1. Diameter for LTE
By: Samuel Dratwa

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3. About the Copyright
This documentation is protected by Copyright © 2011 LOGTEL, 32 Shacham St., Petah Tikva, 49170, Israel. World rights reserved. The possession and use of this documentation is subjected to the restrictions contained in this license. No part of this documentation may be stored in a retrieval system, transmitted or reproduced in any way, including but not limited to photocopy, photograph, magnetic or other record, without the prior agreement and written permission of LOGTEL. Participants of this seminar are entitled to keep their copy of this documentation for references purposes only.

4. Agenda
Introduction
Overview of Diameter protocol and usage
Diameter message flow and message format
The need for DRA
The role of Diameter in EPC
The role of Diameter in IMS
The role of Diameter in roaming and hand-off
The role of Diameter in QoS and policies
Final exerciser (end to end flow)

5. It’s all about customer satisfaction
What are we selling ?
customer satisfaction !
It’s all about customer satisfaction

6. Diameter usage

7. What is Diameter? Next generation signaling protocol, replacing SS7
Exchange subscriber profile data between fundamental core network elements/systems:
IMS
EPC
Billing systems
Roaming exchanges

8. Charging / credit control DB inquiry Signaling (?)
Diameter usage
Diameter is an authentication, authorization, and accounting protocol for computer networks. It evolved from and replaces the much less capable RADIUS protocol that preceded it.
AAA
Charging / credit control
DB inquiry
Signaling (?)
The Diameter protocol was initially developed by Pat R. Calhoun, Glen Zorn, and Ping Pan in 1998 to provide a framework for authentication, authorization and accounting (AAA) that could overcome the limitations of RADIUS. 

9. Mapping SS7 protocols to SIP/Diameter

10. New Business Models Drive Diameter Signaling
Quality of Service
Location
Usage
Preferences
Service Tier
Personal Ads
Policy Control Drives Signaling
Guarantee quality of service for a video application
Provide subscriber profile, preferences or usage data to a mobile advertiser
Provide customized and dynamic service offerings for subscribers
Diameter signaling growth directly tied to how service providers are monetizing mobile data.
For example, as you add value to over-the-top applications by:
Guaranteeing quality of service for a video application
Providing subscriber profile, preferences or usage data to a mobile advertiser; or
Providing customized and dynamic service offerings for subscribers
Enabling two-sided business models with 3rd party content and application providers
more Diameter signaling is generated because this requires Diameter messages between policy servers, charging systems and subscriber databases.
And this is ‘good’ signaling because the more Diameter signaling the more successful you are at monetizing mobile data.

11. Rapid Diameter Signaling Growth
Diameter traffic worldwide will increase to more than 98 million MPS by 2017 (140% CAGR)
NA has the largest volumes overall
Other regions showing signs of traffic growth
LTE Penetration still projected at only 13% worldwide by 2017*
Pitch – Diameter Signaling Index just published and available at Open World
Growth driven by:
Subscriber growth
New LTE networks
Usage growth
New Business and monetization models
* Informa Telecoms & Media

12. Diameter Signaling Growth by Use Case
Policy is the top contributor to Diameter signaling
Online Charging (OCS) is the fastest growing use case
More complex policy rules adding to Diameter growth (i.e., Policy on the Device)
Mobility and Offline Charging other contributors
Future drivers include Service Delivery Applications
CAGR
163%
179%
75%
102%
Details available in Oracle Communications LTE Diameter Signaling Index
GLOBAL CAGR
Mobility 493, ,218 2,091,756 2,937,740 4,865,554 8,284, %
Policy 481,080 1,977,232 7,100,800 15,408,966 29,705,696 61,594, %
OFCS 134, , ,736 1,420,006 2,686,702 4,598, %
OCS 141, ,426 2,043,235 4,901,988 12,337,752 24,126, %
TOTAL MPS 1,249,623 3,791,565 12,019,527 24,668,700 49,595,703 98,603, %

13. Diameter Protocol

14. Diameter Packet format
Flags
"R" (Request) bit – If set, the message is a request. If cleared, the message is an answer.
"P" (Proxiable) bit – If set, the message MAY be proxied, relayed or redirected.
"E" (Error) bit – If set, the message contains a protocol error.
"T" (Potentially re-transmitted message) bit – This flag is set after a link failover procedure, to aid the removal of duplicate requests.

15. http://www. iana. org/assignments/aaa-parameters/aaa-parameters

16. Interoperability with RADIUS
Diameter is upwards compatible with RADIUS, so
Messages and AVPs
AVP codes is reused from RADIUS
Command codes is reused from RADIUS
Diameter NASREQ (RFC4005) maps RADIUS messages to/from Diameter AA-Request and AA-Answer message
Use of RADIUS<->Diameter Translation Agents

17. Interoperability with RADIUS (Cont’d)
Translations issues
Diameter messages can be larger than maximum RADIUS packet
Ongoing work
Mapping of new RADIUS extension types to Diameter
Usage of Nas-Port-Type and Service-Type vs. defining a new Application Id
Use of zero(0) AppId for all base protocol messages

18. Result-Code AVP
The Result-Code AVP (AVP Code 268) is of type Unsigned32 and indicates whether a particular request was completed successfully or an error occurred. All Diameter answer messages in IETF-defined Diameter application specifications MUST include one Result-Code AVP.
Diameter provides the following classes:
1xxx (Informational)
2xxx (Success)
3xxx (Protocol Errors)
4xxx (Transient Failures)
5xxx (Permanent Failure)

19. Error list Value Message Name Description 3001
DIAMETER_COMMAND_UNSUPPORTED
The Request contained a Command-Code that the receiver did not recognize or support.
3002
DIAMETER_UNABLE_TO_DELIVER
This error is given when Diameter can not deliver the message to the destination.
3003
DIAMETER_REALM_NOT_SERVED
The intended realm of the request is not recognized.
3004
DIAMETER_TOO_BUSY
When returned, a Diameter node should attempt to send the message to an alternate peer.
3005
DIAMETER_LOOP_DETECTED
An agent detected a loop while trying to get the message to the intended recipient.
3006
DIAMETER_REDIRECT_INDICATION
A redirect agent has determined that the request could not be satisfied locally.
3007
DIAMETER_APPLICATION_UNSUPPORTED
A request was sent for an application that is not supported.
3008
DIAMETER_INVALID_HDR_BITS
A request was received whose bits in the Diameter header were either set to an invalid combination.
3009
DIAMETER_INVALID_AVP_BITS
A request was received that included an AVP whose flag bits are set to an unrecognized value.
3010
DIAMETER_UNKNOWN_PEER
A CER was received from an unknown peer.

20. Diameter nodes and agents
Diameter is designed as a Peer-To-Peer architecture, and every host who implements the Diameter protocol can act as either a client or a server depending on network deployment.
Diameter nodes:
Diameter client
Diameter server
Diameter agents
Relay Agent
Proxy Agent
Redirect Agent
Translation Agent
Although the architecture just described looks like a traditional client-server architecture, a node acting as the Diameter server for some requests might actually act as a Diameter client in some situations; the Diameter protocol is actually peer-to-peer-based architecture in a more generic sense.

21. Proxy Agent

22. Redirect Agent
A Redirect Agent acts as a centralized configuration repository for other Diameter nodes. When it receives a message, it checks its routing table, and returns a response message along with redirection information to its original sender. This would be very useful for other Diameter nodes because they won't need to keep a list routing entries locally and can look up a Redirect Agent when needed. 

23. Translation Agent
The responsibility of this agent, is to convert a message from one AAA protocol to another. The Translation Agent is helpful for a company or a service provider to integrate the user database of two application domains, while keeping their original AAA protocols. Another situation is that a company wants to migrate to Diameter protocol, but the migration consists of many phases. The Translation Agent could provide the backward capability for a smooth migration.

24. Transport layer Protocols Security
Certain nodes MUST support at least SCTP or TCP (i.e. Diameter Client)
Others MUST support SCTP and TCP (i.e. Diameter Servers and Agents)
Security
TLS and IPSec
Selection Process (in order of execution)
IPSec, SCTP, TCP, TLS
SCTP or TCP is always attempted prior to capabilities exchange
TLS tried after capability negotiation
IPSec and TLS maybe used exclusively

25. Capabilities Negotiation
Capabilities Exchange
Use of Capabilities-Exchange (CER/CEA) messages
Message exchange advertises:
Peer Identity
Security schemes – Indicates the use of TLS
SCTP host addresses if used
CER/CEA may or may not be protected
Peer Table Creation
Lists all peers that passes capabilities negotiation
Indicates the connection status of each peers
Also used for message routing

26. Peer Liveness and Disconnection
Liveness Test
Use of Device-Watchdog exchange (DWR/DWA)
Aid in Failover performance: pro-active detection of failure
Disconnection
Use of Disconnect-Peer exchange (DPR/DPA)
Provides hints for future reconnection attempts
Routing table updates

27. Typical Diameter Exchanges
Client
Agent
Server
Peer Discovery
Discovery via DNS or Static Configuration
Peer Discovery
Capabilities Exchange Request
A Capabilities Exchange message carries a peer's identity and its capabilities (protocol version number, supported Diameter applications, etc.). A Diameter node only transmits commands to peers that have advertised support for the Diameter application associated with the given command.
Capabilities Exchange Request
Capabilities Exchange Answer
Capabilities Exchange Answer
Device Watchdog Request
Application-level heartbeat messages are used to proactively detect transport failures. These messages are sent periodically when a peer connection is idle and when a timely response has not been received for an outstanding request.
Device Watchdog Answer
Request
Request
There are two types of messages, Requests and Answers.. Every answer message carries a Result-Code AVP. The data value of the Result-Code AVP is an integer code indicating whether a particular request was completed successfully or whether an error occurred.
Answer
Answer

28. Diameter CER Example { Origin-Host } /* Required AVP, Occurrence: 1 */
<CER> ::= < Diameter Header: 257, REQ >
{ Origin-Host } /* Required AVP, Occurrence: 1 */
{ Origin-Realm }
1* { Host-IP-Address } /* Required AVP, Occurrence: 1+ */
{ Vendor-Id }
{ Product-Name }
[ Origin-State-Id ] /* Optional AVP, Occurrence: 0 or 1 */
* [ Supported-Vendor-Id ] /* Optional AVP, Occurrence: 0+ */
* [ Auth-Application-Id ]
* [ Inband-Security-Id ]
* [ Acct-Application-Id ]
* [ Vendor-Specific-Application-Id ]
[ Firmware-Revision ]
* [ AVP ]

29. Diameter Transport and Session-ID
Each Diameter process running on a host generates, or is configured with, a Diameter Identity. The Diameter Identity is a URI-syntax string with substrings representing the host's fully qualified domain name (FQDN), one of the ports used to listen for incoming connections, the transport used to listen for incoming connections (i.e. TCP or SCTP), the AAA protocol (i.e. Diameter), and the transport security (i.e. none or TLS).
The following is an example of a valid Diameter host identity:
aaa://host.abc.com:1812;transport=tcp;protocol=diameter
Sessions
Sessions AF
PCRF
AGW
TCP or SCTP Transport
TCP or SCTP Transport
A Diameter message pertaining to a specific user session includes a Session-Id AVP, the value of which is constant throughout the life of a session. The value of the Session-Id AVP is a globally and eternally unique text string, intended to uniquely identify a user session without reference to any other information.
The Diameter client initiating the session creates the Session-Id. The Session-Id begins with the originator's Diameter Identity string and is followed by any sequence guaranteeing both topological and temporal uniqueness.

30. Failover-Failback Procedure
Client
Relay
Server
1. Request
4. Answer
2. Request
T-bit set
3. Request
5. Answer
3. Answer
Request
Queue

31. Duplicate Detection Duplicates can occur Detection
Due to Failover
Nodes re-sending un-answered requests: Due to reboot
Detection
End-to-End Id is unique for a node
Re-sent request must have T-flag set
Therefore, use T-flag as a hint for possible duplication, then
Use End-to-End Id and Origin-Host AVP to detect duplication
Duplicate request SHOULD cause the same answer to be sent
Other Considerations
Use of Session-Id for duplicate detection in accounting records
Time needed to wait for duplicate messages

32. Diameter applications

33. What is Diameter Application ?
A Diameter Application is a protocol based on the Diameter base protocol defined in RFC 6733 (Obsoletes: RFC 3588). Each application is defined by an application identifier and can add new command codes and/or new mandatory AVPs. Adding a new optional AVP does not require a new application.
Examples of Diameter applications:
Diameter Mobile IPv4 Application (MobileIP, RFC 4004)
Diameter Network Access Server Application (NASREQ, RFC 4005)
Diameter Extensible Authentication Protocol Application (RFC 4072)
Diameter Credit-Control Application (DCCA, RFC 4006)
Diameter Session Initiation Protocol Application (RFC 4740)
Various applications in the 3GPP IP Multimedia Subsystem
Each interface in LTE

34. Credit Control Application Overview
Specified in RFC 4006
Can be used to provide real time credit control for various applications, e.g. messaging services, gaming services
Used between the network element providing the service (client) and credit control server (server)
Uses Application-Id 4

35. Credit Control Application Messages
Credit Control Request (CCR)
Sent from client to server to request authorization for a given service
Credit Control Answer (CCA)
Sent from server to client and carries the result of the corresponding authorization request
Reauthorization Request (RAR)
Sent by server to trigger a new CCR, e.g. after successful credit replenishment during a service
Reauthorization Answer (RAA)
Sent by client as an answer to RAR

36. Operation Modes Event Based Session Based
A single CCR/CCA exchange in each session
Used when it is sure that requested service event will be successful
Session Based
Multiple CCR/CCA exchanges in a session
Required when there is a need to reserve credits before providing the service
Requires state maintenance on the server side
Server first reserves the credits and debits them after receiving the subsequent CCR

37. Some important AVPs CC-Request-Type AVP CC-Request-Number AVP
Indicates type of the request for a CCR
Possible values are INITIAL_REQUEST, UPDATE_REQUEST, TERMINATION_REQUEST for session based scenarios and EVENT_REQUEST for event based scenarios
CC-Request-Number AVP
Identifies a request within a session
Requested-Action AVP
Used to indicate type of the requested action for event based scenarios. Possible values are DIRECT_DEBITING, REFUND_ACCOUNT, CHECK_BALANCE and PRICE_ENQUIRY

38. Event Based Scenario Example
Client
Server
CCR, Session-Id = S-Id1, Service-Identifier
CC-Request-Type = EVENT_BASED
Requested-Action = PRICE_ENQUIRY
CCA, Session-Id = S-Id1
Cost-Information
CCR, Session-Id = S-Id2, Subscription-Id,
CC-Request-Type = EVENT_BASED
Requested-Action = BALANCE_CHECK,
Service-Identifier
CCA, Session-Id = S-Id2
Check-Balance-Result
CCR, Session-Id = S-Id3, Service-Identifier
CC-Request-Type = EVENT_BASED
Requested-Action = DIRECT_DEBITING
Subscription-Id
CCA, Session-Id = S-Id3
Granted-Service-Unit

39. Session Based Scenario Example
Client
Server
CCR, Session-Id = S-Id1, Requested-Service-Unit
CC-Request-Type = INITIAL_REQUEST
Subscription-Id
CCA, Session-Id = S-Id1
Granted-Service-Unit, Validity-Time
CCR, Session-Id = S-Id1, Requested-Service-Unit,
CC-Request-Type = UPDATE_REQUEST
Subscription-Id
CCA, Session-Id = S-Id1
Granted-Service-Unit, Validity-Time
CCR, Session-Id = S-Id1,
CC-Request-Type = TERMINATION_REQUEST
Used-Service-Unit
CCA, Session-Id = S-Id1
Cost-Information

40. Credit Control Timers Tx timer Tcc timer
Used by client to guard against non-receipt of CCA after a CCR is sent
Can’t rely on Tw, configuring Tw to a low value may be undesirable and Tw on the whole message path may not be under control of the client administrating entity
Tcc timer
Used by server to guard against non-receipt of CCR for session based scenarios

41. Subsessions and Multiple Services
Multiple sub-sessions may be included in a credit control sessions. Each of them is identified by a unique CC-Sub-Session -Id AVP and have their own credit control life cycle
Credit control for multiple services could be performed in a credit control session
The goal is to limit use of network and client/server resources
Multiple-Services-Indicator AVP is sent by client to indicate support for multiple services
Multiple-Services-Credit-Control AVP carries credit control related information from server to client

42. Multiple Services Related Terms
Service-Id
Identifier for a specific service
Rating-Group
A group of services subject to the same cost and rating type
Quota
Authorized amount of resources for a specific service or rating group
Credit Pool
Authorized amount of resources for services/rating groups with different charging characteristics

43. Tariff-Change
Server can inform client when a tariff change will occur with Tariff-Time-Change AVP
Client reports used units before and after tariff change with Tariff-Change-Usage AVP

44. Duplicate Detection
Session-Id AVP, CC-Request-Number AVP and CC-Request-Type can be used to detect duplicates (mechanism described in RFC3588 will work too, i.e. using Origin-Host AVP and End-to-End Identifier

45. High Availability/Failure Handling Features
CC-Session-Failover AVP
Used by servers to inform clients whether a backup instance is present ( Client needs to know identity of backup peer by other means )
Credit-Control-Failure-Handling AVP
Used by server to inform client about the expected behavior for session based scenarios, when CCA for a CCR is not received
Direct-Debiting-Failure-Handling AVP
Used by server to inform client about the expected behavior for event based scenarios, when CCA for a CCR is not received

46. End of Tutorial
Thank You

47. DRA

48. For scalability and configuration simplicity an agent (similar to STP in SS7/SIGTRAN networks) links all the Diameter nodes (MME, HSS, PCEF, PCRF, OCS, OFCS, all IMS entities, etc.) and routes the Diameter requests/answers between them. All Diameter nodes have one entry in their routing table to deliver any DIAMETER message to the Agent. The Diameter agent is able to route between nodes of the same network or between nodes of different networks. To ensure availability, agents are deployed by matted pair. Every Diameter client or server is connected to the two Agents of that matted pair.

49. DRA advantages
Scalability - Considering N entities which need to interact with M entities, the number of TCP or SCTP connections between them is NxM if no Diameter agent is introduced. The number is N+M if an agent is present.
Simplification - The Diameter in the EPS leads to the update of the routing tables of all the entities which need to communicate with the new entity, if no agent is involved. With the presence of an agent, only the routing tables of the agent and the new entity are impacted.
Network interconnection with topology hiding - The agent enables simplifying the interconnection with other networks for the support of roaming agreements. The agent also hides the topology of the internal network.
Application layer routing - The agent enables performing application-based routing such as load balancing in the context of PCC (Policy and Charging Control), HSS identification in the case of interaction between MME and HSS, etc.
AAA protocol conversion - Translation agents are important when migration to Diameter occurs. They support interconnection with other domains applying other AAA protocols. As examples the DIAMETER agent may translate MAP into Diameter , CAP into Diameter , Diameter into RADIUS, etc.

50. Diameter Signaling and Control Network Resiliency
Prevent Failure, Avoid Outage, Assure Recovery
A robust Diameter signaling and control architecture must
DiameterServer
DiameterServer
Control amount of traffic to/from Clients and Servers
Detect and Route around congestion and failures
Orderly discard (based on Message Priority) of traffic from Client if needed
Facilitate Wi-Fi Offload using Analytics and other key indicators (i.e., Subscriber profile)
DSR
Diameter Client
Diameter Client
Diameter Client
In this network, the DSR and Policy on the device combine to prevent failure, avoid outage, assure recovery while maintaining quality of service.
Example 1: Preserve server due to signaling storm (ex. runaway client)
Meter & limit traffic toward Servers to prevent flooding the Servers
If congestion is detected, temporarily route to other servers
Meter & limit traffic from each client
Orderly discard (based on Message Priority) of traffic from Client if needed
Example 2: Prevent network outage upon server failure (ex. HSS goes down)
Detect failure, implement backup route to alternate Server – Client unaffected
Stricter throttling rules to manage Client traffic
Limit amount of traffic toward Server to prevent flooding
Orderly discard of traffic as needed
Example 3: Server recovery (ex. HSS comes back on line)
Control amount of traffic to allow orderly recovery of Server –prevent Server from oscillating
Manage Client traffic
Orderly discard of Diameter traffic from Client as needed
MPG – reduce messages to RAN
Problem – ANDSF use cases are limited
Static policies prevent smart offload scenarios that are needed to maximize revenue and improve customer experience
Solution – Policy-driven network selection
MPG extends real-time dynamic policy enforcement to devices, expanding the capabilities of Wi-Fi offload use cases
RAN – WIFI offload
Benefits – Extended Wi-Fi offload use cases using:
Subscriber profile
tier (gold vs. silver)
subscriber type (enterprise vs. consumer)
device type (smartphone vs. M2M device)
Quota status, e.g. offload out-of-credit subs
Roaming status
Application events
from OTT providers (e.g. start of video)
from TDFs e.g. content filter, CDN, cache
Time and/or location information
Device conditions, e.g. RSSI, GPS status
Analytics, e.g. congestion data
RAN
Diameter Client: MME, PGW, CSCF, AS, etc
Diameter Server: HSS, PCRF, OCS, OFCS, etc

53. Comparison of Diameter and RADIUS

54. Diameter in EPC/EPS

55. Interface list
S6 - enables transfer of subscription and authentication data for authenticating/authorizing user access to the EPS. This interface is between MME HSS
S13 - used for IMEI check. This interface is between MME and EIR (Equipment Identity Register)
Gx - allows the PCEF (i.e., PDN GW) obtaining policy and charging rules from the PCRF. With those rules, PCEF knows how to authorize/block/restrict IP flows and charge those flows.
Gy - online charging interface between PCEF and OCS
Gz - offline charging interface between PCEF and OFCS
S9 - the interface between the PCRF in a visited network and the PCRF in the home network. This interface is used when the PDN GW who terminates the bearers of the visiting user, belongs to the visited
Rx - enabling IMS to request access network resources (i.e., dedicated bearer) to guarantee the quality of service of the IMS sessions. Rx is between IMS and the PCRF.

56. EPS Architecture

57. EPS Architecture with DRA

58. PCC in an IMS Voice Call

59. EPS initial attach
29272

60. S13 Commands ECR
< ME-Identity-Check-Request > ::= < Diameter Header: 324, REQ, PXY, >
< Session-Id >
[ Vendor-Specific-Application-Id ]
{ Auth-Session-State }
{ Origin-Host }
{ Origin-Realm }
[ Destination-Host ]
{ Destination-Realm }
{ Terminal-Information }
[ User-Name ]
*[ AVP ]
*[ Proxy-Info ]
*[ Route-Record ]
29272

61. S13 Commands ECA
< ME-Identity-Check-Answer> ::=< Diameter Header: 324, PXY, >
< Session-Id >
[ Vendor-Specific-Application-Id ]
[ Result-Code ]
[ Experimental-Result ]
{ Auth-Session-State }
{ Origin-Host }
{ Origin-Realm }
[ Equipment-Status ]
*[ AVP ]
*[ Failed-AVP ]
*[ Proxy-Info ]
*[ Route-Record ]

62. Authentication-Information-Request (AIR)
< Authentication-Information-Request>::=<Diameter Header: 318, REQ, PXY, > < Session-Id > [ Vendor-Specific-Application-Id ] { Auth-Session-State } { Origin-Host } { Origin-Realm } [ Destination-Host ] { Destination-Realm } { User-Name } *[Supported-Features] [ Requested-EUTRAN-Authentication-Info ] [ Requested-UTRAN-GERAN-Authentication-Info ] { Visited-PLMN-Id } *[ AVP ] *[ Proxy-Info ] *[ Route-Record ]

63. Authentication-Information-Answer (AIA)
< Authentication-Information-Answer> ::=< Diameter Header: 318, PXY, > < Session-Id > [ Vendor-Specific-Application-Id ] [ Result-Code ] [ Experimental-Result ] [ Error-Diagnostic ] { Auth-Session-State } { Origin-Host } { Origin-Realm } * [Supported-Features] [ Authentication-Info ] *[ AVP ] *[ Failed-AVP ] *[ Proxy-Info ] *[ Route-Record ]

64. Diameter Update Location Request
MME updates the UE location in HSS
Origin and Destination are specified as Host and Realm
The user name in the request is set to IMSI
The Radio Access Technology is set to EUTRAN for LTE
The Visited PLMN is also included in the message

65. Update-Location-Request (ULR)
< Update-Location-Request> ::=< Diameter Header: 316, REQ, PXY, > < Session-Id > [ Vendor-Specific-Application-Id ] { Auth-Session-State } { Origin-Host } { Origin-Realm } [ Destination-Host ] { Destination-Realm } { User-Name } *[ Supported-Features ] [ Terminal-Information ] { RAT-Type } { ULR-Flags } [UE-SRVCC-Capability ] { Visited-PLMN-Id } [ SGSN-Number ] [ Homogeneous-Support-of-IMS-Voice-Over-PS-Sessions ] [ GMLC-Address ] *[ Active-APN ]
[ Equivalent-PLMN-List ]
[ MME-Number-for-MT-SMS ]
[ SMS-Register-Request ]
[ SGs-MME-Identity ]
[ Coupled-Node-Diameter-ID ]
*[ AVP ]
*[ Proxy-Info ]
*[ Route-Record ]

66. Diameter Update Location Answer
The HSS accesses the database and responds with user information to the MME
The Aggregate Maximum Bit Rate (AMBR) occurs twice in the message:
The first occurrence specifies the maximum bit rate for the default PDP
The second occurrence specifies the maximum data limit via the APN.
APN configuration includes: IP address of the PDN Gateway. This address is used to determine the default route for the traffic towards the Internet

67. Insert-Subscriber-Data-Request (IDR)
< Insert-Subscriber-Data-Request> ::=< Diameter Header: 319, REQ, PXY, > < Session-Id > [ Vendor-Specific-Application-Id ] { Auth-Session-State } { Origin-Host } { Origin-Realm } { Destination-Host } { Destination-Realm } { User-Name } *[ Supported-Features] { Subscription-Data} [ IDR- Flags ] *[ AVP ] *[ Proxy-Info ] *[ Route-Record ]

68. Subscription-Data AVP
Subscription-Data ::= <AVP header: > [ Subscriber-Status ] [ MSISDN ] [ A-MSISDN ] [ STN-SR ] [ ICS-Indicator ] [ Network-Access-Mode ] [ Operator-Determined-Barring ] [ HPLMN-ODB ] *10[ Regional-Subscription-Zone-Code] [ Access-Restriction-Data ] [ APN-OI-Replacement ] [ LCS-Info ] [ Teleservice-List ] *[ Call-Barring-Info ]
[ 3GPP-Charging-Characteristics ] [ AMBR ] [ APN-Configuration-Profile ] [ RAT-Frequency-Selection-Priority-ID ] [ Trace-Data] [ GPRS-Subscription-Data ] *[ CSG-Subscription-Data ] [ Roaming-Restricted-Due-To-Unsupported-Feature ] [ Subscribed-Periodic-RAU-TAU-Timer ] [ MPS-Priority ] [ VPLMN-LIPA-Allowed ] [ Relay-Node-Indicator ] [ MDT-User-Consent ] [Subscribed-VSRVCC ] [Subscription-Data-Flags ] *[ AVP ]

69. Insert-Subscriber-Data-Answer (IDA)
< Insert-Subscriber-Data-Answer> ::= < Diameter Header: 319, PXY, > < Session-Id > [ Vendor-Specific-Application-Id ] *[ Supported-Features ] [ Result-Code ] [ Experimental-Result ] { Auth-Session-State } { Origin-Host } { Origin-Realm } [ IMS-Voice-Over-PS-Sessions-Supported ] [ Last-UE-Activity-Time ] [ RAT-Type ] [ IDA-Flags ] [ EPS-User-State ] [ EPS-Location-Information ] [Local-Time-Zone ] *[ AVP ] *[ Failed-AVP ] *[ Proxy-Info ] *[ Route-Record ]

70. EPS initial attach (cont.)

71. (CCR for Gx (based on DCCA
<CC-Request> ::= < Diameter Header: 272, REQ, PXY >
< Session-Id >
{ Auth-Application-Id }
{ Origin-Host }
{ Origin-Realm }
{ Destination-Realm }
{ CC-Request-Type }
{ CC-Request-Number }
[ Credit-Management-Status ]
[ Destination-Host ]
[ Origin-State-Id ]
*[ Subscription-Id ]
*[ Supported-Features ]
[ TDF-Information ]
[ Network-Request-Support ]
*[ Packet-Filter-Information ]
[ Packet-Filter-Operation ]
[ Bearer-Identifier ]
[ Bearer-Operation ]
[ Dynamic-Address-Flag ]
[ Dynamic-Address-Flag-Extension ]
[ PDN-Connection-Charging-ID ]
[ Framed-IP-Address ]
[ Framed-IPv6-Prefix ]
[ IP-CAN-Type ]
[ 3GPP-RAT-Type ]
[ RAT-Type ]
[ Termination-Cause ]
[ User-Equipment-Info ]
[ QoS-Information ]
[ QoS-Negotiation ]
[ QoS-Upgrade ]
[ Default-EPS-Bearer-QoS ]
[ Default-QoS-Information ]
0*2[ AN-GW-Address ]
[ AN-GW-Status ]
[ 3GPP-SGSN-MCC-MNC ]
[ 3GPP-SGSN-Address ]
[ 3GPP-SGSN-IPv6-Address ]
[ 3GPP-GGSN-Address ]
[ 3GPP-GGSN-IPv6-Address ]
[ 3GPP-Selection-Mode ]
[ RAI ]
[ 3GPP-User-Location-Info]
[ User-Location-Info-Time ]
[ User-CSG-Information ]
[ TWAN-Identifier ]
[ 3GPP-MS-TimeZone ]
[ 3GPP-Charging-Characteristics ]
[ Called-Station-Id ]
[ PDN-Connection-ID ]
[ Bearer-Usage ]
[ Online ]
[ Offline ]
*[ TFT-Packet-Filter-Information ]
*[ Charging-Rule-Report ]
*[ Application-Detection-Information ]
*[ Event-Trigger ]
[ Event-Report-Indication ]
[ Access-Network-Charging-Address ]
*[ Access-Network-Charging-Identifier-Gx ]
*[ CoA-Information ]
*[ Usage-Monitoring-Information ]
[ Routing-Rule-Install ]
[ Routing-Rule-Remove ]
[ HeNB-Local-IP-Address ]
[ UE-Local-IP-Address ]
[ UDP-Source-Port ]
[ Logical-Access-ID ]
[ Physical-Access-ID ]
*[ Proxy-Info ]
*[ Route-Record ]
*[ AVP ]

72. CCR for Gx (cont.) [ Termination-Cause ] [ User-Equipment-Info ]
[ QoS-Information ]
[ QoS-Negotiation ]
[ QoS-Upgrade ]
[ Default-EPS-Bearer-QoS ]
[ Default-QoS-Information ]
0*2[ AN-GW-Address ]
[ AN-GW-Status ]
[ 3GPP-SGSN-MCC-MNC ]
[ 3GPP-SGSN-Address ]
[ 3GPP-SGSN-IPv6-Address ]
[ 3GPP-GGSN-Address ]
[ 3GPP-GGSN-IPv6-Address ]
[ 3GPP-Selection-Mode ]
[ RAI ]
[ 3GPP-User-Location-Info]
[ User-Location-Info-Time ]
[ User-CSG-Information ]
[ TWAN-Identifier ]
[ 3GPP-MS-TimeZone ]
[ 3GPP-Charging-Characteristics ]
[ Called-Station-Id ]
[ PDN-Connection-ID ]
[ Bearer-Usage ]
[ Online ]
[ Offline ]
*[ TFT-Packet-Filter-Information ]
*[ Charging-Rule-Report ]
*[ Application-Detection-Information ]
*[ Event-Trigger ]
[ Event-Report-Indication ]
[ Access-Network-Charging-Address ]
*[ Access-Network-Charging-Identifier-Gx ]
*[ CoA-Information ]
*[ Usage-Monitoring-Information ]
[ Routing-Rule-Install ]
[ Routing-Rule-Remove ]
[ HeNB-Local-IP-Address ]
[ UE-Local-IP-Address ]
[ UDP-Source-Port ]
[ Logical-Access-ID ]
[ Physical-Access-ID ]
*[ Proxy-Info ]
*[ Route-Record ]
*[ AVP ]
[ Offline ]
*[ TFT-Packet-Filter-Information ]
*[ Charging-Rule-Report ]
*[ Application-Detection-Information ]
*[ Event-Trigger ]
[ Event-Report-Indication ]
[ Access-Network-Charging-Address ]
*[ Access-Network-Charging-Identifier-Gx ]
*[ CoA-Information ]
*[ Usage-Monitoring-Information ]
[ Routing-Rule-Install ]
[ Routing-Rule-Remove ]
[ HeNB-Local-IP-Address ]
[ UE-Local-IP-Address ]
[ UDP-Source-Port ]
[ Logical-Access-ID ]
[ Physical-Access-ID ]
*[ Proxy-Info ]
[ Route-Record ]
*[ AVP ]

73. CCA for Gx
<CC-Answer> ::= < Diameter Header: 272, PXY > < Session-Id > { Auth-Application-Id } { Origin-Host } { Origin-Realm } [ Result-Code ] [ Experimental-Result ] { CC-Request-Type } { CC-Request-Number } *[ Supported-Features ] [ Bearer-Control-Mode ] *[ Event-Trigger ] [ Event-Report-Indication ] [ Origin-State-Id ] *[ Redirect-Host ] [ Redirect-Host-Usage ] [ Redirect-Max-Cache-Time ] *[ Charging-Rule-Remove ] *[ Charging-Rule-Install ] [ Charging-Information ] [ Online ] [ Offline ] *[ QoS-Information ] [ Revalidation-Time ] [ Default-EPS-Bearer-QoS ] [ Default-QoS-Information ] [ Bearer-Usage ] *[ Usage-Monitoring-Information ] *[ CSG-Information-Reporting ] [ User-CSG-Information ] [ Session-Release-Cause ] [ Error-Message ] [ Error-Reporting-Host ] *[ Failed-AVP ] *[ Proxy-Info ] *[ Route-Record ] *[ AVP ]
*[ QoS-Information ]
[ Revalidation-Time ]
[ Default-EPS-Bearer-QoS ]
[ Default-QoS-Information ]
[ Bearer-Usage ]
*[ Usage-Monitoring-Information ]
[ CSG-Information-Reporting ]
[ User-CSG-Information ]
[ Session-Release-Cause ]
[ Error-Message ]
[ Error-Reporting-Host ]
*[ Failed-AVP ]
*[ Proxy-Info ]
*[ Route-Record ]
*[ AVP ]

75. Cancel-Location-Request (CLR)
< Cancel-Location-Request> ::=< Diameter Header: 317, REQ, PXY, > < Session-Id > [ Vendor-Specific-Application-Id ] { Auth-Session-State } { Origin-Host } { Origin-Realm } { Destination-Host } { Destination-Realm } { User-Name } *[Supported-Features ] { Cancellation-Type } [ CLR-Flags ] *[ AVP ] *[ Proxy-Info ] *[ Route-Record ]

76. Cancel-Location-Answer (CLA)
< Cancel-Location-Answer> ::= < Diameter Header: 317, PXY, > < Session-Id > [ Vendor-Specific-Application-Id ] *[ Supported-Features ] [ Result-Code ] [ Experimental-Result ] { Auth-Session-State } { Origin-Host } { Origin-Realm } *[ AVP ] *[ Failed-AVP ] *[ Proxy-Info ] *[ Route-Record ]

77. EPS Detach ?

78. Command-Code for S6a/S6d
Command-Name
Abbreviation
Code
Update-Location-Request
ULR
316
Update-Location-Answer
ULA
Cancel-Location-Request
CLR
317
Cancel-Location-Answer
CLA
Authentication-Information-Request
AIR
318
Authentication-Information-Answer
AIA
Insert-Subscriber-Data-Request
IDR
319
Insert-Subscriber-Data-Answer
IDA
Delete-Subscriber-Data-Request
DSR
320
Delete-Subscriber-Data-Answer
DSA
Purge-UE-Request
PUR
321
Purge-UE-Answer
PUA
Reset-Request
RSR
322
Reset-Answer
RSA
Notify-Request
NOR
323
Notify-Answer
NOA

79. Inter-MME Tracking Area Update
Analysis of Use Cases Example from 3GPP, Concern about signaling volume
HSS
Home Subscriber Server
Diameter on S6a
Update Location Request
MME
MME
Mobility Management Entity
Location Update (new Tracking Area)
Inter-MME Tracking Area Update

80. Grouping APVs for bulk signaling (in the order of efficiency)
Group-ID identifies multiple users, list of attributes/values applies to all users of the group
List of Session-IDs identifies a group of users, list of attributes/values applies to all users of the group
List of Session-IDs identifies multiple users, each Session-ID has an individual list of AVPs associated
Diameter Hdr
[Session-ID]
AVP 1
Group-ID
AVP 2
AVP N
Session-ID 1
Session-ID K
AVP 1.1
AVP K.1
AVP 1.2
AVP 1.N
AVP K.2
AVP K.N

81. References
ETSI TS , Resources and Admission Control Subsystem (RACS); Re interface based on the Diameter protocol
3GPP TS , Mobility Management Entity (MME) and SGSN related interfaces based on the Diameter protocol
3GPP TS , Study on PCRF Failure and Restoration
TD S , Contribution to 3GPP TSG SA2 WG2 meeting #86, July 2011, Core Network Overload Solution Study
Scope: Identify and document scenarios, that may result in signaling overload
State restoration after reboot, results in burst of re-registrations from mobile nodes

82. Diameter in IMS
(VoLTE)

83. Why do we need VoLTE ?
Why not use VoIP solution like Skype ?

84. Different approach to Voice in LTE
CSFB (Circuit Switched Fallback): In this approach, LTE just provides data services, and when a voice call is to be initiated or received, it will fall back to the CS domain. When using this solution, operators just need to upgrade the MSC instead of deploying the IMS, and therefore, can provide services quickly. However, the disadvantage is longer call setup delay.
SVLTE (Simultaneous Voice and LTE): In this approach, the handset works simultaneously in the LTE and CS modes, with the LTE mode providing data services and the CS mode providing the voice service. This is a solution solely based on the handset, which does not have special requirements on the network and does not require the deployment of IMS either. The disadvantage of this solution is that the phone can become expensive with high power consumption.

85. Telstra decided not use VoLTE

86. VoLTE vs. VOIP Why not use VoIP solution like Skype ?
VoLTE (TAS/MMTEL) supply:
Emergency services
Legacy services
Class services
Scalability
Robustness
Reliability
(high) Availability

87. CLASS (Custom Local Area Signaling Services)
AKA VSC (vertical service code) - developed by AT&T in the 1960s
a special code dialed prior to (or instead of) a telephone number that engages some type of special telephone service
Anonymous Call Rejection: start
Anonymous Call Rejection : cancel
Busy Number Redial : start
Busy Number Redial : cancel
Call Forwarding: start
Call Forwarding: cancel
Call Return (incoming)
Call Waiting disable
Caller ID Disable

88. TAS/MMTel features

89. MMTel Originating Features
TIP (Terminating Identification Presentation)
OIR (Originating Identification Restriction)
Hotlining
OCB (Outgoing Call Barring)
Barring of All Outgoing Calls
Barring of All Outgoing International Calls
Dialing Plans (Number Analyzer component )
7,10,11 digit dialing
0,0+,01+,00 dialing
Vanity number support (12+ digits)
Abbreviated Dialing Codes (ADC) commercial and non-commercial
N11
VSC
International Dialing
N-way Conferencing (6-way)
Call Hold (CH)
Cell ID Validation
IR.94 (video support)
Soft phone (including emergency call)
System announcements
Smart Limits (SLW)
Postpaid charging
Prepaid

90. MMTel Terminating Features
OIP (Originating Identification Presentation)
TIR (Terminating Identification Restriction)
Hotlining
ICB (Incoming Call Barring)
Barring of all Incoming Calls
Block List
DND
CDIV (Call Diversion)
CFU (Call Forwarding Unconditional)
CFNL (CF on Non-Login)
CFB (CF on Busy)
CFNR (CF on Non-Reply)
CFNRC (CF on Non-Reachable)
Call Waiting (CW)
Routing To Voic
Call Hold (CH)
Cell ID Validation
IR.94 (video support)
Soft phone (including emergency call)
System announcements
Smart Limits (SLW)
Postpaid charging
Prepaid

91. High Level call flow

92. Basic TAS call flow – LTE Originating

93. Basic TAS call flow – LTE Originating
UE A originates a call to UE B. Follow the registration path, UE A sends SIP INVITE message to P-CSCF and P-CSCF forwards it to S-CSCF.
S-CSCF checks the iFC for UE A for originating processing. It determines that it needs to invoke SCC-AS processing first. Then it sends SIP INVITE to SCC-AS.
After SCC-AS processing, SCC-AS acts as B2BUA and sends SIP INVITE back to S-CSCF
Based on iFC for UE A, TAS is invoked as the 2nd AS for originating processing. S-CSCF sends SIP INVITE to TAS. After TAS finishes its processing, it acts as B2BUA and sends the call back to S-CSCF
Based on iFC for UE A, there is no more AS that needs to be invoked for originating processing. S-CSCF performs ENUM query.
ENUM returns with B party’s domain name, S-CSCF looks up the internal routing table and maps B party’s domain name to the terminating network I-CSCF domain name. DNS query is performed for S-CSCF to route the request to terminating network’s I-CSCF. Continue with IMS termination call flow.
Continue with LTE termination in the call termination part of the call flow.

94. Basic TAS call flow – LTE Terminating

95. Basic TAS call flow – LTE Terminating
UE B initiate a call to A.
Follow the normal IMS termination process, the call is routed to IMS core I-CSCF and S-CSCF.
I-CSCF performs HSS-IMS query for selecting the appropriate S-CSCF and sends SIP INVITE to UE A’s S-CSC.
Based on A party’s terminating iFC, S-CSCF sends SIP INVITE to TAS as the first AS for terminating processing. Acting as SIP B2BUA TAS sends SIP INVITE back to S-CSCF.
S-CSCF determines that SCC-AS needs to be accessed as the 2nd /last AS for UE A. S-CSCF sends SIP INVITE to SCC-AS.
SCC-AS sends the call back to the S-CSCF. S-CSCF determines that all terminating processing for UE A has finished, it starts to terminate the call to the terminating party.
Based on the registered Contact information, S-CSCF sends SIP INVITE to the P-CSCF.
P-CSCF sends SIP INVITE to the terminating UE A

96. 1. P-CSCF  S-CSCF : Invite

97. SDP

98. 2. S-CSCF  P-CSCF : 100 trying

99. 3. S-CSCF  SCC AS : Invite

100. 4 . SCC AS  S-CSCF : 100 trying

101. VoLTE detailed services flows

102. Schematic sequence flow

103. Simple Originating and terminating flow

104. Diameter AVPs Accounting-Record-Type START Service-Information:
Value
Accounting-Record-Type
START
Service-Information:
Subscription-Id : Subscription-Id-Type
1 (END_USER_IMSI)
Subscription-Id : Subscription-Id-Data
Served User IMSI
IMS-Information: Role-of –node
Originating
IMS-Information: Node-Functionality
AS (6)
IMS-Information: Access-Network-Information
‘P-Access-Network-Info’ header from the incoming INVITE ( step 2)
IMS-Information: User-Session-ID
‘Call-ID’ header value of incoming INVITE (step 2)
IMS-Information: Outgoing-Session-ID
‘Call-ID’ header value of outgoing INVITE (step 5)
IMS-Information: Calling-Party-Address
Alice’s URIs, set from ’P-Asserted-Identity’ header of the incoming INVITE. (step 2)
IMS-Information: Called-Party-Address
Bob’s URI set in Request-URI of outgoing INVITE (step 5)
IMS-Information: Called-Asserted-Identity
Bob’s URI, set from ’P-Asserted-Identity’ header of the received 18x or 200 OK INVITE response. The number of AVPs depends on the number of ‘P-Asserted-Identity’ headers received in the INVITE response. ( step 8 or 12)
IMS-Information: Alternate-Charged-Party-Address
Should be specified with the value set in ‘CHARGED_NUMBER’ parameter of the served user profile if it is not equal to user’s MSISDN
IMS-Information : IMS Charging Identifier
Contains the ICID found in the ‘P-Charging Vector’ (‘icid-value’ parameter) of the incoming INVITE (step 2)
IMS-Information:IMS-Communication-Service-Identifier
‘ICSI’ parameter from ‘P-Asserted-Service’ header or ‘icsi’ media-feature tag from ‘Contact’ header if exists in the incoming INVITE (step 2)
IMS-Information: Number-Portability-Routing-Information
‘rn=’ parameter , if exists, from ‘Request-URI’ header of the incoming INVITE (step 2)
IMS-Information: Event-Type: SIP-Method
INVITE
IMS-Information: Inter-Operator-Identifier : Originating-IOI
‘orig-ioi’ parameter in the incoming INVITE ‘P-Charging –Vector’ (step 2)
IMS-Information: Inter-Operator-Identifier : Terminating-IOI
‘term-ioi’ parameter received in the 200 ok in ‘P-Charging-Vector’ ( if exists) (step 12)
IMS-Information :Time-Stamps
IMS-Information :Time-Stamps : SIP-Request-Timestamp
Time when INVITE request was received (step 2)
IMS-Information :Time-Stamps: SIP-Request-Timestamp-Fraction
Milliseconds fraction in relation to SIP-Request-Timestamp
IMS-Information :Time-Stamps : SIP-Response-Timestamp
Time when 200 OK received (step 12)
IMS-Information :Time-Stamps: SIP-Response-Timestamp-Fraction
Milliseconds fraction in relation to SIP-Response-Timestamp
IMS-Information : SDP-Session-Description
v=0
o=Bob IN IP
s=-
i=A Seminar on the session description protocol
c=IN IP
b=CT:1024
IMS-Information: SDP-Session-Description t=
a=sendrecv
IMS-Information: SDP-Media-Component: SDP-Media-Name
m=audio RTP/AVP 0
Bob’s SDP received in the step 12
IMS-Information: SDP-Media-Component: SDP-Media-Description
i=audio media
b=CT:1000
k=prompt
IMS-Information: SDP-Media-Component: SDP-Type
1 ( SDP answer)
m=video RTP/AVP 99 90
i=video media
a=rtpmap:90 h /90000
0 ( SDP offer)
MMTEL-Information: Subscriber-Role
0 (originating)

105. The terminating side

106. How to decide if it’s ORIG or TERM

107. CFx high level TAS Alice Term S-CSCF Alice TAS Alice Orig S-CSCF Bob

113. Diameter AVPs

114. Conference

115. ADC (as 3rd party VAS AS)

116. RCS (Rich Communication Suite)
RCS 5.1 provides a framework for discoverable and interoperable advanced communication services and detailed specifications for a basic set of advanced communication services. RCS 5.1 builds on the fundamentals from RCS Release 1 to 4, RCS-e (RCS-enhanced) and RCS 5.0

117. RCS AS
XML Document Management Server (XDMS) is a functional element responsible for handling the management of user XML documents stored on the network side, such as presence authorization rules, static presence information, contact and resource lists.
Resource List Server (RLS) handles subscriptions to presence lists. It creates and manages back-end subscriptions to all resources in the presence list. The list content is retrieved from the XDM Server.
Manages publications from one or multiple presence source(s) of a certain presentity. This includes refreshing presence information, replacing existing presence information with newly-published information, or removing presence information.
Manages subscriptions from watchers to presence information and generates notifications about presence information state changes, retrieving the presence authorization rules from the XDM Server.

119. messaging interworking with MMS

120. Roaming

121. LTE roaming overview Attachment procedure Authentication procedure
Update location procedure
Subscriber data retrieval procedure
Policy exchange
Roaming border
Visited network
Home network
MME
PCRF
PCRF
HSS 1
Attach
1: UE initiates attach request to visited network
2: Visited network MME authenticates user with home network HSS
3: MME in visited network updates user location in HSS at home network
4: Home network HSS sends subscriber data (service and policy authorizations) to visited network MME
5 Home PCRF sends policies for voice and data treatment to Visited PCRF
Subscriber policy provided by home HSS
DIAMETER signaling between Visited MSP MME & Home
Mobility Management Entity is the main signaling node in the EPC. It is responsible for initiating paging and authentication of the mobile device. 2
Authenticate 2
Authenticate 3
Update Location 4
Subscriber Data
Policy exchange 5

122. Diameter is the key roaming protocol
S6a Diameter (3GPP TS )
AAA interface between visited MME and home HSS
Transfers subscription, location and authentication data for authenticating user access to visited EPS
S9 Diameter interface (TS )
Policy interface between the Home PCRF and Visited PCRF
Transfers QoS policy and charging control information
Visited MNO
MME
HSS
Home MNO
Visited MNO
PCRF
Home MNO

123. VoLTE roaming options
Home routed with data backhaul to home network (existing data model)
Distributed policy control with policy interfaces
Visited P-CSCF with policy control in visited network (selected by GSMA IR.92)
Visited services with IMS core in visited network
eUTRAN
H-PCRF
V-PCRF
Distributed
Policy Control
eUTRAN
PCRF
Visited
P-CSCF
eUTRAN
PCRF
Visited
Services
eUTRAN
Home Routed
PCRF
Home
network
Visited
network
123

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