Diameter Applications Design Guidelines Document (draft-fajardo-dime-app-design-guide-00.txt)

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Diameter Applications Design Guidelines
Document (draft-fajardo-dime-app-design-guide-00
.txt)
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• Overview
• Purpose
• To aid Diameter application designers on how to
  extend Diameter
• Describes some of the possible tradeoffs
  encountered when designing applications
• Clarify the extensibility rules in RFC3588
• The document is NOT
• Intended to replace or change existing
  extensibility rules
• Intended to add new rules

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• Rules of Diameter Extensibility
• How to Extend Diameter Allocation of
  Application Id
• Creation of new mandatory AVP(s)
• Creation of new command(s)
• When to Define New Applications
• General Rule Re-use AVPs and commands as much as
  possible
• When adding new mandatory AVPs or AVP Values
• Does this new AVP or AVP value significantly
  change the semantics of the application ?
• Can be difficult to determine what is a
  significant change
• Avoid use optional AVPs to add new semantics for
  existing applications
• Think about backward compatibility, use well
  known versioning schemes instead of adding new
  optional AVPs
• When message roundtrip changes
• When a new command is required

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• Design Considerations
• Common Tradeoffs
• Use of a single applications can lead to
  monolithic architectures
• Can be similar to a RADIUS model
• Complex management for distributed architectures
• Co-relation of application services, i.e.
  separation of authentication and authorization
• Increased traffic and implementation footprint
• Accounting support
• Base protocol accounting, split model
• ACR/ACA using app-id of the application, coupled
  model
• Generic extensions
• Common to any applications, i.e. redundancy,
  auditing, congestion control etc.
• Typically should not require a new application
  if
• Peer-to-peer
• End-to-end but can be piggybacked to application
  traffic, i.e. Proxy-Info AVP
• Application Id used in base protocol session
  messages
• Application level messages RAR/RAA, STR/STA and
  ASR/ASA should use the application id of the
  application
• Server initiated request and Diameter user
  sessions