- Overview
- Using the Graphical User Interface
- RADIUS Accounting
- Diameter
- Extensible Authentication Protocols
- Using Replication
- Using Identity Caching
- Using Prepaid Billing
- Using Cisco Prime Access Registrar Server Features
- Directing RADIUS Requests
- Using FastRules to Process Packet Flow
- Using LDAP
- Using Open Database Connectivity
- SIGTRAN-M3UA
- Using SNMP
- Backing Up the Database
- Diameter with EAP Support
- Diameter Server Startup Log
- Diameter Stack Level Messages
- Configuring Authentication and Authorization for Diameter
- Configuring the Diameter Application in PrimeAccessRegistrar
Diameter
Diameter is a networking protocol which is derived from RADIUS protocol. It is considered to be the next generation Authentication, Authorization, and Accounting (AAA) protocol. This is the other core protocol used in the IP Multimedia Subsystem (IMS) architecture for IMS Entities to exchange AAA related information. Cisco Prime Access Registrar (Prime Access Registrar) supports Diameter Applications based on the Diameter Base Protocol defined in RFC 6733.
Diameter is composed of a base protocol and a set of applications which allows it to extend its services to new access technologies. The base protocol provides basic mechanisms for reliable transport, message delivery, and error handling. Each application is defined by an application identifier and associated with commands. Each command is defined with mandatory Attribute Value Pairs (AVPs) and non-mandatory AVPs including vendor-specific AVPs.
The base protocol must be used in conjunction with a Diameter application. Each application relies on the services of the base protocol to support a specific type of network access.
The following is the list of applications supported by Prime Access Registrar:
- Diameter Network Access Server Application (NASREQ, RFC 4005)
- Diameter Base Accounting (RFC 6733)
- Diameter Extensible Authentication Protocol (EAP) Application (RFC 4072)
This chapter contains the following sections:
- Diameter with EAP Support
- Diameter Server Startup Log
- Diameter Stack Level Messages
- Configuring Authentication and Authorization for Diameter
- Configuring the Diameter Application in Prime Access Registrar
- Writing Diameter Application in Prime Access Registrar
- Translation Framework for Diameter
- TLS Support for Diameter
- Managing Diameter Sessions
- Blacklisting Support for Diameter Remote Server
- SCTP Multihoming Support for Diameter Client and Remote Server
- Diameter Multiple Proxy Support
- Diameter Overload Indication Conveyance Support for Diameter
Diameter with EAP Support
The Extensible Authentication Protocol (EAP), is an authentication framework which supports multiple authentication mechanisms. EAP may be used on dedicated links, switched circuits, and wired as well as wireless links. For more information on EAP support in Prime Access Registrar, see Chapter5, “Extensible Authentication Protocols”
Prime Access Registrar supports Diameter EAP application that carries EAP packets between a Network Access Server (NAS) working as an EAP Authenticator and a back-end authentication server. The Diameter EAP application is based on the Diameter Network Access Server Application [NASREQ] and is intended for environments similar to NASREQ.
In the Diameter EAP application, authentication occurs between the EAP client and its home Diameter server. This end-to-end authentication reduces the possibility for fraudulent authentication, such as replay and man-in-the-middle attacks. End-to-end authentication also provides a possibility for mutual authentication, which is not possible with PAP and CHAP in a roaming PPP environment.
This topic contains the following sections:
Advertising Application Support
Diameter nodes conforming to this specification must advertise support by including the Diameter EAP Application ID value of 5 in the Auth-Application-Id AVP of the Capabilities-Exchange-Request and Capabilities-Exchange-Answer command [BASE].
If the NAS receives a response with the Result-Code set to DIAMETER_APPLICATION_UNSUPPORTED [BASE], it indicates that the Diameter server in the home realm does not support EAP. If possible, the access device may attempt to negotiate another authentication protocol, such as PAP or CHAP. An access device must be cautious when determining whether a less secure authentication protocol will be used, since this could result from a downgrade attack.
Diameter EAP Conversation Flow
The EAP conversation between the authenticating peer and the access device begins with the initiation of EAP within a link layer, such as PPP [RFC1661] or IEEE 802.11i [IEEE-802.11i]. Once EAP has been initiated, the access device will typically send a Diameter-EAP- Request message with an empty EAP-Payload AVP to the Diameter server, signifying an EAP-Start. Prime Access Registrar routes the message to the Diameter EAP service through the rules and policy engine (and/or client, server and vendor scripting point) through which the packet is processed. The Diameter EAP Service forms a Diameter-EAP-Answer message containing an EAP-Payload AVP that includes an encapsulated EAP packet. The Result-Code AVP in the message will be set to DIAMETER_MULTI_ROUND_AUTH, signifying that a subsequent request is expected.
Figure 4-1 describes the Diameter EAP request flow.
Figure 4-1 Diameter EAP Request Flow
The access device issues the EAP-Request/Identity message to the EAP client, and forwards the EAP-Response/Identity packet, encapsulated within the EAP-Payload AVP, as a Diameter-EAP-Request to Prime Access Registrar as shown in Figure 4-2. This reduces the number of Diameter message round trips.
Figure 4-2 Diameter EAP Response Flow
The conversation continues until the Diameter server sends a Diameter-EAP-Answer with a Result-Code AVP indicating success or failure, and an optional EAP-Payload. The Result-Code AVP is used by the access device to determine whether service is to be provided to the EAP client or not. The access device must not rely on the contents of the optional EAP-Payload to determine whether service is to be provided or not.
Diameter Server Startup Log
When Prime Access Registrar starts, Diameter server also starts.
The log file shows the following:
Diameter Stack Level Messages
The following are the stack level messages that are exchanged between the diameter peers:
Capabilities Exchange Message
When Diameter peers establish a transport connection to Prime Access Registrar, they will exchange the Capabilities Exchange messages. This message allows the discovery of a peer's identity and its capabilities (protocol version number, supported Diameter applications, security mechanisms, etc.)
The log file shows the following:
Watchdog Message
The Device-Watchdog-Request and Device-Watchdog-Answer messages are used to proactively detect transport failures. Device Watchdog message time interval is configurable in Prime Access Registrar.
Disconnect Message
Disconnect messages are initiated when Diameter peers lose transport connection to Prime Access Registrar.
Configuring Authentication and Authorization for Diameter
This section describes how to configure Prime Access Registrar to perform authentication and authorization and how to configure a local service and userlist.
See for more information on Diameter client properties.
This section contains the following topics:
Configuring Local Authentication and Authorization
In Diameter, an AA-Request packet is a request for authentication and authorization. Authentication checks username and password credentials, while authorization typically involves returning the correct information to allow the service a user is authorized to have. Prime Access Registrar performs AA and returns the appropriate Diameter attributes in an AA-Answer packet.
For adding a Diameter peer in Prime Access Registrar, configure a new entry in the clients (including Policy and Charging Rules Functions (PCRF), Home Subscriber Servers (HSS), Mobility Management Entities (MME), Online Charging Systems (OCS), and others) and remote server object.
The following shows an example configuration for adding a Diameter peer (NAS/Client) in Prime Access Registrar.
Note
You should restart the Prime Access Registrar server if you change any Diameter specific configuration.
Configuring a Local Service and UserList
See for more information on how to configure a local service and user list.
The following messages are logged in the trace file at the time of authenticating a valid user:
The following messages are logged in the trace file at the time of authenticating an invalid user:
Configuring External Authentication Service
See for more information on how to configure external authentication service.
Configuring the Diameter Application in Prime Access Registrar
For proxying a diameter application message in Prime Access Registrar, ensure that you do the following:
- Configuring the Transport Management Properties
- Registering Applications IDs
- Configuring the Diameter Peers
- Configure the Diameter Service
Configuring the Transport Management Properties
You need to log into the aregcmd using the CLI interface and configure the Transport Management properties in the Radius/Advanced/Diameter/.
You need to set the Identity and AdvertisedHostName properties to IP Address or hostname of the machine in which Prime Access Registrar is installed.
The description for these properties is available at:
http://www.cisco.com/en/US/docs/net_mgmt/access_registrar/5.1/user/guide/objects.html#wp1145662
Note Prime Access Registrar can only listen to one port for diameter connections. In the above configuration, the port number is 3868. All of the diameter clients must use this port number to communicate with the Prime Access Registrar.
Registering Applications IDs
You need to register the applications IDs for which Prime Access Registrar needs to route the Diameter Messages.
Registering the Gy application to a diameter stack
To register the Gy application to a diameter stack,
Step 1 Move to the //localhost/Radius/Advanced/Diameter/General directory.
For description of these properties, see.
Step 2 Set the AuthApplicationIdList to list of colon separated values of Application Ids.
Configuring the Diameter Peers
You need to configure the Diameter Peers such as clients and servers in the /radius/clients and /radius/remoteservers directories. The following is an example for configuring a Diameter client:
The following is an example for configuring a Diameter remote server:
For description of these properties, see.
Note In order to resolve the hostnames and get the IP addresses, the Prime Access Registrar should either be configured with a DNS server IP, or the client's hostnames and IP addresses should be included in the /etc/hosts file.# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 Prime Access Registrar localhost.localdomain localhost
172.16.29.7 GGSN-Gy
::1 localhost6.localdomain6 localhost6
Configure the Diameter Service
To configure the Diameter Service to route the Diameter Messages,
Step 1 Add a Service of type diameter in /Radius/Services/.
Step 2 Configure the sticky properties.
Step 3 Add the peers to which Prime Access Registrar needs to load balance the diameter messages.
Step 4 Save the configuration details.
Step 5 Set DefaultAuthenticationService and DefaultAuthorizationService in /Radius directory.
Step 6 Restart thePrime Access Registrar server.
The following illustrates the diameter proxy service configuration which load balances the diameter messages to the remote peers.
Group-Based Load Balancing in Diameter Proxy Server Configuration
Prime Access Registrar allows you to create two or more groups of Diameter remote servers in a Diameter proxy service configuration. Each of these groups will have a unique set of remote servers, i.e. no two groups will share the same remote server.
The traffic between each of these groups is load-balanced in failover mode; while traffic between remote servers within the same group is load-balanced based on round-robin or failover mode depending on the existing Diameter configuration. The priority of each of the groups is set with the help of metrics.
The workflow for group-based load balancing is as given below:
1. Traffic from Prime Access Registrar to remote server, via Diameter proxy service, is directed through the first group, till Prime Access Registrar has active communication channel with at least one remote server belonging to the first group.
2. When Prime Access Registrar loses connectivity with all the remote servers in the first group, it directs the rest of the Diameter traffic towards remote servers belonging to the second group.
3. Within a group, the load-balancing logic is chosen based on the configuration:
a. If the load-balancing logic is configured to be round-robin, the traffic is distributed across all the active remote servers.
b. If the load-balancing logic is configured to be failover, the traffic is directed towards first priority remote server. When Prime Access Registrar loses connectivity with the first priority remote server, it directs the subsequent traffic towards the second priority remote server. The priority of the Diameter remote servers, in case of failover logic, is set with the help of metrics.
For more information about Diameter server group parameters, see GroupServers.
Following is a sample configuration of the Diameter group server:
Writing Diameter Application in Prime Access Registrar
Prime Access Registrar supports extensibility by allowing users to create new:
This section contains the following topics:
- Configuring rex script/service for Diameter
- Scripting in Diameter
- Diameter Environment Variables
- Sample rex script/service
- Traces/Logs
Configuring rex script/service for Diameter
To configure script/service for diameter using aregcmd:
Step 1 Add diameter AVPs in //localhost/Radius/Advanced/DiameterDictionary/DiameterAttributes other than Base stack AVPs.
Step 2 Write a rex script (C/C++) and add it in the scripting point or rex service.
Refer to Sample rex script/service.
Scripting in Diameter
Prime Access Registrar supports 'rex' scripts for Diameter protocol. The script can be configured only as the server incoming script. The commands available for scripting are restricted to 'get' and 'put' on the dictionaries. While setting a value to an attribute, the following convention needs to be followed "<type number>,<value>". For example, if a 'Class' attribute needs to be added to the response dictionary with value as "classvalue", then set it as follows in the script:
pResponse->put( pResponse, "Class", "1,classvalue", REX_REPLACE);
The following is the list of supported scripting types with the respective type numbers:
Setting response attributes via a script is the only mechanism to add authorization attributes for Diameter requests.
Diameter Environment Variables
This section lists the environment variables that you can use in scripts for Diameter messages.
Table 4-1 lists the Diameter Environment variables and descriptions.
Sample rex script/service
Traces/Logs
Translation Framework for Diameter
Prime Access Registrar supports translation of an incoming RADIUS request to a Diameter request and vice versa.
The following services are created to set up the translation framework:
- Radius-Diameter—For translation of incoming RADIUS request to Diameter equivalent and then the Diameter response to RADIUS equivalent.
- Diameter-Radius—For translation of incoming Diameter request to RADIUS equivalent and then the RADIUS response to Diameter equivalent.
For both the translation services, Prime Access Registrar uses the following scripting points to operate on the original packet and on the newly translated packet based on request and response mapping:
- PreRequestTranslationScript—To add/modify/delete incoming RADIUS/Diameter attribute values in the request before translation
- PostRequestTranslationScript—To add/modify/delete translated Diameter/RADIUS attributes in the request after translation
- PreResponseTranslationScript—To add/modify/delete Diameter/RADIUS attribute values in the response before translation
- PostResponseTranslationScript—To add/modify/delete RADIUS/Diameter attributes in the response after translation
RADIUS to Diameter translation comes with the 3GPP reverse authorization, if the property is set as True. In that case, the request command mapping must not be defined because the new diameter request is created from the radius request by the 3GPP reverse authorization service. When the diameter response is received from the diameter proxy service, it translates the Diameter response to RADIUS response based on the response mapping configuration and sends radius response to the client.
Prime Access Registrar supports CoA and PoD translation to Re-Auth-Request (RAR) / Abort-Session-Request (ASR), which is triggered directly to Diameter Client without any DRA. Prime Access Registrar sends the translated RAR/ASR packets to client, by configuring a parameter SendRAR-ASRToClient. You must also configure the Diameter client to which the packet needs to be sent using the host name of the client in the translation service.
Both these translation services create and maintain appropriate states (with the necessary identifiers, packet pointers, etc) to correlate Request to Response. The states will be cleared if present beyond the ‘Timeout’ property value and all the retries have been exhausted. You can configure the number of retries under Diameter-RemoteServers.
For more information about the translation parameters, see Simple Services.
CLI for RADIUS-Diameter Translation
Following is the CLI for RADIUS to Diameter translation:
CLI for Diameter-RADIUS Translation
Following is the CLI for Diameter to RADIUS translation:
TLS Support for Diameter
Prime Access Registrar supports Transport Level Security (TLS) mechanism for Diameter stack. The system provides an option to enable TLS for Diameter client and Diameter remote server. When the TLS option is disabled, communication is established directly using the transport layer without applying any encryption. The Diameter TLS feature uses the CiscoSSL libraries, which are available as part of the Prime Access Registrar package.
Following is the CLI configuration of a Diameter client with TLS support:
Following is the CLI configuration of a Diameter remote server with TLS support:
For descriptions of the TLS options, see the Network Resources section of Chapter2, “Using the Graphical User Interface”
Managing Diameter Sessions
Diameter provides two kinds of services namely authentication/authorization and accounting only (optional). Diameter sessions can be created when an authentication/authorization request comes from an access point or when an accounting start comes from an access point. When a Diameter client issues an authentication request, Prime Access Registrar sends the packet with a Session-Id AVP, which can be used to correlate a Diameter message with a user-session. When a Session Termination Request (STR) message is received from the Diameter client, Prime Access Registrar releases the sessions. Also Re-authentication requests must be mapped to the corresponding user session. In case of accounting packets, the session is created when the accounting start is received from the Diameter client. The session is deleted when the accounting stop message is received.
Prime Access Registrar creates a new session when it receives an authentication or accounting request packet from a Diameter client and when a user session is not already present. It allocates the resources for the particular session from the resource manager and stores the session in a session backing store. This session backing store is a file where session information is written. When a session termination message or an accounting stop message comes from the Diameter client, the session data is deleted from the backing store. Apart from this, Prime Access Registrar maintains the session state for every session it creates. Session cache will be supported for grouped AVPs.
For more information on session manager and its support for Diameter client, see SessionManagers.
Blacklisting Support for Diameter Remote Server
Prime Access Registrar supports blacklisting of IMSI or IP address values for Diameter remote servers.
You can choose to configure blacklisting as part of the outgoing script of a Diameter remote server with EAP-SIM or EAP-AKA service. For more information about blacklisting, see.
SCTP Multihoming Support for Diameter Client and Remote Server
Stream Control Transmission Protocol (SCTP) is an IP transport protocol that supports data exchange between exactly two endpoints. Multihoming feature of SCTP provides the ability for a single SCTP endpoint to support multiple IP addresses. With this feature, each of the two endpoints during an SCTP association can specify multiple points of attachment. Each endpoint will be able to receive messages from any of the addresses associated with the other endpoint. With the use of multiple interfaces, data can be sent to alternate addresses when failures occur and thus Prime Access Registrar runs successfully even during network failures.
Prime Access Registrar provides SCTP multihoming support for Diameter client and remote server. With this feature, you can configure multiple source and destination addresses on the Diameter client and remote server.
Note When you use Prime Access Registrar with CentOS, ensure that you configure the Diameter SCTP client and remote servers with different source ports in Prime Access Registrar.
The following shows an example configuration of Diameter remote server with multiple source and destination addresses:
The following shows an example configuration of Diameter client with multiple source and destination addresses:
For details of the SCTP parameters, see SCTPParameters Section.
Diameter Multiple Proxy Support
Prime Access Registrar supports Diameter client configurations in multiple proxy mode. As part of this functionality, client-based Diameter connections can be established from multiple peers with the same IP address but with different source ports and origin-hosts.
The Origin-Host AVP is of type Diameter Identity and must be present in all Diameter messages. This AVP is unique to a host and indicates the endpoint that originated the Diameter message.
When Prime Access Registrar gets a connection from any peer, initially Capabilities Exchange messages (CER-CEA) are exchanged with the client. These messages allow the discovery of peer's identity and its capabilities.
After successful Capabilities exchange with the client, Prime Access Registrar selects the exact client object from the CLI, based on the Origin-Host in CER packet.
A new attribute EnableMultiProxyMode is added to the Diameter client configuration to support this feature. To use this feature, you must configure at least two clients in multiple proxy mode, with the same source IP.
- For all the clients configured in multiple proxy mode, the host name must be some name and not an IP address.
- The current implementation of this feature supports only Diameter TCP and TLS connections. It does not support Diameter Routing Agent (DRA) and SCTP connections.
- The maximum number of clients that can be configured in multiple proxy mode with the same IP is 15.
- All the clients configured in multiple proxy mode must have one and the same connection type; either TCP or TLS.
The following CLIs are sample configurations of two clients with same IP Address. host-1 and host-2 mentioned in the following samples are host names referring to the same IP address.
Diameter Overload Indication Conveyance Support for Diameter
Diameter Overload Indication Conveyance (DOIC) is a set of standards for supporting dynamic overload controls between Diameter servers and Diameter clients. This allows Diameter servers to send overload reports to Diameter clients requesting reduction in traffic (throttling) for any duration of time.
Currently Prime Access Registrar has an application-wide throttling mechanism, in which the application starts dropping packets when the incoming request rate is growing above the configured value. Here all the packets are given equal priority. It is not possible to throttle any specific packets.
With the DOIC feature, under active overload conditions, it is possible to throttle (forward, divert, or drop) the packets based on configured priority levels.
There are 2 perspectives when considering DOIC in Prime Access Registrar:
- Prime Access Registrar as reacting node (Client)—when there is a communication between Prime Access Registrar and remote server.
- Prime Access Registrar as reporting node (Server)—When there is a communication between client and Prime Access Registrar.
Prime Access Registrar as Reacting Node
- When Prime Access Registrar pushes traffic to HSS, Prime Access Registrar acts as client and HSS as remote server.
- When both Prime Access Registrar and HSS support DOIC, they exchange capabilities in OC-Supported-Features AVP.
- When HSS detects that it is overloaded, it starts sending OC-OLR (Overload Report) AVP in all the response messages; OC-OLR AVP contains the following information about the active overload condition:
– Overload Reduction Percentage—Indicates the percentage of traffic that the reacting node should throttle.
– Validity Duration—Indicates the time of expiry of the overload report.
– Report Type—Indicates the type of overload report, which is Host_Type.
– Sequence Number—Indicates a number, which is incremented every time when any of the sub-AVPs in OC-OLR grouped AVP is modified.
- When Prime Access Registrar receives OC-OLR AVP, it understands that the HSS is overloaded and starts throttling the packets till the specified validity duration. Throttling includes forwarding, diverting, or dropping packets based on configured priority levels.
- Along with throttling, Prime Access Registrar also checks if the outgoing traffic to HSS is reduced by the overload reduction percentage value received in the OC-OLR. After reaching the percentage indicated, further incoming packets will be processed as usual.
Prime Access Registrar as Reporting Node
- When both Prime Access Registrar and the Diameter client support DOIC, they exchange capabilities in OC-Supported-Features AVP.
- When Prime Access Registrar reaches 75% of the configured value of MaxinumNumberOfDiameterPackets, it becomes overloaded.
- When Prime Access Registrar detects that it is overloaded, it starts sending OC-OLR grouped AVP in all the response messages. This OC-OLR AVP contains information about the active overload condition such as overload reduction percentage, validity duration, report type, and sequence number.
Sample CLI for the DOIC feature
The Priority directories are static. The sub directories in it are added dynamically.
Other than forward and divert, the remaining requests that contribute to overload percentage reduction are dropped.
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