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Before I forget this, today I had an emergency call from one of my dearest customers and friends. This conference room had having choppy sound, but strange it was, that it only happened when the call came from the PSTN network (through an external profile), and all local registered endpoints were okay. His scenario was the following:
- Bare metal server with 8 Xeon
This email address is being protected from spambots. You need JavaScript enabled to view it. - 8 GB of RAM
- 16 GB of Swap, only 2kB used
- FreeSWITCH 1.6.8
- FusionPBX 4.1 (devel branch)
For those who don't know, conference rooms are very handy. They allow us to talk among many endpoints at the same time, it is like being in the same room.
So here is how I fixed it.
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In my opinion, PowerDNS gives more flexibility to a system administrator to deal with their DNS zones. Things such as having different backends, and mixing dynamic and static answers are hard to archive with bind. In this post, I will write about how to put a Bind-like zone into PowerDNS. This will open possibilities to have some very cool features such as High Availability and Load Balancing through DNS protocol.
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This weekend a friend of mine asked me to help deploy a high-availability environment with virtualization in the cloud. His scenario is to have two big servers hosted in different data centers and with virtualization to be able to have a high availability system. The challenge here is the server synchronization, and to be more accurate the routing.
As this must satisfy disponibility, the design of this deployment must have the less points of failures as possible. You may think that the tunnelling can be done with OpenVPN and you are right, it could. But having OpenVPN adds an extra daemon to take care of. Don't take it wrong, OpenVPN is the software I use to do VPN but in this case, I think there is something better. After thinking, I decided to use GRE tunnels. GRE tunnels have been in the Linux system for years, and although they are not very known you may be a user of it without knowing. PPTP, the VPN protocol uses GRE to transmit information.
The GRE approach will make this very easy. As in this deployment, there are no plans to add a third server, using GRE to set up a point-to-point interface is very easy and reliable and it will make all the internal networks within the servers routable to each other.
Read more: Using GRE tunneling to deploy a High Availability Environment in the Cloud
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FreeSWITCH it is an excellent soft switch, you can do all your imagination asks for. If you combine it with FusionPBX you can have a very nice experience managing your switch. However, the out-of-the-box configuration is not suitable for everyone. It happens I have a customer who uses the Freeswitch for call termination in a very particular way. They only serve a busy or calling tone (depending on some conditions) to all incoming calls.
The big issue here was the stress, the carrier they are using has a 3-second tolerance timeout and they need to serve as many calls as possible. The FusionPBX server was having an issue when receiving more than 200 cps, the carrier was reporting times out (more than 3 seconds to answer). In this article, I will try to put notes of what I did to increase the cps up to 450 (as 450 was the number my customer reported). Please note that VoIP switches are not intended for end-user use, some of the techniques won't apply to other kinds of deployments.
Read more: Making a FusionPBX with FreeSWITCH to hold a High CPS Index
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These days all is in the cloud. Being in the cloud means your service or information is on someone's server without knowing exactly where it is. Being in the cloud is as easy as renting some VPS'es. Now you are "in" with the technology, but that it is not enough. Depending on your business, you may be worried about being online as much as possible and at the same time keeping your costs down. If you do an Internet search, you will find that the most common high availability option is having all servers in the same data center by sharing an IP (also known as floating IP). This could work, but you will have all your eggs in the same nest (not very smart for high availability), there are some VPS companies with this option, but again, to allow the IP switch the containers must be in the same collision domain (that not always is the same sub-network) which it means again, all eggs in the same nest.
Well, today is your lucky day, there is another approach that allows high availability: smart DNS balancing. DNS will let the end-points get the correct IP depending on some network, software and business conditions. This means that you can have VPS'es spread around the world, and depending on the real-time decision they may get IP A or IP Z. If you do a little research, you will find some professional solutions such as F5 which it is crazy expensive and it is a headache to make it work properly. So, I have my solution: my very own smart DNS software.
I will introduce this software to you and I will show a brief setup.
Read more: Setting Up a Smart DNS for Low Lattency Connections
