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DIAMETER: Why DPR and DPA messages don't contain Destination-Host and Destination-Realm AVPs ?

+1 vote
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Can someone please explain why few "request" message contains Destination-Host and Destination-Realm AVPs and few of them not ?

posted Mar 15, 2016 by Harshita

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1 Answer

+1 vote

Hi Harshita,

If we see CER/CEA message these messages also doesn't contain Destination - Host and Destination -Realm AVP.

The reason for Capabilities exchange as we know it is based on discovery of a peer's identity and its capabilities (protocol version number,the identifiers of supported Diameter applications, security mechanisms, etc.

Since Opposite to CER/CEA is DPR/DPA.

Also section 6.1 of RFC - 6733 clearly states that "A request that is not able to be proxied (such as a CER) MUST NOT contain either Destination-Realm or Destination-Host AVPs."

I guess that is the reason for which CER/CEA/DPR/DPA doesn't contain Destination-Host and Destination-Realm.

Please correct if my above explanation is wrong.

Thanks

answer Mar 17, 2016 by Chinmoy Padhi
Similar Questions
+3 votes

I am trying to clarify the allowed naming convention for the host and realm of a diameter node. This relates to the values used in the Origin-Host AVP (AVP Code 264) and Origin-Realm AVP (AVP Code 296). I have reviewed the Diameter RFCs and cannot find a definitive answer to this issue.

The reason for asking this question is that I am in discussion with a vendor of a Diameter Routing Agent (DRA) which claims that the host of a diameter node has to be in the format host.realm.
(1) Example of the only allowed format according to the vendor:Origin-Realm: example.com
Origin-Host: node.example.com
I want to clarify if multiple subdomains are allowed to be added in the host without being present in the realm.(2) Example:Origin-Realm: example.com
Origin-Host: node.site1.example.com

According to the vendor, the example 2 is not allowed. To have the host as in example 2, the realm will have to be site1.example.com.
Could someone please clarify this naming issue or point me to the standard where this is defined.

+2 votes

3GPP TS 29.272 says in section 7.1.6/ Routing considerations the following sentence:
If an MME or SGSN knows the address/name of the HSS for a certain user, and the associated home network domain name, both the Destination-Realm and Destination-Host AVPs shall be present in the request......

In Diameter Base Protocol RFC 6733 you can read the following :
6.1.4. Processing Local Requests
A request is known to be for local consumption when one of the following conditions occurs:
o The Destination-Host AVP contains the local host’s identity;
o The Destination-Host AVP is not present, the Destination-Realm AVP contains a realm the server is configured to process locally, and the Diameter application is locally supported; or
o Both the Destination-Host and the Destination-Realm are not present.

Following erroneous Scenario:
1) The MME sends a Request to the Destination Host e.g. HSS_ABC01.xxx via the DRA. The Request contains Destination-Host and Destination-Realm…
2) But what happens when this HSS_ABC01.xxx is unavailable (out of order)? Would the DRA send/forward the Request from MME to a second HSS (front end)?, e.g. hssDEF01.xxx?
3) Would the 2nd HSS Frontend “hssDEF01.xxx” complain that the Destination Host does not match as DRA sent to 2nd HSS frontend the Request with Destination-Host = HSS_ABC01.xxx
-->should the DRA be smarter when the 1st HSS Frontend is unavailable ? my question is what can DRA do in such case when the original destination is out of order?

FYI:
DIAMETER_UNABLE_TO_DELIVER 3002
This error is given when Diameter cannot deliver the message to the destination, either because no host within the realm supporting the required application was available to process the request or because the Destination-Host AVP was given without the associated Destination-Realm AVP.

+3 votes

What would be the standard value for the Origin Host and realm from the MME and HSS?

My question is regarding the for roaming in the GSMA is always mention that all the configuration should contain the epc.mncXXX.mccXXX.3gppnetwork.org.

But we are a little confuse with the realm configuration from both sides. If there any standard value we need to configure to comply with other carriers when we approach roaming services ?

0 votes

In case there is a DRA between PGW and PCRF, then what should ideally be sent in the Destination-Host AVP in the CCR-Initial messsage?Do we send the Destination-Host name for the final destination of the PCRF or is it the next hop peer ; which is the DRA in this case?

+6 votes

Can someone please explain difference between these two. Could both Result-Code and Experimental-Result AVPs be used in same diameter or only one of them is allowed ?

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