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About SCTP
Bersifat Connection-oriented
Merupakan inti dari sigtrans
Menyediakan layanan lapisan transport over IP Merupakan suatu layer yang terletak antara layer user
adaptation dan layer IP di dalam protokol Sigtran.
Layer ini dirancang untuk menyediakan aplikasi
protokol transmisi
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SCTP User Application
SCTP Transport Service
IP Network Service
Asso
ciationstar
upand
takedown
Sequence dilivery within
stream
User Data Fragmentation
Acknowledgement and
Congestion Avoidance
Chunk Bundling
Packetv Validation
Path Management
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Sekilas Proses Aliran Data Dalam
Protokol SCTP
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Header
MAC Add IP Add SCTP Packet Header
Source Dest Source Dest S.Port D. Port Tag CRC Payload
Chunk Chunk
Type Length TSN SI SSN Data Type Length TSN SI SSN Data
SCTP Data Chunks
Format of an SCTP Datagram
Reference : RFC 2960
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SCTP Control Chunk
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SCTP Paket Chunk
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Chunk Types
ID Value Chunk Type ----- ---------- 0 - Payload Data (DATA) 1 - Initiation (INIT) 2 - Initiation Acknowledgement (INIT ACK) 3- Selective Acknowledgement (SACK) 4 - Heartbeat Request (HEARTBEAT) 5 - Heartbeat Acknowledgement (HEARTBEAT ACK) 6 -Abort (ABORT) 7 - Shutdown (SHUTDOWN) 8 - Shutdown Acknowledgement (SHUTDOWN ACK) 9 - Operation Error (ERROR) 10- State Cookie (COOKIE ECHO) 11 - Cookie Acknowledgement (COOKIE ACK) 12 - Reserved for Explicit Congestion Notification Echo (ECNE)13 - Reserved for Congestion Window Reduced (CWR) 14 - Shutdown Complete (SHUTDOWN COMPLETE)
15 to 62 - reserved by IETF
63 - IETF-defined Chunk Extensions
64 to 126 - reserved by IETF
127 - IETF-defined Chunk Extensions
128 to 190 - reserved by IETF
191 - IETF-defined Chunk Extensions
192 to 254 - reserved by IETF 255 - IETF-defined Chunk Extensions
00 - Stop processing this SCTP packet and discard it, do not process
any further chunks within it.
01 - Stop processing this SCTP packet and discard it, do not process
any further chunks within it, and report the unrecognized
parameter in an 'Unrecognized Parameter Type' (in either an
ERROR or in the INIT ACK).
10 - Skip this chunk and continue processing.
11 - Skip this chunk and continue processing, but report in an ERROR
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Chunk flag:
Chunk Length
Chunk Value: variable length
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SCTP Chunk Definitions
A. Initiation (INIT)
This chunk is used to initiate a SCTP association between
two endpoints. The format of the INIT chunk is shown
below:
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B. Initiation Acknowledgement (INIT ACK)
The INIT ACK chunk is used to acknowledge
the initiation of an SCTP association. The
parameter part of INIT ACK is formatted
similarly to the INIT chunk. It uses two extra
variable parameters: The State Cookie and
the Unrecognized Parameter: The format ofthe INIT ACK chunk is shown below:
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Cookie
When sending an INIT ACK as a response toan INIT chunk, the sender of INIT ACK creates aState Cookie and sends it in the State Cookie
parameter of the INIT ACK. Inside this StateCookie, the sender should include a MAC (see[RFC2104] for an example), a time stamp onwhen the State Cookie is created, and the
lifespan of the State Cookie, along with all theinformation necessary for it to establish theassociation.
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Cookie Echo (COOKIE ECHO)
This chunk is used only during the initialization
of an association. It is sent by the initiator of
an association to its peer to complete the
initialization process. This chunk MUST
precede any DATA chunk sent within the
association, but MAY be bundled with one or
more DATA chunks in the same packet.
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Cookie Acknowledgement (COOKIE
ACK)
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INIT : INIT (Initiation) adalah chunk pertama yang dikirim oleh connecting host, INIT digunakan untukmemulai hub baru dgn host tujuan
4-Way Handshake
INIT-ACK : Respon ACK untuk INIT (Initiation) yang pertama dikirim oleh connecting host
COOKIE-ECHO : Dikirimkan oleh inisiator untuk melengkapi proses handshake, Cookie-Echo ini harumengawali semua data tap bisa juga dikirimkan berbarengan pada kiriman pertama