What are basic networking and architectural requirements of Voice over IP solutions you should consider? Find more…
General requirements of VoIP solutions
Appropriate measures have to be taken to provide high quality interactive voice and video communication services over data networks. The following chapter lists a few of them without going into detail (you may download relevant standards dealing with the details from ITU-T or IETF). Please consider the details of the standards when you design and plan your high quality Voice over IP (VoIP) solution.
It is recommended for each workplace to install a minimum of 2 separated twisted pair telecommunications outlets for the data network (no specific requirement of VoIP solutions but a recommendation of standards describing structured cabling system).
Network Parameters for Voice over IP
Network parameters like packet loss, delay and jitter need to be monitored to guarantee sufficient voice or video quality. Find required parameter values in ITU-T G.114, IETF RFC 2212 or other documents.
Switches and Routers, WLAN Access Points
LAN switches and routers should support prioritization technology (such as IEEE 802.1D or Differentiated Services) and „Power over Ethernet“ (PoE).
WLAN Access Points should support prioritization in their radio interfaces.
Internet Protocol Version 6 (IPv6)
All voice and video devices (IP phones, adapters, servers, gateways, etc.) should support IPv6 even if you are not planning to implement IPv6 in the near future.
The power supply units of the switches have to handle the total amount of power consumption (including power requirements of end devices)
The increased heat dissipation of the power supplies may require an air-condition upgrade for the racks.
Redundancy and Reliability
Redundancy and reliability of cabling, switches and routers, servers and other components are very important considerations.
Virtualization of switches, routers or servers offers more flexibility but adds complexity of the solution.
Emergency operation of the telephony solution (emergency calls, alarm systems and alarm server integration and similar things) has to be considered.
A separation into different physical or virtual networks, one for IT applications and one for telephony, is not recommended (how would you separate a telephone call made from a desktop computer running a softphone in a web browser window and a second window is used to retrieve data stored in a web server?).
Examples of reasons:
- Signalling protocols in VoIP are implemented proprietary or vendor independent (associated to layer 5 or higher according to the ISO/OSI model)
- IP phone sets use IT services like DNS, FTP, TFTP, DHCP, user directory services and others. These are standardized and already managed services in every IT solution.
- Besides telephony many other services have to be offered like Instant Messaging, video exchange, presence state indication and much more, provided by application-oriented protocols of the TCP/IP (and Internet) world.
- All devices (IT, telephone sets) use Ethernet.
- All elements may be managed together (fault management, device management, configuration management, performance management, security management, eventually expense management).
VoIP Readiness Test
Tipp: test (or let test) your network (end-to-end) for VoIP readiness before you start to plan your solution, maybe the test results show up some troubles you should solve before you start your VoIP project!
Tipp: ask your service provider to test your network under predicted heavy load to find bottlenecks or time-out problems in your existing applications.
Any questions or suggestions? Please leave me your comment.
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About the Author
Ronald Schlager is independent trainer, consultant, author and blogger with main emphasis on communications technologies and their applications.