Transcript E-8 - TMCnet

Network Infrastructure
Preparing your Network for IP
Telephony
Introduction
• Faramarz Mahdavi
– 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
– 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 multisite 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
– G.711
• 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 dialtone 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?