Using ClusterLabs Pacemaker with OpenSIPS

Summary In this article we examine how Pacemaker and Corosync might be used to supercharge OpenSIPS and build a highly available clustered solution. The focus is entirely on High Availability rather than any form of load sharing. This means we are looking for a way to have more than one server contactable on the same IP … Read more

VoIP QoS in practice: About Network Congestion

My previous two articles explored QoS tagging of voice data packets using ToS/DiffServ values and of Ethernet frames using CoS or Priority values. QoS is often advocated as an essential part of any self-respecting VoIP solution and there is no doubt it can make a big difference in the right circumstances. However, it would be … Read more

VoIP QoS Settings – part 1

The QoS settings on VoIP phones and related equipment can be perplexing. Here, I will attempt to explain what parameters like CoS, ToS, DiffServ and DSCP really mean and offer practical suggestions for the values that should be assigned to them. Part 1 of this article starts with a broad overview and then focuses on … Read more

Clustering OpenSIPS for High Availability – Part 3

In this, part 3, we examine how a virtual IP address can be switched between two Linux servers to provide an active/standby failover and how this impacts on OpenSIPS. Part 2 investigated the implications for far-end NAT traversal of clustering two OpenSIPS servers and concluded that the best solution is the use of a virtual IP address. … Read more

Clustering OpenSIPS for High Availability – Part 2

In this, part 2, we investigate the implications of using more than one IP address on an OpenSIPS server and how this impacts on far-end NAT traversal. We will also see how the use of a virtual IP address can overcome these problems when clustering two OpenSIPS servers. Part 1 reviewed why we might want … Read more

Clustering OpenSIPS for High Availability – Part 1

Why cluster OpenSIPS? Unlike Asterisk, a typical OpenSIPS server is able to handle a very large number of simultaneous SIP calls. It is generally very reliable and will keep running for many months, or even years, with little or no attention. As a consequence, it is the preferred choice for many VoIP service providers who … Read more

Asterisk behind NAT

Scenarios in which NAT may adversely affect Asterisk SIP connections The Asterisk Server is behind NAT The Asterisk server could be on the LAN (or in a DMZ) with a NAT firewall between it and the Internet. When it communicates with external peers or devices, the network connections have to pass through the local NAT … Read more

Using SIP Devices behind NAT

SIP Devices behind NAT: What solutions are available? When an IP phone is installed behind NAT, problems can be created by the NAT device itself, by the phone’s inability to correctly understand its own networking environment or from a combination of the two. Because it is such a common problem, most IP Phones have built-in … Read more

High Availability and Failover options for SIP and Asterisk

Overview What’s the disaster we are trying to avoid? The assumed scenario is this: Some kind of centralised VoIP service is being offered to a number of users; the service operates on servers located at a data centre or office and the users each have a SIP client device, such as an IP phone, that … Read more