Posted on January 26, 2011 by Janine Lim
This post continues our 20 Day Challenge to understand the technical aspects of videoconferencing.
No Internet, No Videoconference. A phrase we often say to the teachers and educators we support. So in today’s post, let’s look at some basic things to check when you can’t connect anywhere.
1. Is the Internet working in the school/district?
Power outages, cut cables, big storms. You never know what will take out your Internet connection. If you don’t have Internet anywhere in the school, your videoconference isn’t going to work either!
2. Is the Ethernet cable connected and in good condition?
- Follow the Ethernet (Internet) cable from the videoconference system to the wall Ethernet jack. Is it plugged in? Is it mangled looking? If the cart rolls over the cable too many times, the cable might not be functioning properly.
3. Is there activity on the link or status lights?
- Check the link and status lights next to the spot where the Ethernet cable plugs in on the videoconference system. Are they on? Are the blinking? If not, you’re not plugged into a live jack.
- It’s a good idea to label the correct jack in the wall. Double check with your district technical support personnel to make sure that it is the correct one.
4. Can you call outside your school/district/network?
- Have a list of test sites handy.
- Call to one or more test sites and see if you get audio and video.
- Make sure both sites trying to connect are able to connect to a test site.
5. Did you give the correct IP address?
- Note to network/VC people: set up the endpoint so that it shows it’s public IP on the front page. It’s not the end user’s fault if they take the IP off the screen to give out their number and it’s a 10. internal address!
- Make sure you know your own IP address. It is usually listed on the front screen of your videoconference system.
Finally, double check your NAT or firewall settings to make sure they are configured correctly.
- What tips do you have to share for troubleshooting your videoconference?
- Any other common problems you’ve run into? Please share!
Team-written by Janine Lim, Shane Howard, and Roxanne Glaser. The opinions expressed in these posts are based on our collective video conference experience connecting classes across multiple networks to connect them to zoos, museums, experts and other classes during the past 10 years. This series of posts reflects our usage and understanding, not that of any vendor or manufacturer. No one is paying us to write these. We are just sharing what we have learned.
Filed under: Techie Stuff | Tagged: H.323, network, video conference, videoconferencing | Comments Off
Posted on July 13, 2009 by Janine Lim
After the discussions that arose from my posts last week about mentoring, I thought it might be helpful to share some of the ways that I work with the tech coordinators in our districts.
A Little History
First, a little history. I’m at heart and by training a teacher, and the technology scared me at first. When we started with VC in 1999, my supervisor did all the technical stuff. I didn’t want to touch it. But over time I learned more about it, and sometimes say that I’ve learned more about networks than I ever wanted to know! Experience was my teacher. So I encourage you to try to learn what you can about how VC works on your network!
Word Wall in the Jazz Workshop
I really started to learn more when we made the switch to IP videoconferencing in 2005. An early workshop that I attended in 2006 was “Understanding and Troubleshooting Videoconferencing Networks.” I thought for sure I wouldn’t get anything out of it and that it would be over my head. But surprisingly, I’d experienced enough situations in our IP calls that I learned something and actually understood it! Some basic concepts (written in my lay language!) include:
- IP numbers that start with 10. are internal addresses and people outside can’t call them.
- Most videoconferences are at 384K. Compare that to the amount of available bandwidth on a typical day to know if you’ll be able to sustain a “good enough” videoconference.
- Packets are little pieces of info sent over the network. In email the packets eventually get there, get together, and give you an email. But in VC, if the packets don’t show up in time, they get thrown away. Hence, packet loss. Usually 2% packet loss or higher becomes intolerable.
- A NAT is network address translation, and both the codec/endpoint and the firewall/router need matching settings for NAT to work. This is because the endpoint/codec needs that info to set up the packets properly.
- An IP videoconference call is set up on port 1720. After that the two codecs negotiate which ports to use for the audio and video streaming. This is what’s going on when it rings & rings.
- If you’re using a gatekeeper, ports 1718 and 1719 are used to find and register with the gatekeeper. More on ports here.
- Two great resources to learn more about H323 and your network are: H323 and Firewalls from MOREnet in MO; and UKERNA/Janet Security Guide for H323 from the UK.
Working with District Tech Coordinators
- It’s important that they understand the impact of VC on their network. See the notes above. Even if you don’t understand how it all works, it helps to know a bit of “techie language”, enough to explain what VC does. I’ve found VTC Talk a useful site to learn to talk to the technicians. It’s desirable to be able to point them in the right direction of what to do to make it work, and where to find answers.
- It’s also important that those of us in VC realize that network technicians have legitimate concerns about the health of their network. Listen. Realize also that they are busy and usually overworked. Hear their side. Send them to third party resources (such as those above) to explain the issues in their language.
- We try to do summer installations and upgrades if at all possible. During the school year, there are so many problems to fix, it’s hard to find time to learn new things or change network policies to make VC work. It can take 3-6 months to get VC working on your network during the school year. Better to do it in the summer.
- Know your audience. Some tech coordinators in our districts came from the education side, and others came from business/technology. Some of them are interested and want to know a lot about how to use VC in the curriculum. Others know that the teachers want and use it, and all they want to know is what needs to be done on the network. Tailor your message accordingly!
What do you think? Do you use any of these strategies? Do you have any other tips? Please comment!
Filed under: Techie Stuff | Tagged: firewalls, H323, network | 2 Comments »