Subject: [Dime] failover scenario

From: "Poscic, Kristian (Kristian)" <[email-masked]>
Date: Tue, 11 Dec 2012 00:39:25 +0000

Does anyone know what would be the mechanism in Base Diameter to handle the following scenario properly:

-          There are two NASes that run certain application (Gx in this case)

-          They are in standby/active mode - in other words, the NAS1 is active and has peering session with DMR-SRV. NAS2 is synched to NAS  (Gx session are synched and diameter entities are synched too - origin-host, origin-realm, possibly more AVPs...). However NAS2 is standby and therefore quiet (no peering session is established with  DMR-SRV)

-          If the NAS 1 fails, the NAS2 takes over (it detects the failure and activates itself along with application that is running on top of Base Diameter)

-          At this point, NAS2 will establish a peering session with DMR-SRV. The only difference between NAS2 and the failed NAS1 is the Host-IP-address (as AVP and also the source IP address in the transport => src IPs are not synched).

-          When the NAS2 sends CER and the peering session is established with DMR-SRV, will the DMR-SRV automatically update its routing table and see that nas.example.com is now at IP2 and not at IP1. Consequently all subsequent messages would be exchanged between NAS2 and DMR-SRV

-          All this presuppose that there are no changes on the application layer (Gx for example is completely synched between NASes) and the re-routing is handled at the Base Diameter.

-          Would this work and if not what would be the recommended approach that is compliant with Base Diameter so that the routing in DMR-SRV is updated properly?

Origin-host =                      nas.example.com
Origin-realm=                    example.com
Host-IP-Address =           IP1

---------
|NAS1 | -------------------
---------                                 |
                                                |                              --------------
                                                |-----------------| DMR-SRV|
---------                                 |                              --------------
|NAS2 |-------------------
---------

Origin-host =                      nas.example.com
Origin-realm=                    example.com
Host-IP-Address =           IP2

Thanks,
Kris