Subject: [Dime] FW: handling of unexpected direction of the messages

From: D'Alessandro Rosalia <[email-masked]>
Date: Sat, 21 May 2016 13:29:07 +0000

Dear All,
TIM would like to submit a question on how to handle the conditions when a Diameter node receives an unexpected message from another Diameter peer entity.
The specific scenario we are addressing is when a node named A gets a Diameter message which is correct from the protocol viewpoint but shall not be sent to this node A because this node A is not expected to receive the message but to send it from the application viewpoint. As an example this happens when the receiving node A is the legitimate sender of the message. Consequently this node A should expect an answer for this message and not a request.

In our opinion, if an entity receives a request that it should not receive because, in the protocol, it should send the request and wait for the answer, this is clearly an error case. The request should not be processed and the result-code to use could be "DIAMETER_COMMAND_UNSUPPORTED"  (command code not supported by the receiver) or alternatively, DIAMETER_UNABLE_TO_COMPLY.

It seems that in the current version of the RFC 6733 this condition is not clearly addressed and we would like to include this case.
What is your opinion?

Looking forward to your reply,

Rosalia d’Alessandro

------------------------------------------------------------------
Telecom Italia Information Technology
Rosalia d’Alessandro
Technical Security.SecurityLab
G.Reiss Romoli, 274, 10148 Torino
+39 011 228 8217
+39 3316001152