Categories: CCIE , Cisco , Cisco VOIP -  Comments
For the past several days, I have immersed myself in everything Gatekeeper. As I had stated early on, IPIPGW and Gatekeepers have been a weak area for me due to the fact that I have never come across a need to deploy one for a customer. When studying for my CCVP and my CCIE voice written exam, I had studied the theory and “lab’d” up some basic configurations, but Gatekeepers have always been an intimidating beast to me, until now!
Friday, I spent the evening watching IPexpert’s VLecture on H.323 Gatekeepers Basics by Mark Snow. This was a very good review of Gatekeeper theory and basic configuration and got me in the mindset for the weekend. I spent most of the day Saturday in the lab working through IPexpert WB vol 1 Lab 5: Gatekeepers. I was able to work through this lab a couple of times completing such tasks as routing calls from CCM to CME via an IPIPGW, routing intl calls to a remote gatekeeper and into CME via the PSTN, configuring gatekeeper CAC and security, registering CCM to a gatekeeper using a default tech prefix, and registering CCM E164 numbers statically to a gatekeeper, to name a few. In addition, I became very familiar with two hidden debug commands, debug gatekeeper main 10 and debug gatekeeper call 10.
One task that I initially had issues with configuring was to enable my gatekeeper to route calls through my IPIPGW located on the same router. I was asked to allow an ATA to register to the gatekeeper with a DN in a new local zone. Calls coming from CCM should be in G.711 and flow to the ATA using G.729. After configuring this, I was able to make a call from an IP phone at HQ to a phone attached to the ATA, but after about 4 seconds, it would go to fast busy. My first thought was that my transcoder was not being invoked for the g711 to g729 conversion. After verifying that my transcoder configuration was correct and looking over the rest of my configuration several times, I FINALLY came across what my issue was. In CCM, on my Gatekeeper-controlled trunk, I noticed that I had the checkbox for Wait for Far End H.245 Terminal Capability Set checked. Once this setting was unchecked, I was able to make calls to and from an HQ IP phone and ATA successfully. After a little research, I found that the issue is with the version of IOS I am using (same as seen on the lab exam) which does not support the Empty Capabilities Set method for Supplementary services used by CallManager.
My plan is to continue with Gatekeepers the rest of this week working through the specific Gatekeeper tasks in all of my workbooks as well as finish reading the Gatekeeper configuration guide. This weekend, and into next week, will be spent on Dial Plan, Media and High Availability.