Subject: [AAA-WG]: Diameter Client request routing

From: Joe Harvell <[email-masked]>
Date: Wed, 14 Jan 2004 11:59:42 -0600

I have reviewed 2.6 (Peer Table), 2.7 (Realm-Based Routing Table), 5.1 (Peer Connections), and 5.2 (Diameter Peer Discovery) of Diameter Base Protocol, and I am a little confused about how a Diameter Peer is to be selected for sending a request from a Diameter Client.

Consider the case of a Diameter Client that does not implement Diameter Peer Discovery.  This means that Diameter Peers are statically configured.  The Capabilities Exchange process will definitely identify the Realm and Host of each Diameter Peer.  However, the only cases in which a peer can be identified as a candidate next hop for sending a particular request are as follows:

	1) when its Realm matches the Destination-Realm of a message with Destination-Realm only; and
	2) when its Realm and Host match the Destination-Realm and Destination-Host of a message with a Destination-Realm and Destination-Host.

So how does a Diameter Client identify a candidate peer for sending messages in the other cases?

Section 5.1 indicates that a Diameter Node should have established connections with a minimum of two (a primary and possibly multiple secondary) peers per realm.  Does the "realm" in this context mean that both peers are members of the same realm, or that both peers can route messages to a given Destination-Realm?  Can Diameter Agents forward requests for a Destination-Realm that is not their Realm?

When a Diameter Client has a request with a Destination-Realm and Destination-Host, will all the primary and secondary peers described in 5.1 be able to route the request to that Destination-Host in that Destination-Realm?

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Joe Harvell
Shasta GGSN Development
Nortel Networks
+1 972.685.4886