RADIUS/Diameter Protocol Interactions This section describes some basic guidelines that servers acting as
AAA Translation Agents may use. A complete description of all the
differences between RADIUS and Diameter is beyond the scope of this
section and document. Note that this document does not restrict
implementations from creating additional translation methods, as long
as the translation function doesn't violate the RADIUS or the
Diameter protocols.
Although the Diameter protocol is in many ways a superset of RADIUS
functions, a number of RADIUS representations are not allowed, so
that new capabilities can be used without the old problems.
There are primarily two different situations that must be handled:
one in which a RADIUS request is received that must be forwarded as a
Diameter request, and another in which the inverse is true. RADIUS
does not support a peer-to-peer architecture, and server-initiated
operations are generally not supported. See [RADDynAuth] for an
alternative.
Some RADIUS attributes are encrypted. RADIUS security and encryption
techniques are applied on a hop-per-hop basis. A Diameter agent will
have to decrypt RADIUS attribute data entering the Diameter system,
and if that information is forwarded, the agent MUST secure it by
using Diameter specific techniques.
Note that this section uses the two terms, "AVP" and "attribute", in
a concise and specific manner. The former is used to signify a
Diameter AVP, and the latter to signify a RADIUS attribute.
9.1. RADIUS Request Forwarded as Diameter Request
This section describes the actions that should be taken when a
Translation Agent receives a RADIUS message to be translated to a
Diameter message.
Note that RADIUS servers are assumed to be stateless. It is also
quite possible for the RADIUS messages that comprise the session
(i.e., authentication and accounting messages) to be handled by
different Translation Agents in the proxy network. Therefore, a
RADIUS/Diameter Translation Agent SHOULD NOT be assumed to have an
When a Translation Agent receives a RADIUS message, the following
steps should be taken:
- If a Message-Authenticator attribute is present, the value MUST
be checked but not included in the Diameter message. If it is
incorrect, the RADIUS message should be silently discarded.
The gateway system SHOULD generate and include a Message-
Authenticator in returned RADIUS responses.
- The transport address of the sender MUST be checked against the
NAS identifying attributes. See the description of NAS-
Identifier and NAS-IP-Address below.
- The Translation Agent must maintain transaction state
information relevant to the RADIUS request, such as the
Identifier field in the RADIUS header, any existing RADIUS
Proxy-State attribute, and the source IP address and port
number of the UDP packet. These may be maintained locally in a
state table or saved in a Proxy-Info AVP group. A Diameter
Session-Id AVP value must be created using a session state
mapping mechanism.
- If the RADIUS request contained a State attribute and the
prefix of the data is "Diameter/", the data following the
prefix contains the Diameter Origin-Host/Origin-Realm/Session-
Id. If no such attributes are present and the RADIUS command
is an Access-Request, a new Session-Id is created. The
Session-Id is included in the Session-Id AVP.
- The Diameter Origin-Host and Origin-Realm AVPs MUST be created
and added by using the information from an FQDN corresponding
to the NAS-IP-Address attribute (preferred if available),
and/or to the NAS-Identifier attribute. (Note that the RADIUS
NAS-Identifier is not required to be an FQDN.)
- The response MUST have an Origin-AAA-Protocol AVP added,
indicating the protocol of origin of the message.
- The Proxy-Info group SHOULD be added, with the local server's
identity specified in the Proxy-Host AVP. This should ensure
that the response is returned to this system.
- The Destination-Realm AVP is created from the information found
in the RADIUS User-Name attribute.
- If the RADIUS User-Password attribute is present, the password
must be unencrypted by using the link's RADIUS shared secret.
The unencrypted value must be forwarded in a User-Password AVP
using Diameter security.
- If the RADIUS CHAP-Password attribute is present, the Ident and
Data portion of the attribute are used to create the CHAP-Auth
grouped AVP.
- If the RADIUS message contains an address attribute, it MUST be
converted to the appropriate Diameter AVP and type.
- If the RADIUS message contains Tunnel information [RADTunnels],
the attributes or tagged groups should each be converted to a
Diameter Tunneling Grouped AVP set. If the tunnel information
contains a Tunnel-Password attribute, the RADIUS encryption
must be resolved, and the password forwarded, by using Diameter
security methods.
- If the RADIUS message received is an Accounting-Request, the
Acct-Status-Type attribute value must be converted to a
Accounting-Record-Type AVP value. If the Acct-Status-Type
attribute value is STOP, the local server MUST issue a
Session-Termination-Request message once the Diameter
Accounting-Answer message has been received.
- If the Accounting message contains an Acct-Termination-Cause
attribute, it should be translated to the equivalent
Termination-Cause AVP value. (see below)
- If the RADIUS message contains the Accounting-Input-Octets,
Accounting-Input-Packets, Accounting-Output-Octets, or
Accounting-Output-Packets, these attributes must be converted
to the Diameter equivalents. Further, if the Acct-Input-
Gigawords or Acct-Output-Gigawords attributes are present,
these must be used to properly compute the Diameter accounting
AVPs.
The corresponding Diameter response is always guaranteed to be
received by the same Translation Agent that translated the original
request, due to the contents of the Proxy-Info AVP group in the
Diameter request. The following steps are applied to the response
message during the Diameter-to-RADIUS translation:
- If the Diameter Command-Code is set to AA-Answer and the
Result-Code AVP is set to DIAMETER_MULTI_ROUND_AUTH, the
gateway must send a RADIUS Access-Challenge. This must have
encapsulated in the RADIUS State attribute, with the prefix
"Diameter/", concatenated in the above order separated with "/"
characters, in UTF-8 [UTF-8]. This is necessary to ensure that
the Translation Agent receiving the subsequent RADIUS Access-
Request will have access to the Session Identifier and be able
to set the Destination-Host to the correct value. If the
Multi-Round-Time-Out AVP is present, the value of the AVP MUST
be inserted in the RADIUS Session-Timeout AVP.
- If the Command-Code is set to AA-Answer, the Diameter Session-
Id AVP is saved in a new RADIUS Class attribute whose format
consists of the string "Diameter/" followed by the Diameter
Session Identifier. This will ensure that the subsequent
Accounting messages, which could be received by any Translation
Agent, would have access to the original Diameter Session
Identifier.
- If a Proxy-State attribute was present in the RADIUS request,
the same attribute is added in the response. This information
may be found in the Proxy-Info AVP group, or in a local state
table.
- If state information regarding the RADIUS request was saved in
a Proxy-Info AVP or local state table, the RADIUS Identifier
and UDP IP Address and port number are extracted and used in
issuing the RADIUS reply.
When translating a Diameter AA-Answer (with successful result code)
to RADIUS Access-Accept that contains a Session-Timeout or
Authorization-Lifetime AVP, take the following steps:
- If the Diameter message contains a Session-Timeout AVP but no
Authorization-Lifetime AVP, translate it to a Session-Timeout
attribute (not a Termination-Action).
- If the Diameter message contains an Authorization-Lifetime AVP
but no Session-Timeout AVP, translate it to a Session-Timeout
attribute and a Termination-Action set to AA-REQUEST. (Remove
Authorization-Lifetime and Re-Auth-Request-Type.)
- If the Diameter message has both, the Session-Timeout must be
greater than or equal to the Authorization-Lifetime (required
by [BASE]). Translate it to a Session-Timeout value (with
value from Authorization-Lifetime AVP, the smaller one) and
with the Termination-Action set to AA-REQUEST. (Remove the
Authorization-Lifetime and Re-Auth-Request-Type.) the Origin-Host, Origin-Realm, and Diameter Session-Id AVPs
accurate track on session-state information.
9.1.1. RADIUS Dynamic Authorization Considerations
A Diameter/RADIUS gateway may communicate with a server that
implements RADIUS Dynamic Authorization [RADDynAuth]. If the server
supports these functions, it MUST be listening on the assigned port
and would receive RADIUS CoA-Request and Disconnect-Request messages.
These can be mapped into the Diameter Re-Auth-Request (RAR) and
Abort-Session-Request (ASR) message exchanges, respectively [BASE].
If the [RADDynAuth] is not supported, the port would not be active
and the RADIUS server would receive an ICMP Port Unreachable
indication. Alternatively, if the messages are received but with an
inappropriate Service-Type, the gateway can respond with the
appropriate NAK message and an Error-Cause attribute with the value
of 405, "Unsupported Service".
The RADIUS CoA-Request and Disconnect-Request messages will not
contain a Diameter Session-Id. Diameter requires that this value
match an active session context. The gateway MUST have a session Id
cache (or other means) to identify the sessions these functions
pertain to. If unable to identify the session, the gateway (or NAS)
should return an Error-Cause value 503, "Session Context Not Found".
The RADIUS CoA-Request message only supports a change of
authorization attributes, and the received CoA-Request SHOULD include
a Service-Type of "Authorize-Only". This indicates an extended
exchange request by the rules given in [RADDynAuth] section 3.2, note
6. This is the only type of exchange supported by Diameter [BASE].
For the CoA-Request, the translated RAR message will have a Re-Auth-
Type of AUTHORIZE_ONLY. The returned RAA will be translated into a
CoA-NAK with Error-Cause "Request Initiated". The gateway's Diameter
client SHOULD also start a reauthorization sequence by sending an AAR
message, which will be translated into an Access-Request message.
The RADIUS server will use the Access-Accept (or Access-Reject)
message to convey the new authorization attributes, which the gateway
will pass back in an AAA message.
Any attributes included in the COA-Request or Access-Accept message
are to be considered mandatory in Diameter. If they cannot be
supported, they MUST result in an error message return to the RADIUS
server, with an Error-Cause of "Unsupported Attribute". The Diameter
NAS will attempt to apply all the attributes supplied in the AA
message to the session.
A RADIUS Disconnect-Request message received by the gateway would be
translated to a Diameter Abort-Session-Request (ASR) message [BASE].
The results will be returned by the Diameter client in an AbortSession-Answer (ASA) message. A success indication would translate
to a RADIUS Disconnect-ACK, and a failure would generate a
Disconnect-NAK.
9.2. Diameter Request Forwarded as RADIUS Request
When a server receives a Diameter request to be forwarded to a RADIUS
entity, the following are examples of the steps that may be taken:
- The Origin-Host AVP's value is inserted into the NAS-Identifier
attribute.
- The following information MUST be present in the corresponding
Diameter response and therefore MUST be saved, either in a
local state table or encoded in a RADIUS Proxy-State attribute:
1. Origin-Host AVP
2. Session-Id AVP
3. Proxy-Info AVP
4. Any other AVP that MUST be present in the response and
has no corresponding RADIUS attribute.
- If the CHAP-Auth AVP is present, the grouped AVPs are used to
create the RADIUS CHAP-Password attribute data.
- If the User-Password AVP is present, the data should be
encrypted and forwarded by using RADIUS rules. The same is
true for any other RADIUS-encrypted attribute values.
- AVPs of the type Address must be translated to the
corresponding RADIUS attribute.
- If the Accounting-Input-Octets, Accounting-Input-Packets,
Accounting-Output-Octets, or Accounting-Output-Packets AVPs are
present, they must be translated to the corresponding RADIUS
attributes. If the value of the Diameter AVPs do not fit
within a 32-bit RADIUS attribute, the RADIUS Acct-Input-
Gigawords and Acct-Output-Gigawords must be used.
- If the RADIUS link supports the Message-Authenticator attribute
[RADIUSExt], it SHOULD be generated and added to the request.
When the corresponding response is received by the Translation Agent,
which is guaranteed in the RADIUS protocol, the following steps may
be taken:
- If the RADIUS code is set to Access-Challenge, a Diameter AA-
Answer message is created with the Result-Code set to
DIAMETER_MULTI_ROUND_AUTH. If the Session-Timeout AVP is
present in the RADIUS message, its value is inserted into the
Multi-Round-Time-Out AVP.
- If a Proxy-State attribute is present, extract the encoded
information; otherwise, retrieve the original Proxy-Info AVP
group information from the local state table.
- The response's Origin-Host information is created from the FQDN
of the RADIUS message's source IP address. The same FQDN is
also stored to a Route-Record AVP.
- The response's Destination-Host AVP is copied from the saved
request's Origin-Host information.
- The Session-Id information can be recovered from local state,
or from the constructed State or Proxy-State attribute, as
above.
- If a Proxy-Info AVP was present in the request, the same AVP
MUST be added to the response.
- If the RADIUS State attributes are present, they must be
present in the Diameter response, minus those added by the
gateway.
- Any other AVPs that were saved at request time, and that MUST
be present in the response, are added to the message.
When translating a RADIUS Access-Accept to Diameter AA-Answer that
contains a Session-Timeout attribute, do the following:
- If the RADIUS message contains a Session-Timeout attribute and
a Termination-Action attribute set to DEFAULT (or no
Termination-Action attribute at all), translate it to AA-Answer
with a Session-Timeout AVP and remove the Termination-Action
attribute.
- If the RADIUS message contains a Session-Timeout attribute and
a Termination-Action attribute set to AA-REQUEST, translate it
to AA-Answer with Authorization-Lifetime AVP and with Re-Auth-
Request-Type set to AUTHORIZE_AUTHENTICATE and remove the
Session-Timeout attribute.
9.2.1. RADIUS Dynamic Authorization Considerations
A RADIUS/Diameter gateway communicating with a RADIUS client that
implements RADIUS Dynamic Authorization [RADDynAuth] may translate
Diameter Re-Auth-Request (RAR) messages and Abort-Session-Request
(ASR) messages [BASE] into RADIUS CoA-Request and Disconnect-Request
messages respectively.
If the RADIUS client does not support the capability, the gateway
will receive an ICMP Port Unreachable indication when it transmits
the RADIUS message. Even if the NAS supports [RADDynAuth], it may
not support the Service-Type in the request message. In this case it
will respond with a NAK message and (optionally) an Error-Cause
attribute with value 405, "Unsupported Service". If the gateway
encounters these error conditions, or if it does not support
[RADDynAuth], it sends a Diameter Answer message with an Result-Code
AVP of "DIAMETER_COMMAND_UNSUPPORTED" to the AAA server.
When encoding the RADIUS messages, the gateway MUST include the
Diameter Session-ID in the RADIUS State attribute value, as mentioned
above. The RADIUS client should return it in the response.
A Diameter Re-Auth-Request (RAR) message [BASE] received by the
gateway will be translated into a RADIUS CoA-Request and sent to the
RADIUS client. The RADIUS client should respond with a CoA-ACK or
CoA-NAK message, which the gateway should translate into a Re-Auth-
Answer (RAA) message.
If the gateway receives a RADIUS CoA-NAK response containing a
Service-Type Attribute with value "Authorize Only" and an Error-Cause
Attribute with value "Request Initiated", this indicates an extended
exchange request per [RADDynAuth] section 3.2, note 6.
The response is translated to a Diameter Re-Auth-Answer (RAA) with a
Result-Code AVP of "DIAMETER_LIMITED_SUCCESS" sent to the AAA server.
Subsequently, the gateway should receive a RADIUS Access-Request from
the NAS, with a Service-Type of "Authorize Only". This is translated
into a Diameter AA-Request with an Auth-Request-Type AVP of
AUTHORIZE_ONLY and sent to the AAA server. The AAA server will then
reply with a Diameter AA-Answer, which is translated into a RADIUS
Access-Accept or Access-Reject, depending on the value of the
Result-Code AVP.
A Diameter Abort-Session-Request (ASR) message [BASE] received by the
gateway will be translated into a RADIUS Disconnect-Request and sent
to the RADIUS client. The RADIUS client should respond with a
Disconnect-ACK or Disconnect-NAK message, which the gateway should
translate into an Abort-Session-Answer (ASA) message.
If the gateway receives a RADIUS Disconnect-NAK response containing a
Service-Type Attribute with value "Authorize Only" and an Error-Cause
Attribute with value "Request Initiated", the Disconnect-NAK response
is translated into a Diameter Abort-Session-Answer (ASA) with a
Result-Code AVP of "DIAMETER_LIMITED_SUCCESS" sent to the AAA server.
Subsequently, the gateway should receive a RADIUS Access-Request from
the NAS, with a Service-Type of "Authorize Only". This is translated
into a Diameter AA-Request with an Auth-Request-Type AVP of
AUTHORIZE_ONLY and sent to the AAA server. The AAA server will then
reply with a Diameter AA-Answer, which is translated into a RADIUS
Access-Accept or Access-Reject, depending on the value of the
Result-Code AVP.
9.3. AVPs Used Only for Compatibility
The AVPs defined in this section SHOULD only be used for backwards
compatibility when a Diameter/RADIUS translation function is invoked
and are not typically originated by Diameter systems during normal
operations.
+---------------------+
| AVP Flag rules |
|----+-----+----+-----|----+
AVP Section | | |SHLD| MUST| |
Attribute Name Code Defined Value Type |MUST| MAY | NOT| NOT|Encr|
-----------------------------------------|----+-----+----+-----|----|
NAS-Identifier 32 9.3.1 UTF8String | M | P | | V | Y |
NAS-IP-Address 4 9.3.2 OctetString| M | P | | V | Y |
NAS-IPv6-Address 95 9.3.3 OctetString| M | P | | V | Y |
State 24 9.3.4 OctetString| M | P | | V | Y |
Termination- 295 9.3.5 Enumerated | M | P | | V | Y |
Cause | | | | | |
Origin-AAA- 408 9.3.6 Enumerated | M | P | | V | Y |
Protocol | | | | | |
-----------------------------------------|----+-----+----+-----|----|
9.3.1. NAS-Identifier AVP
The NAS-Identifier AVP (AVP Code 32) [RADIUS] is of type UTF8String
and contains the identity of the NAS providing service to the user.
This AVP SHOULD only be added by a RADIUS/Diameter Translation Agent.
When this AVP is present, the Origin-Host AVP identifies the NAS
providing service to the user.
In RADIUS it would be possible for a rogue NAS to forge the NAS-
Identifier attribute. Diameter/RADIUS translation agents SHOULD
attempt to check a received NAS-Identifier attribute against the
source address of the RADIUS packet, by doing an A/AAAA RR query. If
the NAS-Identifier attribute contains an FQDN, then such a query
would resolve to an IP address matching the source address. However,
the NAS-Identifier attribute is not required to contain an FQDN, so
such a query could fail. If it fails, an error should be logged, but
no action should be taken, other than a reverse lookup on the source
address and insert the resulting FQDN into the Route-Record AVP.
Diameter agents and servers SHOULD check whether a NAS-Identifier AVP
corresponds to an entry in the Route-Record AVP. If no match is
found, then an error is logged, but no other action is taken.
9.3.2. NAS-IP-Address AVP
The NAS-IP-Address AVP (AVP Code 4) [RADIUS] is of type OctetString
and contains the IP Address of the NAS providing service to the user.
This AVP SHOULD only be added by a RADIUS/Diameter Translation Agent.
When this AVP is present, the Origin-Host AVP identifies the NAS
providing service to the user.
In RADIUS it would be possible for a rogue NAS to forge the NAS-IP-
Address attribute value. Diameter/RADIUS translation agents MUST
check a received NAS-IP-Address or NAS-IPv6-Address attribute against
the source address of the RADIUS packet. If they do not match and
the Diameter/RADIUS translation agent does not know whether the
packet was sent by a RADIUS proxy or NAS (e.g., no Proxy-State
attribute), then by default it is assumed that the source address
corresponds to a RADIUS proxy, and that the NAS Address is behind
that proxy, potentially with some additional RADIUS proxies in
between. The Diameter/RADIUS translation agent MUST insert entries
in the Route-Record AVP corresponding to the apparent route. This
implies doing a reverse lookup on the source address and NAS-IP-
Address or NAS-IPv6-Address attributes to determine the corresponding
FQDNs.
If the source address and the NAS-IP-Address or NAS-IPv6-Address do
not match, and the Diameter/RADIUS translation agent knows that it is
talking directly to the NAS (e.g., there are no RADIUS proxies
between it and the NAS), then the error should be logged, and the
packet MUST be discarded.
Diameter agents and servers MUST check whether the NAS-IP-Address AVP
corresponds to an entry in the Route-Record AVP. This is done by
doing a reverse lookup (PTR RR) for the NAS-IP-Address to retrieve
the corresponding FQDN, and by checking for a match with the Route Record AVP. If no match is found, then an error is logged, but no
other action is taken.
9.3.3. NAS-IPv6-Address AVP
The NAS-IPv6-Address AVP (AVP Code 95) [RADIUSIPv6] is of type
OctetString and contains the IPv6 Address of the NAS providing
service to the user. This AVP SHOULD only be added by a
RADIUS/Diameter Translation Agent. When this AVP is present, the
Origin-Host AVP identifies the NAS providing service to the user.
In RADIUS it would be possible for a rogue NAS to forge the NAS-
IPv6-Address attribute. Diameter/RADIUS translation agents MUST
check a received NAS-IPv6-Address attribute against the source
address of the RADIUS packet. If they do not match and the
Diameter/RADIUS translation agent does not know whether the packet
was sent by a RADIUS proxy or NAS (e.g., no Proxy-State attribute),
then by default it is assumed that the source address corresponds to
a RADIUS proxy, and that the NAS-IPv6-Address is behind that proxy,
potentially with some additional RADIUS proxies in between. The
Diameter/RADIUS translation agent MUST insert entries in the Route-
Record AVP corresponding to the apparent route. This implies doing a
reverse lookup on the source address and NAS-IPv6-Address attributes
to determine the corresponding FQDNs.
If the source address and the NAS-IPv6-Address do not match, and the
Diameter/RADIUS translation agent knows that it is talking directly
to the NAS (e.g., there are no RADIUS proxies between it and the
NAS), then the error should be logged, and the packet MUST be
discarded.
Diameter agents and servers MUST check whether the NAS-IPv6-Address
AVP corresponds to an entry in the Route-Record AVP. This is done by
doing a reverse lookup (PTR RR) for the NAS-IPv6-Address to retrieve
the corresponding FQDN, and by checking for a match with the Record-
Route AVP. If no match is found, then an error is logged, but no
other action is taken.
9.3.4. State AVP
The State AVP (AVP Code 24) [RADIUS] is of type OctetString and has
two uses in the Diameter NAS application.
The State AVP MAY be sent by a Diameter Server to a NAS in an AA-
Response command that contains a Result-Code of
DIAMETER_MULTI_ROUND_AUTH. If so, the NAS MUST return it unmodified
in the subsequent AA-Request command.
The State AVP MAY also be sent by a Diameter Server to a NAS in an
AA-Response command that also includes a Termination-Action AVP with
the value of AA-REQUEST. If the NAS performs the Termination-Action
by sending a new AA-Request command upon termination of the current
service, it MUST return the State AVP unmodified in the new request
command.
In either usage, the NAS MUST NOT interpret the AVP locally. Usage
of the State AVP is implementation dependent.
9.3.5. Termination-Cause AVP Code Values
This section defines a mapping between Termination-Cause AVP code
values and RADIUS Acct-Terminate-Cause attribute code values from RFC
2866 [RADIUSAcct] and [RADIUSTypes], thereby allowing a
RADIUS/Diameter Translation Agent to convert between the attribute
and AVP values. This section thus extends the definitions in the
"Termination-Cause AVP" section of the Base Diameter specification.
The table in this section defines the mapping between Termination-
Cause AVP and RADIUS Acct-Terminate-Cause causes.
+-----------------------+
| Value |
+-----------+-----------+
Cause Value Name | RADIUS | Diameter |
------------------------------|-----------+-----------+
User Request | 1 | 11 |
Lost Carrier | 2 | 12 |
Lost Service | 3 | 13 |
Idle Timeout | 4 | 14 |
Session Timeout | 5 | 15 |
Admin Reset | 6 | 16 |
Admin Reboot | 7 | 17 |
Port Error | 8 | 18 |
NAS Error | 9 | 19 |
NAS Request | 10 | 20 |
NAS Reboot | 11 | 21 |
Port Unneeded | 12 | 22 |
Port Preempted | 13 | 23 |
Port Suspended | 14 | 24 |
Service Unavailable | 15 | 25 |
Callback | 16 | 26 |
User Error | 17 | 27 |
Host Request | 18 | 28 |
Supplicant Restart | 19 | 29 | [RAD802.1X]
Reauthentication Failure | 20 | 30 | [RAD802.1X]
Port Reinit | 21 | 31 | [RAD802.1X]
Port Disabled | 22 | 32 | [RAD802.1X]
------------------------------|-----------+-----------+
From RFC 2866, the termination causes are as follows:
User Request User requested termination of service, for
example with LCP Terminate or by logging out.
Lost Carrier DCD was dropped on the port.
Lost Service Service can no longer be provided; for
example, user's connection to a host was
interrupted.
Idle Timeout Idle timer expired.
Session Timeout Maximum session length timer expired.
Admin Reset Administrator reset the port or session.
Admin Reboot Administrator is ending service on the NAS,
for example, prior to rebooting the NAS.
Port Error NAS detected an error on the port that
required ending the session.
NAS Error NAS detected an error (other than on the
port) that required ending the session.
NAS Request NAS ended the session for a non-error reason not
otherwise listed here.
NAS Reboot NAS ended the session to reboot
non-administratively ("crash").
Port Unneeded NAS ended the session because resource usage
fell below a low-water mark (for example, if
a bandwidth-on-demand algorithm decided that
the port was no longer needed).
Port Preempted NAS ended the session to allocate the
port to a higher priority use.
Port Suspended NAS ended the session to suspend a virtual
session.
Service Unavailable NAS was unable to provide requested service.
Callback NAS is terminating the current session
to perform callback for a new session.
User Error Input from user is in error, causing
session termination.
Host Request Login Host terminated session normally.
9.3.6. Origin-AAA-Protocol
The Origin-AAA-Protocol AVP (AVP Code 408) is of the type Enumerated
and should be inserted in a Diameter message translated by a gateway
system from another AAA protocol, such as RADIUS. It identifies the
source protocol of the message to the Diameter system receiving the
message.
The supported values are:
1 RADIUS
9.4. Prohibited RADIUS Attributes
The following RADIUS attributes MUST NOT appear in a Diameter
message. Instead, they are translated to other Diameter AVPs or
handled in some special manner. The rules for the treatment of the
attributes are discussed in sections 9.1, 9.2, and 9.6.
Attribute Description Defined Nearest Diameter AVP
-----------------------------------------------------------------
3 CHAP-Password RFC 2865 CHAP-Auth Group
26 Vendor-Specific RFC 2865 Vendor Specific AVP
29 Termination-Action RFC 2865 Authorization-Lifetime
40 Acct-Status-Type RFC 2866 Accounting-Record-Type
42 Acct-Input-Octets RFC 2866 Accounting-Input-Octets
43 Acct-Output-Octets RFC 2866 Accounting-Output-Octets
47 Acct-Input-Packets RFC 2866 Accounting-Input-Packets
48 Acct-Output-Packets RFC 2866 Accounting-Output-Packets
49 Acct-Terminate-Cause RFC 2866 Termination-Cause
52 Acct-Input-Gigawords RFC 2869 Accounting-Input-Octets
53 Acct-Output-Gigawords RFC 2869 Accounting-Output-Octets
80 Message-Authenticator RFC 2869 none - check and discard
9.5. Translatable Diameter AVPs
In general, Diameter AVPs that are not RADIUS compatible have code
values greater than 255. The table in the section above shows the
AVPs that can be converted into RADIUS attributes.
Another problem may occur with Diameter AVP values that may be more
than 253 octets in length. Some RADIUS attributes (including but not
limited to (8)Reply-Message, (79)EAP-Message, and (77)Connect-Info)
allow concatenation of multiple instances to overcome this
limitation. If this is not possible, a Result-Code of
DIAMETER_INVALID_AVP_LENGTH should be returned.
9.6. RADIUS Vendor Specific Attributes
RADIUS supports the inclusion of Vendor Specific Attributes (VSAs)
through the use of attribute 26. The recommended format [RADIUS] of
the attribute data field includes a 4 octet vendor code followed by a
one octet vendor type field and a one octet length field. The last
two fields MAY be repeated.
A system communicating between Diameter and RADIUS MAY have specific
knowledge of vendor formats, and MAY be able to translate between the
two formats. However, given the deployment of many RADIUS vendor
formats that do not follow the example format in RFC 2865 [RADIUS],
(e.g., those that use a longer vendor type code) the translations in
the next two sections will not work in general for those VSAs. RFC
2865 states that a robust implementation SHOULD support the field as
undistinguished octets.
Systems that don't have vendor format knowledge MAY discard such
attributes without knowing a suitable translation. An alternative
format is under consideration [VSA], which proposes encodings that
would preserve the native information and not require vendor
knowledge in the gateway system.
The following sections are an example for translating RADIUS VSAs
that use the example RADIUS format, and Diameter VSAs that have type
codes less than 255, and value field lengths less than 252.
9.6.1. Forwarding a Diameter Vendor Specific AVP as a RADIUS VSA
For Type codes less than 255, the value field length MUST be less
than 252 or the AVP will be discarded. The RADIUS VSA attribute
should consist of the following fields;
RADIUS Type = 26, Vendor Specific Attribute
RADIUS Length = total length of attribute (header + data)
RADIUS Vendor code = Diameter Vendor code
RADIUS Vendor type code = low order byte of Diameter AVP code
RADIUS Vendor data length = length of Diameter data
If the Diameter AVP code is greater than 255, then the RADIUS
speaking code may use a Vendor specific field coding, if it knows one
for that vendor. Otherwise, the AVP will be ignored. If it is
flagged as Mandatory, a "DIAMETER_AVP_UNSUPPORTED" Result-Code will
be returned, and the RADIUS message will not be sent.
9.6.2. Forwarding a RADIUS VSA as a Diameter Vendor Specific AVP
The Diameter AVP will consist of the following fields:
Diameter Flags: V=1, M=0, P=0
Diameter Vendor code = RADIUS VSA Vendor code
Diameter AVP code = RADIUS VSA Vendor type code
Diameter AVP length = length of AVP (header + data)
Diameter Data = RADIUS VSA vendor data
Note that the VSAs are considered optional by RADIUS rules, and this
specification does not set the Mandatory flag. If an implementor
desires a VSA be made mandatory because it represents a required
service policy, the RADIUS gateway should have a process to set the
bit on the Diameter side.
If the RADIUS receiving code knows of vendor specific field
interpretations for the specific vendor, it may employ them to parse
an extended AVP code or data length. Otherwise the recommended
standard fields will be used.
Nested Multiple vendor data fields MUST be expanded into multiple
Diameter AVPs.
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