	O
–	O
15	O
16	O
–	O
31	O
0	O
Chunk	B-General_Concept
type	O
=	O
130	O
Chunk	B-General_Concept
flags	O
Chunk	B-General_Concept
length	O
32	O
Re-configuration	O
parameter	O
1	O
...	O
...	O
Re-configuration	O
parameter	O
2	O
...	O
</s>
<s>
Chunk	B-General_Concept
type	O
always	O
130	O
for	O
the	O
stream	O
reconfiguration	O
chunk	B-General_Concept
(	O
RE-CONFIG	O
)	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
are	O
currently	O
no	O
flags	O
used	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
Depends	O
on	O
the	O
number	O
and	O
length	O
of	O
re-configuration	O
parameters	O
.	O
</s>
<s>
At	O
most	O
two	O
re-configuration	O
parameters	O
from	O
those	O
mentioned	O
below	O
may	O
appear	O
in	O
this	O
chunk	B-General_Concept
.	O
</s>
<s>
This	O
parameter	O
is	O
used	O
by	O
a	O
sender	O
to	O
inform	O
the	O
receiver	O
that	O
it	O
wishes	O
to	O
reset	O
the	O
sequence	B-Protocol
numbers	I-Protocol
(	O
or	O
message-ids	O
if	O
I-DATA	O
is	O
used	O
)	O
for	O
its	O
outgoing	O
streams	O
.	O
</s>
<s>
Re-configuration	O
request	O
sequence	B-Protocol
number	I-Protocol
Sequence	B-Protocol
number	I-Protocol
of	O
this	O
re-configuration	O
request	O
.	O
</s>
<s>
Re-configuration	O
response	O
sequence	B-Protocol
number	I-Protocol
Sequence	B-Protocol
number	I-Protocol
of	O
the	O
last	O
re-configuration	O
request	O
received	O
.	O
</s>
<s>
This	O
parameter	O
is	O
used	O
by	O
a	O
sender	O
to	O
request	O
that	O
the	O
receiver	O
resets	O
the	O
sequence	B-Protocol
numbers	I-Protocol
(	O
or	O
message-ids	O
if	O
I-DATA	O
is	O
used	O
)	O
for	O
its	O
outgoing	O
streams	O
.	O
</s>
<s>
Re-configuration	O
request	O
sequence	B-Protocol
number	I-Protocol
Sequence	B-Protocol
number	I-Protocol
of	O
this	O
re-configuration	O
request	O
.	O
</s>
<s>
Re-configuration	O
request	O
sequence	B-Protocol
number	I-Protocol
Sequence	B-Protocol
number	I-Protocol
of	O
this	O
re-configuration	O
request	O
.	O
</s>
<s>
Re-configuration	O
response	O
sequence	B-Protocol
number	I-Protocol
Sequence	B-Protocol
number	I-Protocol
of	O
the	O
corresponding	O
re-configuration	O
request	O
.	O
</s>
<s>
Re-configuration	O
request	O
sequence	B-Protocol
number	I-Protocol
Sequence	B-Protocol
number	I-Protocol
of	O
this	O
re-configuration	O
request	O
.	O
</s>
<s>
Re-configuration	O
request	O
sequence	B-Protocol
number	I-Protocol
Sequence	B-Protocol
number	I-Protocol
of	O
this	O
re-configuration	O
request	O
.	O
</s>
<s>
The	O
PAD	O
chunk	B-General_Concept
was	O
introduced	O
to	O
facilitate	O
path	B-Protocol
MTU	I-Protocol
discovery	I-Protocol
,	O
by	O
enabling	O
a	O
sender	O
to	O
arbitrarily	O
increase	O
the	O
size	O
of	O
an	O
SCTP	B-Protocol
packet	O
.	O
</s>
<s>
+	O
Bits	O
0	O
–	O
7	O
8	O
–	O
15	O
16	O
–	O
31	O
0	O
Chunk	B-General_Concept
type	O
=	O
132	O
Chunk	B-General_Concept
flags	O
Chunk	B-General_Concept
length	O
32	O
Padding	B-Application
data	O
...	O
</s>
<s>
Chunk	B-General_Concept
type	O
always	O
132	O
for	O
the	O
padding	B-Application
chunk	B-General_Concept
(	O
PAD	O
)	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
are	O
currently	O
no	O
flags	O
used	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
Depends	O
on	O
the	O
size	O
of	O
padding	B-Application
data	O
.	O
</s>
<s>
Padding	B-Application
data	O
Arbitrary	O
data	O
–	O
will	O
be	O
ignored	O
and	O
unceremoniously	O
discarded	O
by	O
the	O
receiver	O
.	O
</s>
<s>
The	O
I-DATA	O
chunk	B-General_Concept
was	O
introduced	O
to	O
avoid	O
a	O
large	O
message	O
in	O
one	O
stream	O
blocking	O
messages	O
in	O
all	O
other	O
streams	O
from	O
being	O
transmitted	O
:	O
SCTP	B-Protocol
primarily	O
uses	O
the	O
TSN	O
to	O
achieve	O
reliability	O
.	O
</s>
<s>
In	O
some	O
cases	O
,	O
the	O
TSN	O
is	O
also	O
needed	O
to	O
distinguish	O
different	O
DATA	O
chunks	B-General_Concept
.	O
</s>
<s>
When	O
a	O
message	O
is	O
fragmented	O
,	O
the	O
DATA	O
TSN	O
additionally	O
doubles	O
as	O
a	O
fragment	O
sequence	B-Protocol
number	I-Protocol
.	O
</s>
<s>
The	O
I-DATA	O
chunk	B-General_Concept
disentangles	O
the	O
different	O
uses	O
of	O
the	O
TSN	O
in	O
DATA	O
chunks	B-General_Concept
.	O
</s>
<s>
As	O
DATA	O
and	O
I-DATA	O
chunks	B-General_Concept
are	O
not	O
compatible	O
,	O
they	O
may	O
not	O
both	O
be	O
used	O
in	O
the	O
same	O
association	O
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
always	O
64	O
for	O
payload	O
data	O
supporting	O
interleaving	O
(	O
I-DATA	O
)	O
.	O
</s>
<s>
I	O
—	O
SACK	O
chunk	B-General_Concept
should	O
be	O
sent	O
back	O
without	O
delay	O
.	O
</s>
<s>
U	O
—	O
If	O
set	O
,	O
this	O
indicates	O
this	O
data	O
is	O
an	O
unordered	O
chunk	B-General_Concept
.	O
</s>
<s>
If	O
an	O
unordered	O
chunk	B-General_Concept
is	O
fragmented	O
,	O
then	O
each	O
fragment	O
has	O
this	O
flag	O
set	O
.	O
</s>
<s>
An	O
unfragmented	O
chunk	B-General_Concept
has	O
this	O
flag	O
set	O
.	O
</s>
<s>
An	O
unfragmented	O
chunk	B-General_Concept
has	O
this	O
flag	O
set	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
The	O
chunk	B-General_Concept
length	O
has	O
a	O
minimum	O
value	O
of	O
21	O
,	O
as	O
data	O
of	O
size	O
less	O
than	O
one	O
byte	O
is	O
not	O
allowed	O
.	O
</s>
<s>
Transmission	O
sequence	B-Protocol
number	I-Protocol
(	O
TSN	O
)	O
The	O
sequence	B-Protocol
number	I-Protocol
for	O
the	O
entire	O
DATA	O
stream	O
(	O
used	O
for	O
acknowledgement	O
and	O
retransmission	O
)	O
.	O
</s>
<s>
Stream	O
identifier	O
Identifier	O
of	O
the	O
stream	O
that	O
this	O
data	O
chunk	B-General_Concept
belongs	O
to	O
.	O
</s>
<s>
SCTP	B-Protocol
makes	O
no	O
use	O
of	O
this	O
or	O
modification	O
of	O
it	O
.	O
</s>
<s>
Fragment	O
sequence	B-Protocol
number	I-Protocol
Fragment	O
number	O
for	O
fragmented	O
packets	O
.	O
</s>
<s>
If	O
the	O
B	O
flag	O
is	O
set	O
,	O
then	O
the	O
fragment	O
sequence	B-Protocol
number	I-Protocol
is	O
implicitly	O
zero	O
,	O
and	O
the	O
payload	O
protocol	O
identifier	O
occupies	O
the	O
same	O
space	O
instead	O
.	O
</s>
<s>
The	O
FORWARD-TSN	O
chunk	B-General_Concept
was	O
introduced	O
to	O
support	O
selective	O
unreliability	O
:	O
it	O
allows	O
the	O
sender	O
to	O
tell	O
the	O
receiver	O
that	O
it	O
will	O
not	O
retransmit	O
some	O
number	O
of	O
chunks	B-General_Concept
,	O
and	O
requests	O
that	O
the	O
receiver	O
consider	O
all	O
these	O
chunks	B-General_Concept
as	O
received	O
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
always	O
192	O
for	O
the	O
forward	O
TSN	O
chunk	B-General_Concept
(	O
FORWARD-TSN	O
)	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
are	O
currently	O
no	O
flags	O
used	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
Depends	O
on	O
the	O
number	O
of	O
new	O
stream	O
sequence	B-Protocol
numbers	I-Protocol
included	O
.	O
</s>
<s>
New	O
cumulative	O
transmission	O
sequence	B-Protocol
number	I-Protocol
(	O
TSN	O
)	O
The	O
next	O
TSN	O
that	O
the	O
receiver	O
should	O
expect	O
.	O
</s>
<s>
Stream	O
identifier	O
1	O
..	O
N	O
Stream	O
identifiers	O
of	O
streams	O
that	O
were	O
skipped	O
by	O
this	O
chunk	B-General_Concept
.	O
</s>
<s>
Stream	O
sequence	O
1	O
..	O
N	O
New	O
stream	O
sequence	B-Protocol
numbers	I-Protocol
associated	O
with	O
the	O
streams	O
that	O
were	O
skipped	O
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
always	O
193	O
for	O
the	O
address	O
reconfiguration	O
chunk	B-General_Concept
(	O
ASCONF	O
)	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
are	O
currently	O
no	O
flags	O
used	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
Depends	O
on	O
the	O
type	O
of	O
IP	O
address	O
and	O
the	O
number	O
and	O
lengths	O
of	O
ASCONF	O
parameters	O
included	O
.	O
</s>
<s>
Sequence	B-Protocol
number	I-Protocol
The	O
sequence	B-Protocol
number	I-Protocol
of	O
the	O
ASCONF	O
packet	O
.	O
</s>
<s>
Address	O
parameter	O
parameter	O
type	O
:	O
Type	O
of	O
address	O
in	O
the	O
address	O
parameter	O
:	O
5	O
for	O
IPv4	B-Protocol
,	O
6	O
for	O
IPv6	B-Protocol
.	O
</s>
<s>
Address	O
parameter	O
parameter	O
length	O
:	O
Length	O
of	O
the	O
address	O
parameter	O
:	O
8	O
for	O
IPv4	B-Protocol
,	O
20	O
for	O
IPv6	B-Protocol
.	O
</s>
<s>
Address	O
parameter	O
IP	O
address	O
:	O
4	O
bytes	O
for	O
IPv4	B-Protocol
,	O
16	O
bytes	O
for	O
IPv6	B-Protocol
.	O
</s>
<s>
The	O
I-FORWARD-TSN	O
chunk	B-General_Concept
was	O
introduced	O
to	O
be	O
used	O
instead	O
of	O
FORWARD-TSN	O
when	O
I-DATA	O
is	O
used	O
instead	O
of	O
DATA	O
.	O
</s>
<s>
Chunk	B-General_Concept
type	O
always	O
194	O
for	O
the	O
forward	O
TSN	O
chunk	B-General_Concept
with	O
support	O
for	O
interleaving	O
(	O
I-FORWARD-TSN	O
)	O
.	O
</s>
<s>
Chunk	B-General_Concept
flags	O
There	O
are	O
currently	O
no	O
flags	O
used	O
.	O
</s>
<s>
Chunk	B-General_Concept
length	O
Depends	O
on	O
the	O
number	O
of	O
new	O
stream	O
message	O
identifiers	O
included	O
.	O
</s>
<s>
New	O
cumulative	O
transmission	O
sequence	B-Protocol
number	I-Protocol
(	O
TSN	O
)	O
The	O
next	O
TSN	O
that	O
the	O
receiver	O
should	O
expect	O
.	O
</s>
<s>
Stream	O
identifier	O
1	O
..	O
N	O
Stream	O
identifiers	O
of	O
streams	O
that	O
were	O
skipped	O
by	O
this	O
chunk	B-General_Concept
.	O
</s>
