Diameter Signaling Router Functions

The Diameter Signaling Router (DSR) provides the following functions:

Base Diameter Relay Agent: The DSR uses a Diameter Relay Agent to forward a message to the appropriate destination based on the information contained in the message.
Core Routing and Load Balancing: The DSR creates a centralized Diameter signaling core that handles routing, traffic management, and load balancing tasks; and provides a single interconnect point to other networks.
The IP Front End (IPFE) can run in a DSR system to distribute traffic across connections.
DNS A and AAAA support: The DSR supports resolving host names using DNS A and AAAA queries based on the configured Peer IP address of the connection when the peer IP address is not provisioned.
Diameter Transport Function: The Diameter Transport Function is responsible for managing the transport connections only on a single MP and relies on the Diameter Routing Function to perform distributed processing.
- Diameter Connection management: Reporting of Diameter Connection status changes.
  The DSR supports up to 64 transport Connections per Peer Node, and up to 32 Local Nodes.
  
  The DSR supports multiple Diameter Connections to any Peer Node and multiple Peer Nodes.
- SCTP and TCP transport protocols: The DSR supports both Stream Control Transmission Protocol (SCTP uni-homing and multi-homing) and Transmission Control Protocol (TCP) based transport Connections.
- Message Processing: Processing of Diameter Peer-to-Peer messages (CER/CEA, DWR/DWA, DPR/DPA), and delivery of Diameter Request and Answer messages from and to Diameter Peers and the Diameter Routing Function.
Diameter Routing Function:
- Routing of Diameter Request and Answer messages to and from Diameter Peers (through the Diameter Transport Function) and DSR Applications.
  - Peer Routing Rules: The DSR provides the ability to configure up to 1000 Peer Routing Rules, in up to 100 Peer Route Tables, that define where to route a Diameter message to an upstream Peer based upon Diameter message content.
  - Application Routing Rules: The DSR provides the ability to configure up to 1000 Application Routing Rules, in up to 100 Application Route Tables, that are used by the Diameter Routing Function to determine whether a received Diameter message will be routed to a specific DSR Application or routed to a Diameter Peer in the network. The Application Routing Rules are rules based upon the Diameter message Application ID, Command-Code, Destination-Realm/Host, and Origin-Realm/Host.
  - Application Chaining: Application Routing Rules can be configured to allow more than one DSR Application to process the same Diameter Request message. (The same message is not usually processed more than once by the same Application.)
  - Processing of Diameter Connection status from the Diameter Transport Function and status from DSR Applications for maintaining dynamic routing configuration data.
  - Message Rerouting: A Diameter Relay Agent is responsible for making sure that Request messages are successfully delivered, and to choose an alternate route if failures are encountered.
    - Alternate Implicit Routing: Instead of a message being routed directly to an unavailable Peer Node, the message is routed on an alternate implicit route that is chosen from a Route List that has been configured for the Peer Node.
    - Reroute on Answer: The DSR supports alternate routing of a Request message when an Answer response is received with a configured error code.
- Topology Hiding: Trusted Network Lists, Protected Networks, and Configuration Sets for specific Diameter applications or any Diameter application are used for Diameter Topology Hiding functions.
- Shared Traffic Throttle Groups: Shows all TTGs defined as shared across the diameter routing network. TTGs can be shared between DSR Nodes in the same network managed by a NOAM. Thus, each TTG is uniquely identified by its DSR Node.
- Diameter Message Copy: Copying of messages to a DAS can be triggered by Peer Routing Rules, Diameter Mediation, or a DSR Application. Message Copy Configuration Sets provide the data required Diameter Message Copy functions.
- Next Generation Network Priority Service (NGN-PS) that allows National Security/Emergency Preparedness (NS/EP) users to make priority calls/sessions using public networks.
Bulk Import and Export: The DSR provides functions for exporting some or all of the Diameter, Diameter Common, IPFE, MAP-Diameter IWF, and DSR Application configuration data from an NOAM or SOAM to a CSV file, editing the file, and importing the edited file for inserting new configuration data, updating existing data, or deleting data on a local OAM, as well as PCA. Exports can be scheduled periodically for specified configuration data.
Virtualization on Servers: Virtualization defines and executes virtual machines to allow multiple functional components of the DSR to be deployed on a single Server, including TVOE, PM&C, SOAM, NOAM, DA-MP, IPFE, SDS (SOAM and NOAM), PCA (including SBR), and SS7 MP.
Capacity and Congestion Status and Control: Functions are provided for performing Connection capacity status and control, ingress message MPS control, and egress message throttling; and message processing, Connection, DSR Application, and DA-MP congestion status.
Diameter Mediation: The DSR provides configuration and application of rules that modify message processing behavior when conditions are met at specified trigger points in the message processing.
Diameter Intelligence Hub: The Diameter Intelligence Hub (DIH) provides the ability to troubleshoot Diameter transactions.
Integrated Diameter Intelligence Hub: The Integrated Diameter Intelligence Hub (IDIH) provides the ability to troubleshoot Diameter transactions.
DSR Switchover: The DSR servers operate in redundancy mode and support automatic failover to the standby server if the active server fails. Automatic failover does not require manual intervention, but is restricted to NOAM, SOAM, active/standby DA-MPs, and SBRs.
IPsec Support: The DSR supports transporting messages over Internet Protocol security (IPsec) secure Connections.
IPv4 and IPv6 Support: The DSR supports IPv6 and IPv4 IP address formats.
RADIUS Message Routing: The DSR supports RADIUS message routing by my means of a RADIUS Transport function (similar to the Diameter Transport Function) that supports the UDP (User Datagram Protocol) transport protocol. The existing Diameter Routing Function is used with minimal changes for routing RADIUS messages by converting incoming RADIUS messages to Diameter before invoking the Diameter Routing Function, and then converting Diameter messages back to RADIUS before forwarding to RADIUS peers.
AVP Removal: DSR supports the ability to remove AVPs from messages upon receipt from a Peer Node and to remove AVPs from messages upon forwarding to a Peer Node via an AVP Removal List that identifies a list of AVPs that must be removed.
Static ETR Throttling: Static ETR Throttling allows the operator to limit the rate of transactions that are forwarded to a particular Peer Node which are addressed to a particular Diameter Application ID. For each (Peer Node, Application ID) ordered pair that you want to throttle, create a Traffic Throttle Point (TTP) attribute and assign it a Maximum ETR value.
Peer Node reported congestion (DOIC): Supports the ability to modify the rate of transactions forwarded to a Peer Node based upon Diameter Overload Requests (OLRs) it receives in Answer responses from the Peer Node.
Dynamic Peer Discovery: Peer Discovery (also know as Dynamic Peer Discovery [DPD]) allows the user to discover remote hosts within user-defined Realms and to configure all required elements for successful routing of diameter traffic between the signaling router and those remote hosts. This configuration is dynamic and performs the configuration at the time the routing elements are created.
MAP Diameter-IWF: Allows the DSR to support bi-directional interworking between Diameter and SS7-MAP messages. This functionality is carried out by two applications: DM-IWF and MD-IWF.