Network Infrastructure Preparing your Network for IP Telephony

Introduction Faramarz Mahdavi Pylon founded in 1999 President/CEO Pylon Solutions My IP Telephone Pylon founded in 1999 IP-PBX VAR – 3Com, Avaya, Cisco My IP Telephone founded in 2002 IP-PBX Applications and Accessories Booth #501

Today’s Discussion Network Preparation for VoIP Power Requirements LAN WAN Remote Access Power Requirements Back-end power Power to IP Phones Roles and Responsibilities Vendor Selection and Support

Primary Points There is no particularly special network design for VoIP, but VoIP forces you to design your network properly. In order to deploy and maintain a successful IP-PBX system, you must not only have a network that is converged, but an IT organization that is converged. You must also ensure that the vendor who is providing your support and maintenance is a converged vendor.

Cabling Cabling requirements for 10mb and 10/100mb IP Phones are the same as PCs Category 3 cabling for 10mb phones Category 5 cabling for 10/100 phones Are you connecting your PC to the phone? If yes, go with Cat5e or better cabling If no, Cat3 or better for 10mb phones and Cat5 or better for 10/100 phones.

Cabling (2) Should you share one cable for both PC and phone? For companies with less than 35 phones, sharing one wire is fine, but be sure to purchase 10/100 IP phones. For companies with greater number of phones, any of the following options are fine: Physically separate the phones from PCs, with the option to use cheaper 10mb phones Daisy-chain your PCs behind the phones, but make sure your phones are 10/100 phones and can be separated via VLAN.

Cabling (3) New Buildings Make no distinction between voice and data runs Not on the type of cable Not on labeling of ports Not on termination on patch panels Treat voice and data exactly the same. For FAX, Modem, and other services, use the patch panels and cross-connect using the straight-through Cat5e runs to the station outlets.

Local Area Network Network Core Mid to Large networks need to adhere to the Core/Distribution principles. Redundant core with high bandwidth trunks to distribution switches Layer 3 switches vs. Edge routers Keep the edge routers at the edge KISS – “Keep It Simple Sunshine” Not necessarily inexpensive, but simple

LAN (2) For small networks: You don’t need redundant core switches, but you need to address fast replacement and recovery A good maintenance plan with rapid parts replacement Spare switch Available budget to purchase another switch if necessary

LAN (3) Medium to Large Networks Redundant Core For mid-size networks with limited budget, purchase chassis-based switch with redundant power supplies, and either a redundant processor or a spare hot-swappable processor. For larger networks, have two core switches with high-speed connectivity between them. Make sure that your IP-PBX can take advantage of the dual switch core with the ability to connect to both switches.

LAN (4) Layer 3 Switches with VLANs All layer 3 switches provide VLAN support Route between VLANs using wire-speed Layer 3 switches. Using Edge routers for VLAN routing slows down the network and depending on your traffic could be a bottleneck. Place all phones on a dedicated VLAN, whether you are sharing physical cabling with your data network or not. If sharing cabling, your phones must support VLAN tagging. Networks smaller than 35 phones can share physical cables and VLANs, but it is not recommended.

Power Options to feed power to IP phones: AC Adapter locally connected to the phone Power Source appliance in the wiring closet interface between the switch port and the phone Ethernet switches with in-line power

Power (2) Ethernet Power Power can be fed through the Cat5 cable using available pairs not used by Ethernet Standard vs. Proprietary IEEE 802.3af Different manufacturers have different methods, but the direction is towards the 802.3af standard

Power (3) How do decide whether to centralize power? Centralized power provides continued phone services during a power outage, but do you need it? Can your users operate even without PCs? Do customers actually need to reach employees live, or is voicemail access enough?

Power (4) Other Considerations: Power Over Ethernet is not an all or none option; you can just provide central power to a select group of users. For some it just a cosmetic decision to reduce the number of cables connected to the phone. Conference Rooms, Lobby, etc.

WAN QoS is most critical on the Wide Area Network Especially if you plan to use the Internet Prior to deploying VoIP across your WAN, you must conduct a thorough cost/bandwidth analysis With today’s low long-distance rates, it is often not worthwhile to deploy VoIP across the WAN. Good for international WAN links Determine the acceptable quality level for your usage. Will customers be calling across the link? Is it mainly intra-company calling primarily to reduce cost?

WAN (2) Networking Voice Calls vs. Networking Voicemail An important consideration for multi-site organizations is whether they are interested in live calling between offices, or if they just want a company-wide voicemail network. Voicemail networking does not require QoS since it is simply data file transfers. Live calls require acceptable bandwidth and latency.

WAN (3) IP Overhead Latency G.711 G.729A G.723.1 64kbps, but 198kbps with overhead G.729A 8kbps, but 115kbps with overhead G.723.1 6.4kbps, but 45kbps with overhead Latency General rule of thumb is to keep latency below 150ms

WAN (4) WAN Applications Multi-site business offices Trunk-side VoIP from one switch to another Telecommuter or very small branch offices IP Phones at the remote site with dial-tone from HQ xDSL or Cable connectivity Voicemail networking VPIM

Organization A single converged network requires administration and accountability from a single IT organization. Many companies split the roles, but it is not recommended VoIP requires knowledge of IP: routing, switching, DHCP, TFTP, ARP, etc. etc. Does the telecom guy disappear? NO. There is still need for people who know telephony features and applications. There just needs to be collaboration and cooperation.

Vendor A converged network also requires a vendor that understands convergence, not just telephony. Be sure to examine your vendor’s overall IP-PBX knowledge, including routing and switching. Most IP-PBX issues have to do with infrastructure. Make sure you build a solid infrastructure before deploying IP Telephony. Make sure you and your vendor are knowledgeable in IP and data network infrastructure troubleshooting in order to properly maintain an IP-PBX system.

Summary A successful IP-PBX installation is 80% infrastructure, so make sure your network is properly designed and prepared for voice. A converged network requires a converged IT organization to best maintain it. Lastly, a converged network and team need to be supported by a converged vendor.

Questions?