VoIP

Bakedgoods

Bakedgoods

Bakedgoods

Capodecina
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Can anyone recommend any sites/reading material for a basic introduction to relatively large VoIP implementations and how the infrastructure etc is structured?

All the VoIP stuff I seem to find is talking about using a PC for phone calls, which is not what i'm after at all.
 
You'll find it largely depends on the equipment you use, different companies have different architectures for their VOIP offerings.

There are basically two schools of thought, the old pbx companies who adapted and made their products ip enabled and the networking companies who built ip pbx's from scratch.

I'm not a voice engineer, I have some experience with cisco stuff (enough to set up an office on CCME with unity) and it's pretty good. Because cisco came from the networking side there are a few telephony functions which should be easy to setup which aren't but generally you can do what you need to with it.

Trouble is, I find the cisco documentation very hard to get into when it comes to VOIP. There are come cisco press books around on the subject but they generally assume some knowledge.

Also depends what you mean by large scale, cisco VOIP really scales and the cost really adds up, you can get to £50k+ just for a switch on some implementations...
 
That's not a problem, everything else here is Cisco.

It's a massive project but it's likely to take place eventually. I'm just trying to get a basic understanding of how an infrastructure is setup for similar size implementations. For example, what sort of switches are used at access and distribution etc, does it go out through your usual router or a special telephony router and so on.

I really haven't got a clue about VoIP so i'm not too interested in the technical details, but a basic overview.

Thanks you've been a big help with a number of my questions :)

I'll have a look at the case studies shortly.
 
The implementation of cisco voip is generally very compelx unfortuantely. The complexity has some upsides, it gives you an architecture where voip and data use the same network infrastructure but it means you have to implement QOS very well.

Security is also a nightmare for voip installations, people are starting to pay more attention to it now. You need low latency traffic inspection and firewalling which gets expensive - Cisco 6500 switches with IDS and Firewall blades are popular for the job. (I have a few in the lab for a project and they cost £60k each)

Generally you'll beef up the switch architecture a bit, maybe using 3750 stacks as access/distribution switches (or even 4500s in big sites), making sure you're applying QOS from the access layer onwards and routing all the traffic together in the core.

For implementations of that size the full blown callmanager is needed, it runs on Cisco MCS servers (which inspite of the name as simply rebadged HP and IBM x86 servers).

Remote sites have two options, either connect to the main callmanager direct and have a SRST router on site (which will take over call handling if the link to the central site goes down, you'll loose advanced features but can still call people - SRST will run on most of the cisco integrated services routers).

Second option is to run a callmanager express on a ISR and create a trunk to the main callmanger with PSTN fallback. Good for sites with low bandwidth but means you have no central easy to manage platform.

It requries really careful network design for big installations, mainly because QOS must be flawlessly configured.
 
We're already aware the edge and distribution layer switches will need replacing/upgrading (power over ethernet requirements).

So you basically have a 'Phone router' in the simplest terms? I'm just not too sure how it all comes together at the top.

I understand the phone > switch part but it's the VoIP hierarchy I don't have a clue about. I assume it's kept seperate from the PC network at acess layer but makes use of the existing distribution switches and core routers?

Where exactly does the call manager sit in terms of the network topology? I'm guessing it's main purpose is assinging/registering extension numbers and handling voice mail (or does the handset store the voice mail?)

Thanks again :)

I've got so much to learn at the moment, trying to study CCNA whilst developing a system and researching several different technologies.
 
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Have a look at the Cisco SRND Guide For Unified Communications. I will warn you if you haven't had experience with Cisco or Voip it may well hurt your head.

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/6x/uc6xsrnd.pdf


Ill be honest i would contact Cisco and ask to be contacted by a channel partner, if you are correct and want to service 3000 users it's a mammoth project.

Regards
 
I wouldn't be doing any of the technical work myself, i'm just trying to get an understanding from a high-moderate level.

I do have some cisco experience (learning CCNA), i'll do some reading now.

Thanks :)
 
Can't tell you much about Cisco CM as we're a Siemens house but for infrastructure, you can build things several different ways. Building a parallel VoIP platform for 3000 users won't be cheap though, so I would expect partial or total integration into the existing infrastructure through the use of VLANs, QoS etc etc.
 
Wardie said:
I wouldn't be doing any of the technical work myself, i'm just trying to get an understanding from a high-moderate level.

I do have some cisco experience (learning CCNA), i'll do some reading now.

Thanks :)
Click to expand...

Thats not a problem, the document above should help you understand the structure of such a deployment, are these users located at a single site or multiple sites?
 
Youll probably be looking at IP links with optional PSTN backups at the remote site in case the WAN links drops and centralised call processing in the way of a Call Manager Cluster at the main site. HQ connectivity could vary depending on your needs, i imagine due to the size it would be something significant upwards of a 100Mb Leased Line.
 
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