SCTP Technical Tutorial

7/18/2019 SCTP Technical Tutorial

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Technical Tutorial Stream Control Transmission Protocol Page 1

John RumseySenior Systems Engineer

LongReach Networks

LongReach Technical Tutorial


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Stream Control Transmission Protocol

Net !eneration NetworksTCP Transmission Control Protocol

SCTP Stream Control Transmission Protocol

"ser #$a%tation Layers &or SCTP

SCTP Packets

Esta'lishing the Connection (#ssociation)

*ata Transmission

Closing the Connection (#ssociation)

+ultihoming ,%eration

Congestion Control

Security -ssues


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Technical Tutorial Stream Control Transmission Protocol Page .

-P Network

Net !eneration Networks

So&tswitch or

+e$ia !ateway Controller

PB

X

PB

X

P

B

X

P

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X

P

B

X

P/0Sig

nallin

g P/0Signalling

+e$ia !ateway

Control Protocol

+e$ia

!ateway

+e$ia

!ateway

Legacy -S*N

Su'scri'er

Legacy -S*N

Su'scri'er


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Technical Tutorial Stream Control Transmission Protocol Page

-P Network

So&tswitch or


P/0Sig

nallin

g P/0Signalling

+e$ia !ateway

Control ProtocolLegacy -S*N

Su'scri'er

Legacy -S*N

Su'scri'er

PB

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P

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P

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+e$ia

!ateway

+e$ia

!ateway



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-P Network

So&tswitch or


P/0Sig

nallin

g P/0Signalling

+e$ia !ateway


Su'scri'er

Legacy -S*N

Su'scri'er

PB

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+e$ia

!ateway

+e$ia

!ateway



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-P Network

So&tswitch or


P/0Sig

nallin

g P/0Signalling

+e$ia !ateway


Su'scri'er

Legacy -S*N

Su'scri'er

4oice Connection PBX

PB

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+e$ia

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+e$ia

!ateway



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So&tswitch or+e$ia !ateway

Controller

66 P/0 Signalling 7 RTP or "*P or TCP 7 -P 66

4oice7RTP7-P

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8ow are Ser9ices are carrie$ o9er -P

+e$ia!ateway

4oice is carrie$ o9er -P using :Real Time Protocol; 'ut how is

signalling carrie$6


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trans%ort o& message oriente$ a%%lications o9er -P

Su%%orts the goo$ as%ects o& TCP an$ &ies the 'a$ as%ects o& TCP





Controller

Signalling !ateway

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+e$ia!ateway

SCTP

SCTP %ro9i$es the 'ackhauling o& signalling messages 'etween a

Signalling !ateway an$ a +e$ia !ateway Controller> o9er an -P

network




Controller


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+e$ia!ateway

SCTP

Su%%orts multi%le signalling streams o9er a

single SCTP connection (association)




Controller


Signalling !ateway

SCTP

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+e$ia!ateway

"# 7

"ser #$a%tation Layer


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"ser #$a%tation Layers &or SCTP-"#7SCTP

The trans%ort o& -S*N DB21 user messages o9er -P

*"#7SCTP

The trans%ort o& *#SS7*PNSS messages o9er -P

4"#7SCTP

The trans%ort o& 42 messages o9er -P

+TP27SCTP

The trans%ort o& Signalling System 5 +essage Trans&er Part 2 (SS5 +TP2) user

signalling messages o9er -P

+TP.7SCTP

The trans%ort o& any SS5 +TP. = "ser signalling (eg> -S"P an$ SCCP messages)

o9er -P

S"#7SCTP

The trans%ort o& any Signalling Connection Control Part = "ser signalling o9er -P


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SCTP Stream

SCTP "ser

#%%lication

-P NetworkSer9ice

SCTP

Trans%ort

Ser9ice

SCTP "ser

#%%lication

-P NetworkSer9ice

SCTP

Trans%ort

Ser9ice

SCTP No$e # SCTP No$e /

-P Network Trans%ort

Same layer as TCP

an$ "*P a%%lications

Same layer as

TCP an$ "*P


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SCTP Packets

Source

Port

*estination

Port

4eri&ication

Tag

Checksum

Ty%e

Length

4alue

SCTP 8ea$er

@lags

Chunk 1Chunk N

Ty%e

Length

4alue

@lags

2 2N 2 1 1N 2 1 1

#n SCTP %acket &orms the %ayloa$ o& an -P %acket

#n SCTP %acket consists o& a 12 'yte common hea$er

an$ one or more :Chunks;


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SCTP 8ea$er

Source

Port

*estination

Port

4eri&ication

Tag

Checksum

SCTP 8ea$er

2 2

Source Port G *estination Port="ses same %ort conce%t as TCP an$ "*P

4eri&ication Tag

=Echange$ 'etween en$%oints at startu%=2 %er #ssociation=To 4ali$ate the sen$er

Checksum

=Protecte$ 'y .2 'it checksum (CRC.2algorithm)


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Technical Tutorial Stream Control Transmission Protocol Page 1 along with the $eri9e$

message authentication co$e (+#C)The C,,H-E is sent to the sen$er o& the -N-T Chunk in an -N-T

#CH Chunk

En$%oint / remains in the CL,SE* ST#TE


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-nitiation #cknowle$gement (-N-T #CH) Chunk

Ty%e I 2 Chunk @lags

Num'er o& -n'oun$ Streams

Chunk Length

-nitiate Tag

#$9ertise$ Recei9er Fin$ow Cre$it (arwn$)

,%tional74aria'le=Length Parameters

-nitial Transmission Se?uence Num'er (TSN)

Num'er o& ,ut'oun$ Streams

State Cookie Parameter (+an$atory Parameter)Ty%e I 5 Parameter Length

Parameter 4alue

E t 'li hi th # i ti


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-N-T chunk

-N-T=#CH chunk (contains C,,H-E)

C,,H-E=EC8, chunk

CL,SE* ST#TE CL,SE* ST#TE

SCTP

En$%oint #

SCTP

En$%oint /

Esta'lishing the #ssociation

C,,H-E=F#-T

C,,H-E=EC8,E*

En$%oint # takes the C,,H-E &rom the -N-T=#CH chunk> %laces it in aC,,H-E EC8, chunk an$ returns it to En$%oint /

En$%oint # enters the C,,H-E=EC8,E* ST#TE


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Cookie Echo (C,,H-E EC8,) Chunk

Ty%e I 1 LengthChunk @lags

Cookie

E t 'li hi th # i ti


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the Congestion Control Fin$ow will

'e reset> an$ the Slow Start

Threshol$ may 'e lowere$


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