Important Session AVPs and their usage in session.
1) Termination-Cause AVP
It shall tell the reason of STR Session-Termination-Request triggered by client.
2) Session-Binding AVP
Usage of this avp is application specific,This avp may be present in any of the application specific authorization messages to inform the client that all future re-auth messages MUST be sent to same authorization server that has trigger the answer message.This avp may tell that STR to be sent to same authorization server.Values of AVP
All future re-auth messages to be sent to same authorization server, and MUST not include Destination-Host AVP.[because node destination is fixed.]
STR message be sent to same authorization server,and MUST not include Destination-Host AVP.[because node destination is fixed.]
All future messages pertaining to accounting be sent to same accounting server.,and MUST not include Destination-Host AVP.[because not destination is fixed.]
This avp used to define behavior of node in case of failure. What a node should do if it is unable to deliever re-auth or STR message. This avp may be present in any of the application-specific messages that does not have session-Binding AVP or all bits of this avp are not set, because Session-Binding AVP forces client to send re-auth or STR to specific server. Session-Server-Failover Avp can have one of the following values.
If re-auth or STR message delivery fails, then terminate the service and don't make subsequent attempts. This is Default Value for AVP.
Resend the message without the Destination-Host AVP.
Unable to send Re-Auth, assumes that re-auth succeeded. If unable to send STR means, Terminate session.
if second attempt also fails then allow service.
4) Multi-Round-Time-Out AVP
This avp should be present in answer message whose Result-Code AVP is set to DIAMETER_MULTI_ROUND_AUTH, indicating the number of seconds the user shall respond to authentication request.
5) Class AVP
This avp used by server to return state information of access device. there can be multiple class avps in a message.