H323 and GK basic configurations

Posted: 9th March 2011 by An in Cisco GW/GK

Today I am going to implement a H323 gateway and Gatekeepers in my lab. This is going to be in my lab, so I am going through with the basic configurations which is require in CCIE Lab.. Grin  So pretty basic

One more important thinks…. I saw a lot of videos, read a lot of PDFs and I found out below confign to configure the scenario. But watching and reading is simple, until and unless we do it in real….Chic

Yes, I got an error while configure my router.

In config mode I am unable to give “gatekeeper” command… .YQuestion

And I found it’s coz of IOS version…  I was using version which described in CCIE blue print, then what?

While you downloading the IOS software, give importance to the descriptions and read it carefully…

For example, when downloading Cisco 2811 IOS may we have the following options:

  • CISCO IOS IP Voice
  • CISCO IOS Enterprise Base
  • CISCO IOS Advanced Security
  • CISCO IOS SP Services
  • CISCO Advanced IP Services
  • CISCO IOS Enterprise Services
  • CISCO IOS Advanced Enterprise Services
  • Cisco Int Voice/Video: GK, IPIP GW, TDMIP GW

Where first time I selected “CISCO IOS IP Voice” but with this I am not able to configure GK…

So I download “Cisco Int Voice/Video: GK, IPIP GW, TDMIP GW” This time it’s done perfectly… Cool

H323 is a stack of many protocols, H.225 is using for call signaling H.245 for media negotiation like codec selections

GK is a centralized point which is act like a bridge or communicator between different gateways and acts as registration ends point where GW registered with it. BY selecting gateway it will route calls to a particular.

In H.323 and Gatekeeper scenario, message exchange will happen in three points.

Gatekeeper: – GRQ (Gatekeeper request) GCF (Gatekeeper confirmation) GRJ (Gatekeeper reject)

Gateway: – RRQ (Registration request) RCF (Registration confirmation) RRJ ((Registration reject)

Endpoints: – ARQ (Admission request) ACF ((Admission confirmation) ARJ (Admission reject)

Two things are important while configure a GK

Tech-prefix– gk use this make a call routing decisions (1#)

Zone – group of device under a GK (Zone name – zone_01)

Local numbers I used in this senario; 1* number plan registered with CUCM and 44* number plan registered with CME in BR2

This scenario will split in to Four:-

  • Step1: configuring a gatekeeper
  • Step2: Configure & register H.232 gateway with GK
  • Step3: Create GK and trunk in CUCM
  • Step4: configure GK for call routing

Step1: configuring a gatekeeper:-

(config)#Gatekeeper – enable the router as GK

(config-gk)#Zone local zone_01 cisco.com– gives a name to zone, give domain name (should give something) and bind the loopback0 ip with GK

(config-gk)#no shut– coz by default GK status is shut down

Step2: Configure & register H.232 gateway with GK:-

(config)#interface loopback 0– enter in to loopback interface

(config-if)#h323-gateway voip interface – define as h323 gateway

(config-if)# h323-gateway voip bind srcaddr – bind the loopb0 add as source add

(config-if)# h323-gateway voip h323-id Br2_uk– give a name to gw, this will register with GK

(config-if)# h323-gateway voip id zone_01 ipaddr – give the GK id and IP add

(config-if)# h323-gateway voip tech-prefix 1# – define the tech prefix for call routing

(config-if)#gateway – to enable gateway globally

Step3: Create GK and trunk in CUCM:-

  • Device > Gatekeeper > – save


  • Device > Trunk > H.225 trunk (Gatekeeper controlled) > next >
  • Device name <any name(trunk_gk_hq_1)>
  • Inbound calls > significant digits* <extension(4)>
  • Gatekeeper name >
  • Terminal type > gateway
  • Technology prefix > 1#
  • Zone > zone_01
  • Save

Step4: configure GK for call routing:-

(config)#Gatekeeper– login in to GK mode

(config-gk)#zone prefix zone_01 44* gw-priority 0 trunk_gk_hq_1– very less priority set for 44 dialing number, so that calls will not use the cucm trunk.

(config-gk)#zone prefix zone_01 44* gw-priority 10 Br2_gw– set the 44 calls routed to BR2 router and Br2_gw is the name of branch 2 h323 gateway.

(config-gk)#zone prefix zone_01 1* gw-priority 0 Br2_gw – starting with 1 call very less priority to BR2

(config-gk)#zone prefix zone_01 1* gw-priority 10 trunk_gk_hq_1 – guessed right calls will routed to CUCM

(config-gk)#arq reject-unknown-prefix – call routing will only happen to the prefix what we configured above

 SHOW commands:-

Sh gateway – status of gateway

Sh gatekeeper endpoints – registered devices with GK

  1. cisco 3845 says:

    The essay is very wonderful Thanks for the sharing Hope the author can update it ofte

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