Translation Profiles Examples: Inter-site Call Routing Failover

In the translation profile example, we will utilize a translation profile to manipulate digits for inter-site call routing when the voip dial peer is not available (WAN down) or when the H.323 gatekeeper sends the H.323 gateway an admission rejection (ARJ) indicating that there is no bandwidth available or the gatekeeper cannot resolve the phone number.

The H.323 gateway configuration required to register with the gatekeeper is as follows:

Interface loopback 0
Ip address 10.1.1.254 255.255.255.255
H323-gateway voip interface
H323-gateway voip bind srcaddr 10.1.1.254
H323-gateway voip h323-id NYC
H323-gateway voip id GlobalKnowledge 192.168.254.1

The h323-gateway voip interface command turns on H.323 gateway functionality on the logical loopback interface. I used a logical loopback interface in this example because loopback interfaces never go down. A loopback interfaces will allow the H.225 registration admission status (RAS) signaling to leverage any physical interface on the router providing resiliency against link failures. The bind command is critical in environments with CUCM because CUCM will only accept calls from an IP address configured as an H.323 gateway in CUCM. The router will choose a source IP address by doing a recursive lookup against the routing table to see which interface is closest to the destination.

The h323-id (case sensitive) command configures the identifier of the gateway that will be used in the gatekeeper registration. The voip id command points the gateway to the gatekeeper named GlobalKnowledge (case sensitive) at IP address 192.168.254.1. The “show gateway” command can be used on the H.323 gateway to verify the gatekeeper registration status. The “show gatekeeper” command can be used on the gatekeeper to verify the gateway registration status on the gatekeeper.

Now that we have the gateway configured to point to the gatekeeper, the configuration can be leveraged in one or more voip dial-peers. The session target ras command used in dial peer 200 points any 5 digit pattern beginning with a 1 to the gatekeeper.

Dial-peer voice 200 voip
Destination-pattern 1….
Preference 1
Session target ras

If the gatekeeper rejects the call because there is not enough bandwidth available, dial-peer 100 has been configured to match on the same destination-pattern providing dial-peer hunting capabilities (call coverage). Dial peer 100 is used as a secondary dial peer because it is configured with a lower priority preference (preference 2) than dial peer 200 (preference 1). Dial peer 100 is using a translation profile called pstn-outgoing to manipulate digits.

Dial-peer voice 100 pots
Destination-pattern 1….
Translation-profile outgoing pstn-outgoing
Preference 2
Port 0/0/0:23
The translation profile of pstn-outgoing is translating the 5 digit dialing into an 11 digit DNIS that is routed out the PRI interface (0/0/0:23).

voice translation-rule 1
rule 1 /^1…./ /1408551…./
!
voice translation-profile pstn-outgoing
translate called 1

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• gk gatekeeper arj arq h.323 ras h.323-id