Diameter and SBBC Concepts

Camiant Inc

Base Protocol and Applications

DIAMETER Base Protocol

NASREQ

Applications

EAP

Applications

Mobile IP V4

Applications

Credit Control

Applications

Other 3GPP

Cx, Dx, Sh, Ro, Rf

• The Diameter Base Protocol provides reliable transport and delivery of messages

• The Base Protocol must be used along with an application

DIAMETER Base Commands

DIAMETER Base Protocol

NASREQ

Applications

EAP

Applications

Mobile IP V4

Applications

Credit Control

Applications

Tx

Application

Other 3GPP

Cx, Dx, Sh, Ro, Rf

Ty

Application

3. Credit-Control Messages

This section defines new Diameter message Command-Code values that

MUST be supported by all Diameter implementations that conform to

this specification. The Command Codes are as follows:

Command-Name Abbrev. Code Reference

---------------------------------------------------------------------------------

Credit-Control-Request CCR 272 3.1

Credit-Control-Answer CCA 272 3.2

3. NAS Messages

This section defines the Diameter message Command-Code [BASE] values

that MUST be supported by all Diameter implementations conforming to

this specification. The Command Codes are as follows:

Command-Name Abbrev. Code Reference

---------------------------------------------------------------------------------------------------------

AA-Request AAR 265 3.1

AA-Answer AAA 265 3.2

Tx, and Ty Applications

In addition to the AVPs defined within the clause 6.4, the Diameter AVPs from the Diameter base application (RFC 3588 [2]) are reused within the Diameter messages of the Tx application. The support of AVPs from the Diameter Network Access Server Application (NASREQ) [3] is not required from Diameter implementations that conform to the present document.

Accounting functionality (Accounting Session State Machine, related command codes and AVPs) is not used in the Tx interface.

The Tx application is defined as an IETF vendor specific Diameter application with application ID 16777222, where the vendor is 3GPP. The vendor identifier assigned by IANA to 3GPP (http://www.iana.org/assignments/enterprise-numbers) is 10415.

Need to define an application ID For Ty

Diameter Node Types

Some PCRF functions can be associated with a home network for the purpose of representing subscription and home based application function information. Some PCRF functions can be associated with the network of the Access Gateway for purpose of enforcement of local policy. In roaming situations where the Access Gateway is located in a visited network, there may be both home and serving network PCRFs. In this case the serving network PCRF may act as a proxy or redirect agent for communications to/from the Access Gateway and the home PCRF (also see section 5.3.5).

5.1.2.3 Application Function

Diameter Peers

Diameter peers, the set of Diameter nodes with which a given Diameter node will directly communicate, may be statically configured or may be dynamically discovered using SLPv2 or DNS SRV RRs.

Capabilities Exchange

The first Diameter messages exchanged between two Diameter peers, after establishing the transport

connection, are Capabilities Exchange messages. 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.

Typical Diameter Exchanges

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.

Discovery via DNS or Static Configuration

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.

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.

Peer Discovery

Peer Discovery

Capabilities Exchange Request

Capabilities Exchange AnswerCapabilities

Exchange Answer

Capabilities Exchange Request

Device Watchdog Request

Device Watchdog Answer

Request

AnswerAnswer

Request

Client ServerAgent

Diameter Transport and Session-ID

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.

TCP or SCTP Transport

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

PCRF

SessionsSessions

TCP or SCTP TransportAF AGW

SBBC Applications

SBBC Authorization on Initial Attach

Peer Discovery

Peer Discovery

Capabilities Exchange Request

Capabilities Exchange AnswerCapabilities

Exchange Answer

Capabilities Exchange Request

Device Watchdog Request

Device Watchdog Answer

CC Request

CCAnswer

CC Answer

CC Request

Client ServerAgent

On MS Attach a Diameter Session is established between the AGW and the PCRF on behalf of the MS (With Diameter CCR and CCA messages using Ty Application ID with CCR Request Type set to INITIAL REQUEST)

This Session lasts for as long as the Mobile is attached and is used for all transaction between the AGW and PCRF including:

• Authorization of Bear establishment/modification

• Notification of Loss or release of bearer

AND all transactions between the PCRF and the AGW including

• PCRF initiated “Push” for QoS

• PCRF initiated removal of resources

• PCRF initiated Opening or Closing of Gates

AGW PCRFoptional

5.2.1 Ty Diameter messages

Ty Messages are carried within the Diameter Application(s) described in the sub-clauses below. These Applications are defined as vendor specific Diameter applications. The vendor identifier assigned by IANA to 3GPP is 10415.

The association between the PDS session and the Diameter Credit Control sessions shall be done in a one-to-one basis (i.e. 1 PDS session = 1 DCC session), and each service instance shall map to a Diameter sub-session (i.e. 1 service instance = 1 DCC sub-session). The release of the last service instance shall be indicated by the release of the whole DCC session, whereas release of a single service instance, with others remaining, shall be indicated by the release of the sub-session corresponding to that service instance.

“Easy” Applications

Simple Bearer Authorization at the PCRF

e.g. no IMS or AF present. (Note Changes to the Diagram.) Each bearer uses a Diameter sub-session ID

How does the PCRF know that no AF initiated Push is coming for this bearer?

Simple AF initiated “Push” of IP QoS

For example on a EV-DO Rel 0, PCRF pushes, IP level Policing, Shaping, and/or Queueing commands along with a classifier determined from the AF. Note Changes to the Diagram. Each Push uses a Diameter sub-session ID

How does the PCRF know that no MS initiated Pull is coming for this session?

Push/ Pull Applications

Current Network Supports Pull e.g. Rev A no fallback

Handset supports pull

Application Client requests Pull

PDSN allows Pull

PCRF receives Pull to match Push

MS 1 X X X X YES

MS 2 X X X NO

MS 3 X X X NO

MS….n NO

Network’s contain a varied mixture of terminals and clients. It virtually impossible to determine whether it is reasonable to expect a for a given IP classifier at a given time.

How does the PCRF know that no AF initiated Push is coming for this bearer?

How does the PCRF know that no MS initiated Pull is coming for this session?

How can the PCRF correlate the IP Classifier from the AF with the TFT from an MS initiated Bearer initiation/modification

Subsequent AF sessions may use the same bearer. i.e. AF and bearer session tear down are currently not coordinated

AF MS MSPCRF PCRF PCRFAF AFMS

Push arrives at PCRF before Pull

Push arrives at PCRF after Pull

Push arrives at PCRF at the same time as Pull

Push and pull for a given transaction can arrive at different times. What timers would be needed?

Network’s contain a varied mixture of terminals and clients. It virtually impossible to determine whether it is reasonable to expect a for a given IP classifier at a given time.

“Independent Push/Pull” Policy and Charging Rules

Diameter Session IDs created at MS attach

TCP or SCTP Transport

MS 1

MS 2

Diameter Sub-Session IDs created at bearer creation

Diameter Sub-Session IDs created from AF Push

• Diameter session Created at MS Attach• Independent Sub-sessions created for bearer creation and AF Push

– AF Push with Bearer Pull will use 2 Gates and the Policy Decision Rules are evaluated 2 times- once for the IP Push, and once for the Bearer Pull

• IP QoS gates– can be used for application-level, access-network independent, admission control and

charging rules – can also push an IP-level enforcement envelope for bearers, e.g silver subscriber get 512 K

for video streaming.– IP QoS primitive can include per subscriber, per flow policing, shaping, and queuing

Diameter Sub-Session IDs created at bearer creation

Diameter Sub-Session IDs created from AF Push

“Independent Push/Pull” Policy and Charging Rules

AF packets“Pi” Interface

Per subscriber R-P interface with IP QoS

Subscriber RABs

PCRF

AGW

Diameter Subsessions

Diameter Subsessions

1

2

3

1

2

3

1

2

3

3 Subscriber running identical applications from different handsets, clients, and locations

Application 2 has no AF.

PCRF and AGW have separate policies and gates for bearers and IP QoS..

IP QoS on R-P interface represents application rules e.g. “Silver subscriber get 512Kbs for Video”

e.g. Subscriber 1 and 2 have different IP QoS for application 3

But IP QoS may be smaller or greater than authorized RABs

PCRF and AGW may try to correlate bearer and IP QoS as part of the policy rules but correlation is not required.

PCRF can use information on bearers for admission control of IP QoS and vice-versa

• If Correlation of AF and Bearer are important, the operator can impose application-level event sequencing – i.e. client application logic ensures that push arrives before pull or vice-versa

AF MSPCRF PCRF AFMS Push must arrive at PCRF before Pull:

Push Policy:

If: IP_port is VIDEO and subscriber-tier is VIDEO-ENABLED

Then: Create gate

Else: Reject gate

Pull policy:

If Bearer_TFT is VIDEO subscriber has IP_Gate with port = VIDEO

Then: Create Gate

Else: Reject Gate

Push must arrive at PCRF After Pull:

Pull policy:

If Bearer_TFT is for VIDEO and subscriber-tier is VIDEO-ENABLED

Then: Create Gate

Else: Reject Gate

Push Policy:If: IP_port is for VIDEO and subscriber has a Bearer_ Gate with port = VIDEO

Then: Create gate

Else: Reject gate

Application-level Event Sequencing

Subscriber must have use an AF for Video

Subscriber must have a Video Bearer to use AF

UE-1

1. INVITE

UE-2

2. INVITE

4. Auth Request3. 183 Progress

13. RAN QoS Request

14. Auth Request

Bearer Establishment

Bearer Establishment

9. PRACK10. PRACK

16. RAN QoS Resp

12. 200 OK (prack)11. 200 OK (prack)

AF(P-CSCF)

PCRFAGW

8. 183 Progress (A1)

7. Auth Response

5. Re-Auth(create gates)

6. Re-Auth Resp

TxTy

15. Auth Resp

17. RAN QoS Request

20. RAN QoS Resp

18. Auth Request

19. Auth Resp

IP-QoS Gates created (closed)

21. UPDATE22. UPDATE

24. 200 OK (update)23. 200 OK (update)

RAN-QoS Gates created (opened)

RAN-QoS Gates created (opened)

Client rings(180 not shown)

Client answers25. 200 OK (invite)26. Auth Request

(Open Gates)

28. Re-Auth Resp

27. Re-Auth (open gates)

29. Auth Response30. 200 OK (invite)

31. ACK32. ACK

IP-QoS Gates are opened