About IP Packet Communications – TCP and UDP
Devices communicate data to other devices on the Internet using certain recognised protocols that involve routing and transmission of packets of data to a remote device identified by an IP addresses....
View ArticleHigh 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...
View ArticleSIP and NAT: Why is it a problem?
Why is it a problem using SIP Clients behind NAT? What is NAT? To understand why SIP Clients behind NAT are a problem, you need to first have some understanding of what NAT is and what it does. NAT...
View ArticleUsing 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...
View ArticleAsterisk 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...
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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...
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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...
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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...
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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...
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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...
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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...
View ArticleHigh 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...
View ArticleSIP and NAT: Why is it a problem?
Why is it a problem using SIP Clients behind NAT? What is NAT? To understand why SIP Clients behind NAT are a problem, you need to first have some understanding of what NAT is and what it does. NAT...
View ArticleUsing 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...
View ArticleAsterisk 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...
View ArticleClik here to view.
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...
View ArticleClik here to view.
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...
View ArticleClik here to view.
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...
View ArticleClik here to view.
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...
View ArticleClik here to view.
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...
View Article
