[VoiceOps] What is the State of the Art in VoIP Network Design?

[Mark R Lindsey]

It's best for the Science and Art to have a public discussion about VoIP network designs. What was once an incidental installation task is often recognized as a key activity with serious cost implications. But still, many networks are never designed -- they just happen. IP Networks do not -- by default -- work well for VoIP.

We the industry should document the current state of the art for the design of VoIP Networks. The need is greatest in carriers and large enterprises networks, but the design of networks for VoIP at all scales is interesting.

Please help me document the standard industry practices in VoIP Network Design, both of new networks and also the expansion and evolution of existing networks. Your responses will be analyzed and compiled into a publication that will be submitted for conference publication.

I hope to hear from vendors such as Acme Packet, Audiocodes, BroadSoft, Cisco, Digium, Genband, Metaswitch, Sonus, Taqua, and others. But I especially want feedback from individual designers & integrators.

Everything you provide will be published online and credited. 

Responses received by February 15, 2011 will be used for the paper submission.

My employer, ECG, Inc. is a for-profit entity, but this project is NOT a commercial enterprise. We wish to foster and sponsor innovation in VoIP networks in an open, free academic dialog.

Mark R Lindsey, ECG Inc.
mark at ecg.co  |  +1-229-316-0013  |  http://ecg.co/lindsey


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VoIP Network Design Survey. 
Please respond to lindsey at e-c-group.com



A. If you would be willing to submit reference network designs for publication, please send them in PDF format. [VNDS1-A]



B. Please provide answers to the following questions -- as much as possible. Even if you only have time to answer one question. [VNDS1-B]



Q-1. What application-layer (VoIP) network devices do you regularly design with? What are special network requirements of each device? [VNDS1-B-1]



Q-2. Where do you use public IP addresses, and where do you use private IP addresses? In each case: why do you use that type of address? [VNDS1-B-2]



Q-3. How do you handle customer-premise access devices behind NAT? [VNDS1-B-3]



Q-4. How do you handle peering ("SIP trunks") between carriers? (e.g., SBC? Separate IP assignment per endpoint? Separate Port assign nment? Authentication?) [VNDS1-B-4]



Q-5. How do you guarantee network capacity for VoIP Media traffic? ...for VoIP signaling traffic? [VNDS1-B-5]



Q-6. Are you designing to support SIP over TCP or SCTP? If so, why? If not, do you address fragmentation of large SIP? [VNDS1-B-6]



Q-7. How do you describe your approach to network security boundaries?  How do you enforce these boundaries? (Common approaches: firewalls, SBCs, VRFs/routing domains, server packet filters, private IPs and routing policies, etc.) [VNDS1-B-7]



Q-8. What are the key security or operational threats that you design to protect against? [VNDS1-B-8]



Q-9. What are the key network design principles for VoIP Networks that you follow? [VNDS1-B-9]



Q-10. What are the key mistakes you try to avoid in VoIP Network design? [VNDS1-B-10]



Q-11. What future trends in network design and requirements do you anticipate? [VNDS1-B-11]



Q-12. What are your tightest constraints in your network designs? (e.g., Design time? Testing/Stability/Change Control? Rack space? Network link capacity? Money? CPU Capacity? CAM space?) [VNDS1-B-12]