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Can we connect multiple HSS to MME without DRA?

+2 votes
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As per my understanding DRA is must to connect MME to multiple HSSs.

My question is: is there any considerations for connecting number of HSS's to MME without DRA, or its just a must to have DRA for connecting HSS's at VPLMN's?

posted Mar 9, 2015 by anonymous

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2 Answers

0 votes

There is no such binding of using DRA for the roaming cases for MME to HSS connection. You can always opt for DEA (Diameter Edge Agent) for such cases if you don't want to use DRA.

answer Mar 9, 2015 by Salil Agrawal
0 votes

On behalf of Bart -

It's not obligatory to use DRA in any case - single or multiple.

The other thing is you would like to use DRA for roamers. Keep in mind this is business and the VPLMNS are your competitors - you don't want to tell them much about your infrastructure. How many HSS you are using as it's very easy to estimate how many subscribers you serve or predict your call model based on the signaling to HSS nodes.
It's not a secret how many sessions max each box can handle, you can google that for HP.

Others advantage of using the DRA is.. Amount of changes you would have to do without it. How many roaming partners you have? How many GGSN PGW they have? Each is peer number is quite high. Plus the security, DRA would be just after the FW.

Hope this helps.

answer Mar 9, 2015 by Salil Agrawal
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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
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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.

+2 votes
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It would be great if you give your valuable suggestion ?

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