Example with static realm routes

In this example, Gx and Gy traffic, destined for the remote realms Realm-3 and Realm-4, is balanced over two DRAs. Gx traffic destined for Realm-4 flows through Node-B, while Gy traffic destined for Realm-3 flows through Node-C, according to the preference of the static routes. If the connection to one of the peers fails, the surviving connection takes over as shown in Figure: Reaching remote realms.

Figure: Reaching remote realms

NASREQ traffic, which is destined for the directly-connected Realm-2 flows through Node-B because it has a lower peer index, while the peer preference is the same as on peer Node-C as described in Table: Peer table and Table: Realm routing table . Only when the communication to this peer fails does Node-C be selected as the new peer.

>config>aaa# info 
----------------------------------------------
        diameter
            node "sr" origin-realm "realm-1" create
                peer index 1 "node-b" create    
                    address 192.0.2.2                    
                    preference 5
                    route index 1 realm realm-3 application gx 
                          preference 10 
                   route index 2 realm realm-4 application gy 
                          preference 20
                   no shutdown
                exit
                peer index 2 "node-c" create
                    address 192.0.2.3
                    preference 5
                    route index 1 realm realm-3 application gx 
                          preference 20 
                    route index 2 realm realm-4 application gy 
                          preference 10
                    no shutdown
                exit
            exit
       exit

Table: Peer table
Host identity	IP address
Node-B	192.0.2.2
Node-C	192.0.2.3

Table: Realm routing table
Realm name	App ID	Peer	Entry	Preference
Realm-2	0xffffffff	Node-B	dynamic (learned)	5
Realm-2	0xffffffff	Node-C	dynamic (learned)	5
Realm-3	Gx	Node-B	static	10
Realm-3	Gx	Node-C	static	20
Realm-4	Gy	Node-C	static	20
Realm-4	Gy	Node-B	static	10

The NASREQ routing in this case can be configured in several ways:

with the same preference for both peers (as in the example above), where the peer with the lowest index prevails

with different peer preferences as shown in the example below

*A:right-b4>config>aaa# info 
----------------------------------------------
        diameter
            node "sr" origin-realm "realm-1" create
                peer index 1 "node-b" create    
                    address 192.0.2.2                    
                    preference 10
                    no shutdown
                exit
                peer index 2 "node-c" create
                    address 192.0.2.3
                    preference 5
                    no shutdown
                exit
            exit
        exit

In this case, the preferred NASREQ path is through Node-C.

with static routing

*A:right-b4>config>aaa# info 
----------------------------------------------
        diameter
            node "sr" origin-realm "realm-1" create
                peer index 1 "node-b" create    
                    address 192.0.2.2                    
                    preference 10
                    no shutdown
                exit
                peer index 2 "node-c" create
                    address 192.0.2.3
                    preference 10
                    route index <index> realm realm-2 application nasreq
                        preference 5 
                    no shutdown
                exit
            exit
        exit

In this case, the NASREQ path is through Node-C because the preference of the static route is the lowest.