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VOIP
20 years 5 months ago #4201
by jhun
hi to all...
well i haven't seen any new post here regarding the subject...i hope that you could share some light on the subject...well to start of can anyone provide me with some resources, insights and ideas regarding the installation of a VOIP system, the basics and also some advance teachings (e.g. commands used w/in the system). Any help would be very much appreciated....thanks a million...to the whole Firewall League....KUDOS!...youre all doing a great job
well i haven't seen any new post here regarding the subject...i hope that you could share some light on the subject...well to start of can anyone provide me with some resources, insights and ideas regarding the installation of a VOIP system, the basics and also some advance teachings (e.g. commands used w/in the system). Any help would be very much appreciated....thanks a million...to the whole Firewall League....KUDOS!...youre all doing a great job
20 years 5 months ago #4204
by Chris
Chris Partsenidis.
Founder & Editor-in-Chief
www.Firewall.cx
Hi Jhun,
VoIP is certainly a big and 'new' topic that we will be covering here at Firewall.cx, but not anytime soon. While I am certainly new to this area, I've been getting some great experience with the technology here at my office and I'll be putting down on paper to produce another quality topic.
While I won't be able to cover your question with one post, I'll just briefly outline what the technology is all about as a small introduction based on my current knowledge.
VoIP (Voice Over IP) allows users to communicate via phone, using the exisiting network infrustructure, rending the ordinary and expensive analogue/digital phones useless (in most cases).
Of course VoIP requires special phones that connect to your network via a classic RJ-45 straight into your switch. Your voice is coded and compressed (depending on how you configure the service) and sent on the network in form of Ethernet Packets, just as if two computers were talking on the network.
Each IP Phone device has an IP Address and is treated as a single host on the network, just like any computer. In most cases, the IP Phones are configured to obtain an IP Address automatically and once that phase is complete, they will send a special broadcast message, looking for a server to connect to .... this is where the term "Call Manager" comes into place. Cisco, being the leader on most networking technologies (VoIP is no exception) has come out with a wonderful product called the 'Cisco Call Manager'.
This service runs on a standard Windows 2000 platform and manages all IP Phones. Using the Call Manager Web Interface, you configure each IP Phone to a extention of your choice and also assign any details such as the user the IP phone belongs to and various other settings.
At the same time, if your using DHCP, you need to create a specific scope for the IP Phones.
All phone calls made within the network use the Call Manager, who will connect the two or more IP Phones wishing to establish a call. Think of the Call Manager as the central PABX System in a normal call center to help you get the idea.
The important bit reagarding IP Phones is QoS - Quality Of Service. Because the IP Phones are very sensitive to delays, you must apply Quality Of Service to your network in order to give priority to your Voice Packets, otherwise you will experience problems with delays and the voice-cutting effect while in a call.
At its best, Voice Over IP works like a charm when integrating it with a Cisco powered network, allowing you to implement the VoIP service in a network of its own (VLAN), to minimise any impact from the normal network everyone works off.
Combining VoIP with a network with Cisco Switches that utilise VLANs and QoS, you are guaranteed a rock solid Voice system that will not produce any problems.
Here at the office, we have over 300 IP Phones, two Call Managers (One backup), running over a 350 node network with more than 15 VLANs. It's perhaps one of the biggest implementations in Greece and I can tell you from first hand .... Cisco VoIP rocks
Cheers,
VoIP is certainly a big and 'new' topic that we will be covering here at Firewall.cx, but not anytime soon. While I am certainly new to this area, I've been getting some great experience with the technology here at my office and I'll be putting down on paper to produce another quality topic.
While I won't be able to cover your question with one post, I'll just briefly outline what the technology is all about as a small introduction based on my current knowledge.
VoIP (Voice Over IP) allows users to communicate via phone, using the exisiting network infrustructure, rending the ordinary and expensive analogue/digital phones useless (in most cases).
Of course VoIP requires special phones that connect to your network via a classic RJ-45 straight into your switch. Your voice is coded and compressed (depending on how you configure the service) and sent on the network in form of Ethernet Packets, just as if two computers were talking on the network.
Each IP Phone device has an IP Address and is treated as a single host on the network, just like any computer. In most cases, the IP Phones are configured to obtain an IP Address automatically and once that phase is complete, they will send a special broadcast message, looking for a server to connect to .... this is where the term "Call Manager" comes into place. Cisco, being the leader on most networking technologies (VoIP is no exception) has come out with a wonderful product called the 'Cisco Call Manager'.
This service runs on a standard Windows 2000 platform and manages all IP Phones. Using the Call Manager Web Interface, you configure each IP Phone to a extention of your choice and also assign any details such as the user the IP phone belongs to and various other settings.
At the same time, if your using DHCP, you need to create a specific scope for the IP Phones.
All phone calls made within the network use the Call Manager, who will connect the two or more IP Phones wishing to establish a call. Think of the Call Manager as the central PABX System in a normal call center to help you get the idea.
The important bit reagarding IP Phones is QoS - Quality Of Service. Because the IP Phones are very sensitive to delays, you must apply Quality Of Service to your network in order to give priority to your Voice Packets, otherwise you will experience problems with delays and the voice-cutting effect while in a call.
At its best, Voice Over IP works like a charm when integrating it with a Cisco powered network, allowing you to implement the VoIP service in a network of its own (VLAN), to minimise any impact from the normal network everyone works off.
Combining VoIP with a network with Cisco Switches that utilise VLANs and QoS, you are guaranteed a rock solid Voice system that will not produce any problems.
Here at the office, we have over 300 IP Phones, two Call Managers (One backup), running over a 350 node network with more than 15 VLANs. It's perhaps one of the biggest implementations in Greece and I can tell you from first hand .... Cisco VoIP rocks
Cheers,
Chris Partsenidis.
Founder & Editor-in-Chief
www.Firewall.cx
20 years 5 months ago #4205
by jhun
WOW!!!...thanks chris for that very informative post on the subject. i never imagined that VOIP could be utilized to produce great effects on the network architecture...and by the way my hat's off to you for a wonderful network on your workplace and great implementation of the VOIP system. i can't wait for an article to be posted here at firewall. i'll bet many would want that as well..again many thanks.
20 years 1 month ago #5418
by nske
Voice with VoIP technology is, physically, no different than any IP data. The only thing that needs attention is what Chris said, that it is very important that the data packets for VoIP take absolute priority over any other packets, to avoid delays and/or interruptions in the flow. As for the bandwidth requirements, voice can be lossly compressed in huge ratios with no annoying practical loss in quality. In practice, 14kbps in average should be enough for each call. Also notice that the bandwidth is dynamically allocated, only used when there is actually something to transmit (i.e. only when someone is speaking). Thus VoIP needs can be satisfied just fine by today's high-quality ethernet networks.
If voice and data will run through it will it create terrible network traffic?
Voice with VoIP technology is, physically, no different than any IP data. The only thing that needs attention is what Chris said, that it is very important that the data packets for VoIP take absolute priority over any other packets, to avoid delays and/or interruptions in the flow. As for the bandwidth requirements, voice can be lossly compressed in huge ratios with no annoying practical loss in quality. In practice, 14kbps in average should be enough for each call. Also notice that the bandwidth is dynamically allocated, only used when there is actually something to transmit (i.e. only when someone is speaking). Thus VoIP needs can be satisfied just fine by today's high-quality ethernet networks.
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