DIAMETER
From Wikipedia, the free encyclopedia
- For the geometric term, see Diameter
DIAMETER is an AAA protocol (Authentication, Authorization and Accounting) succeeding its predecessor RADIUS.
Contents |
[edit] Upgrade from RADIUS
The name is a pun on the RADIUS protocol, which is the predecessor (a diameter is twice the radius). Diameter is not directly backwards compatible, but provides an upgrade path for RADIUS. The main differences are :
- it uses reliable transport protocols (TCP or SCTP, not UDP)
- it can use transport level security (IPsec or TLS)
- it has transition support for RADIUS
- it has larger address space for AVPs (Attribute Value Pairs) and identifiers (32-bit instead of 8-bit)
- it is a client-server protocol, with exception of supporting some server-initiated messages as well
- both stateful and stateless models can be used
- it has dynamic discovery of peers (using DNS SRV and NAPTR)
- it has capability negotiation
- it supports application layer acknowledgements, defines failover methods and statemachines (RFC 3539)
- it has error notification
- it has better roaming support
- it is more easily extended; new commands and attributes can be defined
- it is aligned on 32 bit boundaries
- it has basic support for user-sessions and accounting
[edit] Protocol description
The Diameter Base Protocol is defined by RFC 3588, and defines the minimum requirements for an AAA protocol. Diameter Applications can extend the base protocol, by adding new commands and/or attributes. An application is not a program, but a protocol based on Diameter. Diameter security is provided by IPSEC or TLS, both well-regarded protocols.
[edit] Packet format
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Version | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | command flags | Command-Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Application-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Hop-by-Hop Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | End-to-End Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | AVPs | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
[edit] Commands
Each command is assigned a command code, which is used for both requests and answers.
Command-Name | Abbr. | Code |
---|---|---|
Abort-Session-Request | ASR | 274 |
Abort-Session-Answer | ASA | 274 |
Accounting-Request | ACR | 271 |
Accounting-Answer | ACA | 271 |
Capabilities-Exchange-Request | CER | 257 |
Capabilities-Exchange-Answer | CEA | 257 |
Device-Watchdog-Request | DWR | 280 |
Device-Watchdog-Answer | DWA | 280 |
Disconnect-Peer-Request | DPR | 282 |
Disconnect-Peer-Answer | DPA | 282 |
Re-Auth-Request | RAR | 258 |
Re-Auth-Answer | RAA | 258 |
Session-Termination-Request | STR | 275 |
Session-Termination-Answer | STA | 275 |
[edit] Attribute-Value Pairs (AVP)
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | AVP Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |V M P r r r r r| AVP Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Vendor-ID (opt) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Data ... +-+-+-+-+-+-+-+-+
Attribute-Name | Code | Data Type |
---|---|---|
Acct-Interim-Interval | 85 | Unsigned32 |
Accounting-Realtime-Required | 483 | Enumerated |
Acct-Multi-Session-Id | 50 | UTF8String |
Accounting-Record-Number | 485 | Unsigned32 |
Accounting-Record-Type | 480 | Enumerated |
Accounting-Session-Id | 44 | OctetString |
Accounting-Sub-Session-Id | 287 | Unsigned64 |
Acct-Application-Id | 259 | Unsigned32 |
Auth-Application-Id | 258 | Unsigned32 |
Auth-Request-Type | 274 | Enumerated |
Authorization-Lifetime | 291 | Unsigned32 |
Auth-Grace-Period | 276 | Unsigned32 |
Auth-Session-State | 277 | Enumerated |
Re-Auth-Request-Type | 285 | Enumerated |
Class | 25 | OctetString |
Destination-Host | 293 | DiamIdent |
Destination-Realm | 283 | DiamIdent |
Disconnect-Cause | 273 | Enumerated |
E2E-Sequence | 300 | Grouped |
Error-Message | 281 | UTF8String |
Error-Reporting-Host | 294 | DiamIdent |
Event-Timestamp | 55 | Time |
Experimental-Result | 297 | Grouped |
Experimental-Result-Code | 298 | Unsigned32 |
Failed-AVP | 279 | Grouped |
Firmware-Revision | 267 | Unsigned32 |
Host-IP-Address | 257 | Address |
Inband-Security-Id | 299 | Unsigned32 |
Multi-Round-Time-Out | 272 | Unsigned32 |
Origin-Host | 264 | DiamIdent |
Origin-Realm | 296 | DiamIdent |
Origin-State-Id | 278 | Unsigned32 |
Product-Name | 269 | UTF8String |
Proxy-Host | 280 | DiamIdent |
Proxy-Info | 284 | Grouped |
Proxy-State | 33 | OctetString |
Redirect-Host | 292 | DiamURI |
Redirect-Host-Usage | 261 | Enumerated |
Redirect-Max-Cache-Time | 262 | Unsigned32 |
Result-Code | 268 | Unsigned32 |
Route-Record | 282 | DiamIdent |
Session-Id | 263 | UTF8String |
Session-Timeout | 27 | Unsigned32 |
Session-Binding | 270 | Unsigned32 |
Session-Server-Failover | 271 | Enumerated |
Supported-Vendor-Id | 265 | Unsigned32 |
Termination-Cause | 295 | Enumerated |
User-Name | 1 | UTF8String |
Vendor-Id | 266 | Unsigned32 |
Vendor-Specific-Application-Id | 260 | Grouped |
[edit] State machines
[edit] Message flows
[edit] Applications
A Diameter Application isn't a software application, but a protocol based on the DIAMETER Base protocol (defined in 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 doesn't 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
[edit] External links
- http://www.opendiameter.org/
- http://www.cisco.com/en/US/products/ps6638/products_data_sheet09186a00804fe332.html Cisco page outlining differences between RADIUS and DIAMETER
- http://www.csg.uzh.ch/staff/morariu/opendiameter/ - Debian Packages for OpenDiameter
- https://jdiameter.dev.java.net/ - Diameter Base Protocols written in Java