1. Session Initiation Protocol
The department of Information & Communications Engineering
Dong-uk, kim

2. Table of Contents Introduction Transaction Transport Registration
Dialog
Initiating a session
Terminating a session
Headers

3. Introduction

4. Introduction
Many Applications that require the creation and management of a session.
The Session initiation Protocol
Can enabling UA to discover one another
General-purpose tool for creating, modifying and terminating session
Works independently of underlying transport protocols

5. SIP URIs Two URI schemes
Similar to the form of an address:
SIP URI - introduced in RFC 2543
example:
Secure SIP URI - introduced in RFC 3261
example:
Requires TLS over TCP as transport for security

6. SIP URIs (cont’d) Several types of SIP URIs:
Address of Record (AOR) (identifies a user)
example:
Need DNS records to locate SIP Servers for “domain.com”
Fully Qualified Domain Name (FQDN) (identifies a specific device)

7. Functionality User Location User Availability User Capabilities
Determination of the end system to be used for communication
User Availability
Determination of the willingness of the called party to engage in communication
User Capabilities
Determination of the media and media parameters to be used
Session Setup
Establishment of session parameters between parties
Session Management
Transfer, modifying

8. Operation

9. SIP Message structure INVITE sip:bob@biloxi.com SIP/2.0 <CRLF>
Start Line
Via: SIP/2.0/UDP
Call-ID:
From:
To:
CSeq: 1 INVITE
Max-forwards: 70
Content-Type: application/sdp
Content-Length:885
Headers
Blank Line
<CRLF>
v=0
o=xener IN IP
s=hello session
c=IN IP
m=audio 3456 RTP/AVP
Content

10. Request Method INVITE ACK BYE CANCEL OPTIONS REGISTER REFER PUBLISH
Basic
Extention
INVITE
ACK
BYE
CANCEL
OPTIONS
REGISTER
REFER
PUBLISH
SUBSCRIBE
NOTIFY
MESSAGE
INFO
UPDATE

11. Response code 1xx: Provisional
request received, continuing to process the request
2xx: Success
the action was successfully received, understood, and accepted
3xx: Redirection
further action needs to be taken in order to complete the request
4xx: Client Error
the request contains bad syntax or cannot be fulfilled at this server
5xx: Server Error
the server failed to fulfill an apparently valid request
6xx: Global Failure
the request cannot be fulfilled at any server

12. Transaction

13. Transaction A SIP Transaction consists of A single request
Zero or more provisional responses
One or more final responses
i.e.>
An INVITE request
Final response (which is not 2xx response)
The final ACK is part of the transaction

14. Transaction Process

15. INVITE Client Transaction
Timer A
At each retransmit.
T1 = 500ms(default)
Timer B
64 * T1
Timer D
At least 32sec. In unreliable transport
The duration, the server transaction can remain in the Complete state
== at INV. Server trans.
Timer C ?
Managed by TU
Update at recv 101 ~199
Reset to different value
But At least 3 min.
If Fires
CANCLE / treat like 408

16. INVITE Server Transaction
Timer G
At each retransmit.
T1 = 2 * T1
T1 = 500ms(default)
Timer H
64 * T1
== timer B
Timer I

17. Non-INVITE Client Transaction
Non-INVITE transaction do not make use of ACK
Simple req-res interactions

18. Non-INVITE Server Transaction

19. Transport

20. Transport Layer Mandatory UDP & TCP If Message size is larger than
Path MTU – 200
1300 (at unknown path MTU)
Must be sent using an RFC 2914 (such as TCP)

21. Registrations

22. Overview SIP offers a discovery capability
Registration creates bindings in a location service
Associates
AoR ∈ Contact addresses

23. Registration Msg.
The Request-URI names the domain of the location service for which the registration is meant
The to header field containsthe address of record whose registrations is to be created
The From header field contains the address-of-record of the person responsivle foor the registrations The value is the same as the To headerfield unless the request is a third-party registrations
All registrations from a UA should use the same Call-ID header field vbalue for registrations sent to a paricular registar.
The CSeq value guarantees proper ordering of REGISTERrequests. A UA must increment the CSeq value by one for each REGISTER request with the same Call-ID
The Contact header field with zero or more values containing address bindings.
Expire header field indicates how long the UA would like the binding to be vaild. The value is a number indicationg seconds.

24. Discover a Registrar
UA can use three ways to determine the address to which to send registrations
Configuration
With a registrar address
Using AoR
A UA should use the host part of the AoR as the Request- URI and address the request there, using the normal SIP server locations mechanisms
Multicast
Well-known (by all SIP servers) “sip.mcast.net”( )

25. Registrar

26. Dialog

27. Dialog
Represents a Peer to Peer SIP relationship between two user agents
Facilitates sequencing of messages between the UAs and proper routing of requests
A dialog is identified at each UA with a dialog ID which consists of
Call-ID value
A local tag
A remote tag

28. Creating A Dialog

29. Requests within a Dialog

30. Initiating a Session

31. Overview

32. UAC Processing Initial Offer MUST be in either An INVITE
Answer : 2xx Msg.
Final 2xx response
Answer : ACK
Send INVITE Msg.
UAC waits for response for the INVITE
“Expire:”
Transaction returns a timeout
Treat as if “408”

33. UAC Processing 1xx Response Early dialog 3xx Response
Using Contact Addr. Depend on Response Code
4xx ~ 6xx Response
Terminating early dialog

34. UAS Processing “Expires:” in INVITE Request
If fires  487 (Request Terminated)
Progress
Can not answer the invitation immediately
Provisional response
To prevent cancelation
UAS must send a non-100 provisional response at every min.
Redirected
300, 301, 302
“Contact : ”
Rejected
488 response should include a warning header
Why the offer was rejected

35. UAS Processing Accepted The UAS core generates a 2xx response.
INVITE contains offer msg.
2xx response should contain answer

36. Terminating a Session

37. Terminating a Session Each session is Associated with a single dialog
When a BYE is received on a dialog
Any session associated with the dialog should terminated
A UA must not send BYE outside of a dialog

38. UAs Behavior UAC Creates a new non-INVITE client transaction UAS
UAS receiving BYE msg.
Must check if it matches an existing dialog
If not, responses 481 (Call/Transaction does not exists)

39. Headers

40. Summary of SIP headers Header field Where Proxy ACK BYE CAN INV OPT
REG
Compact
Accept R - o m*
2xx
415 c
Accept-Encoding
Accept-Language
Alert-Info ar
180
Allow r

41. Summary of SIP headers(2)
Header field
Where
Proxy
ACK
BYE
CAN
INV
OPT
REG
Compact
Allow
405 - m
Authentication-Info
2xx o
Authorization R
Call-ID c r i
Call-Info ar
Contact
1xx
3xx d
485
Content-Disposition
Content-Encoding e
Content-Language
Content-Length t l

42. Summary of SIP headers(3)
Header field
Where
Proxy
ACK
BYE
CAN
INV
OPT
REG
Compact
Content-Type * - c
CSeq r m
Date a o
Error-Info
Expires
From f
In-Reply-To R
Max-Forwards
amr
Min-Expires
423
MIME-Version
Organization ar
Priority
Proxy-Authenticate
407
401

43. Summary of SIP headers(4)
Header field
Where
Proxy
ACK
BYE
CAN
INV
OPT
REG
Compact
Proxy-Authorization R dr o -
Proxy-Require ar
Record-Route
2xx,18x ma
Reply-To
Require c
Retry-After
404,413,
480,486,
500,503,
600,603
Route
adr
Server r
Subject s
Supported m* k
2xx

44. Summary of SIP headers(5)
Header field
Where
Proxy
ACK
BYE
CAN
INV
OPT
REG
Compact
Timestamp o To
c(1) r m t
Unsupported
420 -
User-Agent
Via R
amr v rc dr
Warning
WWW-Authenticate
401 ar
407
▶ In “where”
R: in requests
r: in responses
2xx, 4xx, etc: response code
c: copied from request to response
▶ In “proxy”
a: can add/concatenate if not present
m: can modify value
d: can delete value
r: must be able to be read (cannot be encrypted)
▶ In methods
c: conditional o: optional
m: mandatory t: should be sent, but can be omitted
m*: should be sent, but can be omitted (mandatory in stream-based transport protocol)

45. IETF WGs Applications Area General Area Internet Area
Operations and Management Area
Real-time Applications and Infrastructure Area
Routing Area
Security Area
Transport Area

46. WGs WG name Activity and Key words avt RTP bliss Interoperability
drinks
Provisioning, orthogonal to ENUM & SPEERMINT
ecrit
Emergency
ENUM
Telephone number mapping
geopriv
Location convey
iptel
Ip telephony with “tel” URI
mediactrl
Media server control
mmusic
SDP
p2psip
P2psip
sigtran
IP, PSTN interworking
simple
IM & Presence, PIDF
SIP
sipping
Investigation, Event Package, 3GPP
speechse
MRCP, TTS
speermint
Session peering
xcom
Centrailzed conference
avt Audio/Video Transport
bliss Basic Level of Interoperability for SIP Services
drinks Data for Reachability of Inter/tra-NetworK SIP
ecrit Emergency Context Resolution with Internet Technologies
enum Telephone Number Mapping
geopriv Geographic Location/Privacy
iptel IP Telephony
mediactrl Media Server Control
mmusic Multiparty Multimedia Session Control
p2psip Peer-to-Peer Session Initiation Protocol
sigtran Signaling Transport
simple SIP for Instant Messaging and Presence Leveraging Extensions
sip Session Initiation Protocol
sipping Session Initiation Proposal Investigation
speechsc Speech Services Control
speermint Session PEERing for Multimedia INTerconnect
xcon Centralized Conferencing

48. ( ㅡ_-)’’ No. Is RFC WG remark title Rev. Status Abstract 1 RFC GEOPRIV
A Presence Architecture for the Distribution of GEOPRIV Location Object -
A protocol that carries PIDF_LO which used [I-D-SIP-location-Conveyance] 2
RFC 4119
A Presence-based GEOPRIV Location Object Format
Describes a Location-Object(LO) for carrying geographical information on the internet. 3
IMPP
RFC 2778
A Model for Presence and Instatnt Messaging
A Logical model for presence and instant messaging architecture 4
RFC 2779
Instatn Messaging / Presence Protocol Requirements
Defines a minimal set of requirements of IMPP 5
RFC 3859
Common Profile for Presence (CPP)
Defines common semantics and data formats for preence 6
RFC 3860
Common Profile for Instant Messaging (CPIM)
Defines common semantics and data formats for IM 7
RFC 3861
Address Resolution for Instant Messaging and Presence
Provides a guidance for locationg the resources associated with URIs using DNS, SRV 8
RFC 3863
Presence Information Data Format (PIDF)
A Definition for Presence Information Data Format (PIDF) as an Extension of XML 9
SIMPLE
RFC 4482
CIPID: Contact Information for the PIDF
Additional Contact Information to the Presentity 10
RFC 4660
Fuctional Description of Event Notification Filtering
Describes the opeations a subscriber performs in order to put filtering rules associated with a subscription 11
RFC 4662
A SIP Event Notification Extention for Resource Lists
A Subscribe mechanism for a list of resource, instade of send SUBSCRIBE to each resource 12
RFC 4481
Timed Presence Extensions to the PIDF to Indicate Status Information for Pas and Future Time Intervals
A PIDF extension for timed status information for a time interval fully in the future or the past 13
RFC 5263
SIP Extension for Partial Notification of Presence Information
Describes the partial notification mechanism 14
RFC 5262
PIDF Extension for Partial Prescnce
A Definition for using PIDF XML for partial presence 15
RFC 5264
Publication of Partial Presence Information
A mechanism for partial presence information 16
RFC 5196
SIP UA Capability Extension to PIDF
Defines a PIDF extension to represent SIP IA capabilities 17
RFC 4479
A Data Model for Presence
A definition to PIDF for presence and instant messaging 18
RFC 5025
Presecne Authorization Rules
Authorization rules for Presence 19
RFC 3856
A Presence Package for the SIP
Presence extension for the event package 20
RFC 4480
RPID: Rich Presence Extensions to the PIDF
An extension that adds optional elements to the PIDF 21
RFC 3857
A Watcher Information Event Templete-Package for the SIP
An event templete package for event notification for management watcher information that associated a resource 22
RFC 3858
An XML based Format for Watcher Information
A PIDF Definition for Watcher Information 23
RFC 4825
The XML Configuration Access Protocol(XCAP)
A protocol definition that can read, write, modify application in XML format on a server 24
RFC 4826
XML Formats for Representing Resource Lists
A Definition how to reprensenting resource list with XCAP 25
RFC 4827
An XCAP Usage for Manipulating Presence Document Contents
Describes a usage of the XCAP for manipulating the contents of PIDF 26
Draft
interdomain-scaling-analysis
Presence Interdomain Scalling Analysis for SIP/SIMPLE
Publication Requested
An analysis for presence and IM traffic as an informational doc. 27
view-sharing
Optimizing Federated Presence with View Sharing
Active
A traffic reduce method with view sharing associated I-D-interdomain-scaling-analysis 28
A SIP Event Package for the SIP
The usage of the SIP for subscriptions and notifications of presence 29
SIP
info-event
SIP INFO Method and Package Framework
Defines a event package for session defining, negotiation and exchanging with INFO method 30
location-conveyance
Location Conveyance for the SIP
Defines an extension to the SIP to convey geographic location information from one to another SIP entity 31
RFC 3515
The SIP Refer Method
Defines REFER method, refer event package and refer-to request header 32
SIPPING
presence-scaling-requirements
Scaling Requirements for Presence in SIP/SIMPLE
A set of requirements for enabling interdomain scaling on presence 33
cc-framework
A Call Control and Multi-party usage framework for the SIP
Define a framework and requirements for call control and multi party usage of SIP 34
cc-transfer
Session Initiation Protocol Call Control - Transfer
Waiting for AD
As a part of SIP Multipart call control - call transfer with REFER 35
config-framework
A Framework for SIP User Agent Profile Delivery
AD Evaluation
A Framework ro enable configuratio of SIP UA in SIP deployment 36
policy-package
A SIP Event Package for Session-specific Session Policies
IESG Evaluation
Enables UA to subacribe to session policy for a SIP session and to receive notifications, if it change 37
rtcp-summary
SIP Package for Voice Quaity Reporting Event
A Definition to enable the collection and reporting that measure the qualituy for VoIP sessions 38
gruu-reg-event
Registration Event Package Extention for SIP GRUUs
Last Call
Reg. event package (RFC3680) extention to GRUU for frequency unreachable 'contact' information 39
pending-additions
The SIP Pending Additions Event Package
RFC Ed. Queue
Defines a event package whereby user agent can subscribe to the consent-related state of the resources [ID-sip-consent-framework] that are being added to a resource list that defines translation 40
RFC 4575
A SIP Event Package for Conference State
A SIP Event Package for tightly coupled conferences using the SIP 41
RFC 4235
An INVITE-Initiated Dialog Event Package for the SIP
A Dialog event package for INVITE initiated dialog 42
RFC 4730
A SIP Event Package for Key Press Stimulus
Describes a KPML that enables monitoring of DTMF signals and user XML docs refered to as KPML 43
RFC 3842
A Message Summary and Message Waiting Infication Event Package for the SIP
A SIP Event Package to carry message waiting status and message summaries form a messaging systm to UA 44
RFC 4354
A SIP Event Package and Data Format for Various Setting in Support for the PTToCellular Service
Defines a SIP event package to support publication, subscription, and notification of additional capabilities for PoC 45
RFC 3680
A SIP Event Package for Registration
A Event Package for Register event occurred state 46
SPEERMINT
RFC 5344
Presence and Instant Messaging Peering Use Cases
Describes several user cases of peering of non-VoIP services between two or more Service Provider

49. SIP-overload WG Rate-based Overload Control
Limit the request rate a server receives from an upstream element.
Feedback: X requests per second.
Loss-based Overload Control
Reduce the request rate a server receives by a percentage X.
Feedback: reduce load by X%.
Window-based Overload Control
Limit the number of request a server can receive without confirming a request.
Feedback: send X more requests.
Overload Signal-based Overload Control
De-/increase of request rate until a target overload notification rate is reached.
Feedback: server overloaded (503 response without Retry–After header)

50. Any Questions