IP over Voice

8/7/2019 IP over Voice

1/31

IP over Voice: Transmitting Data Over an POTSNetwork and VOIP

Masters Project ReportMay 2003

AdvisorProf. Ausif MahmoodAssociate Professor

Dept. of Computer Science & Engineering

University of Bridgeport


2/31

Submitted byParth DaveS.Id 459802

Contents

Abstract & Introduction 3

1) Overview of the PSTNA) The Beginning of the PSTN 4B) Drawbacks to the PSTN 4

2) VOIP: Transmitting Voice Over an IP NetworkA) What is VOIP? 5B) Why do we need Voice over IP? 5

C) A Basic VOIP System Architecture 6

3) Identification of major system components 6

4)VOIP product development issues 8

5) Protocols for VOIP 12

6) Four ways to do VOIP 13A) Gateways: popular, but lack featuresB) IP PBXs: great features, scalability lacking

C) Converged appliances: simplified managementD) Other options: mix and match

7) VOIP SERVICES 15A) PC to Phone ServicesB) PC to PC servicesC) Phone to Phone ServicesD) Network Services

8) Data over POTS Case Study: Hotel Internet Access 17

9) Frequently Asked Questions (FAQ) 22

Conclusion 29

Masters Project Parth Dave2


3/31

References / Books 29

WebPages 30ACKNOWLEDGEMENTS

I sincerely thank Prof. Ausif Mahmood for his invaluable guidance and supportthrough the course of my project.

Abstract

With massive advances in technology the computational power available to us

has increased manifold. As a result of this it has become possible for us totransmit data over Plain Old Telephone System (POTS), which is a circuit-switched network, and voice over an IP network, which is a packet switchednetwork. Since voice traffic maps directly to a circuit switched network, and not,onto a packet switched network therefore to be able to transmit voice data over apacket switched network entails several complications, which must be dealt withbefore we can use the Internet for transmitting real time audio traffic.This project covers the basics of a VOIP network and the current marketproducts and trends. The purpose of this paper is to study some of thesecomplications namely delay, packet loss, jitter, encoding and to present some ofthe solutions to these problems. This is a broad overview of VOIP and is meantto give the reader an idea of the issues involved in trying to cater to voice trafficin an IP network.

Introduction:

In this paper I shall present a broad overview of the different complications thatarise in trying to provide Data over POTS and Voice traffic in the current Internet.The reason why these complications arise is due to the fact that voice traffic has

certain differing characteristics and requires much more stringent Quality ofService Guarantees.We begin this paper by explaining what we mean by VOIP, and then we go on todiscuss whether it is wise to cater for voice traffic in a packet switched network inthe first place. We then describe a basic VOIP architecture and describe itsworking. Then we go on to analyze the various characteristics of voice traffic,which need to be taken into account when we discuss its transmission in a



4/31

packet switched network. In this section we discuss its delay properties,temporal properties, response to packet loss, bandwidth management, encoding,jitter, silence suppression and echo cancellation. We shall present how all thesecharacteristics present a problem in voice transmission in an IP network and howthey may be provided for by employing certain mechanisms.

The Beginning of the PSTN

The Public Switched Telephone Network (PSTN) has been evolving ever sinceAlexander Graham Bell made the first voice transmission over wire in 1876. Theexisting PSTN does not fit all the needs of its builders or users. After youunderstand where todays PSTN is lacking, you will know where to look to find asolution. This section sets the stage for why the voice and data networks aremerging into a single network.

Drawbacks to the PSTN

Although the PSTN is effective and does a good job at what it was built to do(that is, switch voice calls), many business drivers are striving to change it to anew network, whereby voice is an application on top of a data network. This ishappening for several reasons: Data has overtaken voice as the primary traffic on many networks built forvoice. Data is now running on top of networks that were built to carry voiceefficiently. Data has different characteristics, however, such as a variable useof bandwidth and a need for higher bandwidth. Soon, voice networks will run ontop of networks built with a data-centric approach. Traffic will then bedifferentiated based upon application instead of physical circuits. New

technologies (such as Fast Ethernet, Gigabit Ethernet, and Optical Networking)will be used to deploy the high-speed networks that needed to carry all thisadditional data. The PSTN cannot create and deploy features quickly enough. Data/Voice/Video (D/V/V) cannot converge on the PSTN as currently built.With only an analog line to most homes, you cannot have data access(Internet access), phone access, and video access across one 56-kbpsmodem. High-speed broadband access, such as digital subscriber line (DSL),cable, or wireless, is needed to enable this convergence The architecture built for voice is not flexible enough to carry data.

It is also important to note that circuit-switched calls require a permanent 64-kbpsdedicated circuit between the two telephones. Whether the caller or the personcalled is talking, the 64-kbps connection cannot be used by any other party. Thismeans that the telephone company cannot use this bandwidth for any otherpurpose and must bill the parties for consuming its resources.Data networking, on the other hand, has the capability to use bandwidth onlywhen it is required. This difference, although seemingly small, is a major benefitof packet-based voice networking.



5/31

What is VOIP?

We must begin by discussing what is Voice over IP? By voice over IP we meanthe transmission of real time voice signals over an IP network namely theInternet. The question then arises that what is the big deal in transmitting voicesignals over a packet switched network? Well if we look closely at the underlyingarchitecture of the Internet, it becomes apparent that to be able to provide voiceservice over an IP network needs a lot of different mechanisms to be built intothe IP networks and also in the end hosts. The reason for this is that the servicerequirements of VOIP dont map onto the Internet in an inherent way. The currentfor this is that current Internet provide only best effort service, whereas Voicetransmission over the Internet require much more stringent guarantees from theInternet. As a result of which we need to build mechanisms over the currentarchitecture to provide these services to the voice applications. The specificrequirements and characteristics of Voice traffic are discussed later in the paper.We must mention here the difference between multimedia voice transmissionand voice transmission over IP. By VOIP we mean real time voice transmission.The voice signal at the sender is encoded and sent to some receiver where thereceiver immediately replays the packets as soon as it receives it. All thishappens in real time. Whereas in a multimedia system, the receiver may receivethe whole voice segment and store it locally and then play it back whenever theuser requests it. The analogy would be something like a voice telephone call witha voice mail.

Why do we need Voice over IP?

We mentioned that voice traffic has characteristics which are different fromtraditional traffic carried by the Internet and to provide for voice traffic is not atrivial issue. Then the natural question is whether we should carry voice traffic inthe Internet in the first place? After all we already have a telephone system inplace, why do we need to transmit voice over the Internet? The answer to thislies in the massive advantages which can be achieved from multiplexing voiceand the traditional data traffic. The inherent nature of both this type of traffic issuch that their presence on a single wire is both complementary. One can justimagine the massive cut in spending, we could have long distance calls at theprice of local ones. In the current telephone network, currently when we place acall, the required bandwidth is reserved for the entire path for the duration of thecall and even if the speaker is not saying anything, the bandwidth is still lockedwith that person and no body else can use it. As a result of this, for a given



6/31

bandwidth, without statistical multiplexing, the total number of users that can besupported is much less than of we could use statistical multiplexing .

The advance in technology, both in the network and in the end host, allows us toempty encoding techniques and time stamping and sequencing without incurring

too much delay so that voice can be transmitted to the other side with acceptabledelays. There are various value added services that can be provided if we usethe Internet for voice transmission. Thus weighing the pros and cons it clearlystands out that there are massive advantages to be had from integrating voice inan IP network .

A Basic VOIP System Architecture:

A basic VOIP architecture would have a host where the voice signal must becompressed, coded and inserted into packets, have a sequence number andtime stamps and sent to the receiver where they must be received and stored in

a payoff buffer and then the signal recreated based on the time stamps andrelative positions of things. VOIP services architecture either be PC-PC or PC-phone or vice versa. A basic of scenarios of voice over IP in the PC-PCarchitecture may be that voice signals at some host are encoded as soon as theyare produced and are sent to the remote machines IP where the remote machineon receiving the packet decodes the packet and sends it immediately to theprocess. An alternative scenario might be a PC calling a remoter telephone. Wespecify the telephone number and the remote telephone numbers are mapped toIP address of the gateway closest to the receiver. The sender address the IPpackets to remote gateways IP and remote gateway on receiving the packetsdecodes them and sends an analogue signal to the remote telephone. Similarly

in the telephone-PC architecture the gateway would do the packetization andencoding of data in packets.

IDENTIFICATION OF MAJOR SYSTEM COMPONENTS

1 Gateway

The gateways are the devices that communicate between the telephone signalsand the IP endpoint. The IP endpoint usually speaks H.323 for media stream andmore recently Session Initiation protocol (SIP). The gateways usually performthe following 6 functions

Search function

When an IP gateway is used to place a call across an IP network, itreceives a called party phone number. It converts it into the IP address ofthe far end gateway, possibly through a table lookup in the originatinggateway or in a centralized directory server.



7/31

Connection Function

The originating gateway establishes a connection to the destinationgateway, exchanges call setup, compatibility information and performsany option negotiation and security handshake.

Digitizing function

Analog telephone signals coming into a trunk on the gateway are digitizedby the gateway into a format useful to the gateway, usually 64 kbps PCM.This requires the gateway to interface to a variety of Telephone-signaling

conventions.

Demodulation functions

With some gateways the gateway trunk can accept only a voice signal ora fax signal but not both. But sophisticated gateways handle both. Whenthe signal is a fax, it is demodulated by the DSP back into the original 2.4-14.4 kbps digital format. This is then put into the IP packets fortransmission. The demodulated information is remodulated back to theoriginal analog fax signal by the remote gateway, for delivery to theremote fax machine.

Compression functions

When the signal is determined to be voice, it is usually compressed by aDSP from 64K PCM to a 5.3 Kbps signal.

Decompression and Remodulation functions

At the same time that the gateway performs steps 1-5, it is also receiving

packets. Hence this function is required

2 Gatekeepers

Terminals are the LAN client endpoints that provide real time two-waycommunications. When an endpoint is switched on, it performs a multicastdiscovery for a gatekeeper and registers with it. Thus the gatekeeper knows howmany users are connected and where they are located. The collection of a



8/31

gatekeeper and its registered endpoints is called as a zone. A gatekeeper isrequired to perform the following functions:

Address translation

Translation of an alias address to a Transport Address using a tableupdated via Registration messages.

Admissions control

Authorization of LAN access, using Admissions Requests or Confirm andReject (ARQ/ARC/ARJ) messages. Access is based on call authorization,bandwidth or some other criteria.

Bandwidth management

Support for Bandwidth Request, Confirm and Reject messages, or a nullfunction that accepts all requests for bandwidth changes.

Zone management

The Gatekeeper provides the above functions for terminals, MCUs, andGateways, which are registered in its Zone of control.

3 IP Telephones

These are devices, which replace the existing telephones by providing enhancedservices suited to VOIP. At the same time they should retain the capabilities ofthe original phones to keep the user comfortable.

4 PC Software phones

This arrangement consists of a microphone connected to a PC interfaced by acard and running a software, which permits voice and multimedia transfer overthe Internet. Microsoft NetMeeting is an example.

VOIP PRODUCT DEVELOPMENT ISSUES



9/31

In this section we discuss the points that manufacturers have to take note ofwhile developing their products.

1 Voice Quality

The voice quality should be comparable to what is available using the PSTN,even over networks of varying levels of QoS. If a company thinks that reducingthe bills is the criteria and adopts a poor quality VOIP service, then the onlypeople using that service would be the Managing Director and the AccountingOfficer. The employees will not compromise quality to reduce the company'sbills.

The following factors decide the VOIP quality:

Use of a Quality CODECCodec stands for Coder Decoder. It should give good voice quality andlow delay. The International Telecommunication Union's (ITU's) officiallyrecommended CODEC for all wide area networking applications is G.729

Echo cancellationWhen a two-wire telephone cable connects to a four-wire PBX interface ora Telco central office interface, a special electric circuit called a hybrid is

used to do the conversion. But in them a small percentage of telephoneenergy is not converted but instead reflected back to the caller creating anecho. If the delay is more than 10mS the caller hears the echo and thishas to be avoided.

Delayo Total Transmission Delay

Total transmission delay is the sum of the compression,decompression delays, processing delay, the buffering/Queuingdelay, the transmission delay and the network delay. The networkdelay is variable while the others can be fixed pre hand to less than

130ms. When this total delay exceeds 200ms, the two speakershave to make sure that when one speaks the other listens andpauses to make sure that the speaker is done. Bad timing mayresult in stepping on the other's message.

o Delay Jitter

Delay jitter is the variability in arrival time of a packet. When apacket does not arrive in time to fit into the voice stream going out



10/31

of the far end gateway, it has to be discarded. It cannot be retransmitted, as it would delay proceedings too much. If thishappens too often, then the listener will perceive reduced voicequality.

o

Delay management VOIP Packet Prioritization

The reason VOIP works well over a corporate IP network isdue more to the corporate network's low jitter than low delay.Corporate routers usually prioritize voice/fax packets eitherby explicit programming of the router or by using aprioritization protocol like Resource Reservation Protocol(RSVP).

IP Packet SegmentationThis is an important step required to ensure that a very long

data packet does not delay the voice packet from exiting therouter in a timely manner. This is achieved by programmingthe router to segment all out bound data packets accordingto the WAN access link.

Packet replay techniqueTo allow for variable packet arrival time and still produce asteady outgoing stream of speech, at the far end the speechis not played as soon as the first packet arrives. Instead it isheld in the jitter buffer for some time and then played. Thisadds to the overall delay. The lesser the jitter, smaller the

jitter buffer time and lower the delay.

The combination of the above three techniques produces aVOIP friendly IP network. Such IP networks are called asManaged IP networks.

VOIP Forward Error Correction (FEC)The public Internet has substantial packet corruption and loss. Packetreplay may not suffice. For this FEC can compensate for the corrupted ormissing packet.

o Intra Packet FEC

Here extra bits are added, thus allowing the receiving end todetermine which of the bits were corrupted, yielding a packet readyfor play out.

o Extra packet FECHere extra information is added to each packet that allows the



11/31

receiving gateway to extrapolate from the previously received goodpacket and reconstruct the missing or severely corrupted packet

2 High Bandwidth Consumption

A telephone quality call or a toll quality call requires at least 64 kbps/call. Thisbandwidth is impossible to dedicate on a data network for voice.

Speech compression techniques as the G.729 reduce this to around 8kbps. TheIP router overhead is around 7 kbps. Thus it is 15 kbps. But moderncompressors make use of an important technique called as silencesuppression. In a typical full duplex phone conversation, only 35-40% is active.There are significant pauses between words, phrases etc. The bandwidth

consumption is thus reduced by silence suppression. Ultimately voice requiresonly 5-6 kbps.

Silence suppression renders the line absolutely silent to the listener so much sothat it sounds absolutely dead. But by inserting Comfort Noise or even better, byperiodically sampling the background noise and regenerating it for the listener,the line sounds active.

3 Transparency to the user

The user need not know what technology is being used for the call. He should be

able to use the telephone as he does right now.

Ease of configuration

An easy to use management interface is needed to configure theequipment. A variety of parameters and options such as telephonyprotocols, compressing algorithm selections, dialing plans, accesscontrols, PSTN fall back features, port arrangement etc. are to be takencare of.

Addressing / Directories

Telephone numbers and IP addresses need to be managed in a way thatit is transparent to the user. PCs that are used for voice calls, may needtelephone numbers. IP enabled telephones IP addresses or an access toone via DHCP protocols and Internet directory services will need to beextended to include mappings between the two types of addresses.

4 The TCP/UDP issue



12/31

The voice packet is constructed as a UDP/IP packet, to avoid TCP/IP's attemptto retransmit the corrupted packet. However TCP could be a better alternative forFax transmission simply because if lost packets occur during the negotiation of apage, the fax could be terminated. When TCP/IP is used and the host softwarehides the retransmission from the fax machine, there will be no impact.

5 Deployment of the Gateway: Trunk Contentions

At a remote site there are normally 2 to 4 VOIP connections (or trunks) from theVOIP gateway to the PBX allowing 2 - 4 simultaneous phone/fax connectionsbetween the remote site and other corporate locations. The actual number oftrunks depends upon the number of calls made per day and the total amountthey consume. The number of the head quarters trunks is decided by the totalnumber of phone calls between head quarters and the remote sites and the totalnumber of simultaneously active calls. Usually, head quarters have a fraction ofthe total trunk count. The trunk contention ratio is the ratio of total remote site

trunks to head quarter trunks.

6 Security

Authentication/ Encryption

VOIP offers the potential for secure telephony by making use of theservices available in TCP/IP environments. Access controls can beimplemented using authentication and calls can be made private using

encryption of the links.

Security implementation

Security features are usually implemented using four primary components:Packet Filtering Router, Connection gateway, Address Translating firewalland Application proxy.

Achieving security is a complex issue. An H.323 call is made up of manydifferent connections. In addition addresses and port numbers are

exchanged within the data stream of the next higher connection. Thismakes it particularly difficult for address translating firewalls, which mustmodify the addresses inside those data streams.

The firewall must be able to stand under a large number of simultaneousconnections also. Detection of intruders should be possible on the insideand the outside of the firewall.



13/31

7 Accounting / Billing

VOIP gateways must keep track of successful and unsuccessful calls. Call detailrecords should be produced. But the major issue is the suitable billing modelselection. A number of billing models have been suggested

Time-based - Metered by flow duration, time-of-day, time-of week Destination, distance, carrier-based IP - Rated by called and calling

station IDs associated with the sequence of stages used to support thecall

QoS-based Voice over IP - reflecting established service parameters suchas priority, selected QoS, and latency.

Protocols for VOIP H.323:

H.323 is a set of protocols for voice, video and data conferencing over packet-based networks such as the Internet. It is designed to operate above thetransport layer of the underlying network. This protocol assumes that no qualityof service is provided by LANs. H.323 defines four logical components which are:Terminals, Gateways, Gatekeepers and Multipoint Control Units(MCU). Theterminal, gateways and MCUs are known as endpoints. H.323 terminals are theLAN client endpoints that provide real time, two way communications. A H.323terminal can communicate with either another H.323 terminal, a H.323 gatewayor a MCU. An H.323 gateway provides for real-time, two-way communicationbetween H.323 terminal on the IP network and other ITU terminals on a switched

based network, or to another H.323 gateway. Their basic function is that of atranslator i.e. they perform the translation between different transmissionformats. The gateway is the interface between the PSTN and the Internet. Theytake voice from PSTN and put it on the public Internet and vice versa.Gatekeepers are the most vital part of H.323. A gatekeeper plays the role of amanager. It acts as the central point for all calls within its zone and providesservices to the registered endpoints. Gatekeepers also do bandwidthmanagement and controls admission of end points. The MCU is an endpoint onthe network that provides the capability for three or more terminals and gatewaysto participate in a multipoint conference. The MCU determines the capabilities ofeach terminal and sends each a mixed media stream. In the decentralized model

of multipoint conferencing, a MC ensures communication compatibility but themedia streams are multicast and the mixing is performed at each terminal.

Four ways to do VOIP



14/31

How to install voice over IP on your enterprise network. If you want to get startedtoday on a transition to voice over IP, there are four options: gateways, IPPBXs, converged appliances, and other.

1 Gateways: popular, but lack features

A voice-over-IP gateway can be loosely defined as a mechanism that takescircuit-switched voice from a traditional PBX, converts it to IP and transfers itacross a LAN or WAN to another gateway where it is reconstituted back into aformat that is understood by the receiving phone system.Gateway functionality can be obtained through stand-alone boxes, modules orchassis cards for proprietary boxes; also expandable routers or software andexpansion cards for Windows NT servers.For example, Cisco is taking a modular approach with a voice-over-IP card thatfits its 1750, 2600 and 3600 series routers. All Cisco products can easily beequipped for voice. Cisco says voice packets can be guaranteed via quality-of-

service policy implementation on a Cisco-switched network.Lucent, Nortel Networks and Siemens offer similar strategies for providing voice-over-IP gateway capabilities in some form or another.While gateways are the most popular voice-over-IP products on the market --available from at least 30 vendors -- the key point here is that you have voicepackets running over IP. However, the packets are not running on the Internet,and you're not gaining any of the features and capabilities you get by convergingvoice and data networks.

2 IP PBXs: great features, scalability lacking

IP PBXs, such as Altigen's AltiServe and Artisoft's TeleVantage, are great if youhave the luxury of designing your system from the ground up. IP PBXs arecomplete phone systems, usually with IP phone options that include many of theIP telephony applications, such as managing your phone from your desktop PC,multiline call control and automatic call distribution.IP PBXs are usually NT servers with telephony software and voice cards.Disadvantages often include scalability and a dial tone that's dependent on NT,which doesn't offer the same uptime as a switched phone network.Until recently, IP PBXs have mainly been targeted at small or branch offices with100 users or less, but Alcatel recently announced OmniPCX, a voice-over-IPsystem that incorporates gateway and call processing in a single device and canaccommodate up to 50,000 users. Additionally, 3Com, Lucent and Cisco have allannounced plans to provide the same type of product.Cisco's Selsius products and 3Com's NBX series fit in this category because thegoal of both is to provide the same services as OmniPCX on a large scale.However, while initial versions of these products are in trial stages, they have notbeen proven for high numbers of users. Alcatel is the first to stake that claim, andCisco and 3Com will have products in the future that compete. 3Com now saysits product is only for midsize businesses with less than 500 users.



15/31

The beauty of an IP PBX is being able to create a distributed system. Forexample, Nokia's IP Telephony Gateway and Shoreline Teleworks' ShoreGearIPBX allow you to distribute your phone system throughout an IP network, sogeographically separated phones -- with features such as direct dial, callforwarding, conferencing and voice mail -- provide the appearance of being

connected directly to the local PBX. Alcatel, 3Com's, Lukenss and Cisco's IPPBXs do not offer these features.

3 Converged appliances: simplified management

Converged appliances that join phone and data networks provide the simplifiedmanagement that fulfills the promise of voice over IP. Several vendors offer suchappliances. For example, Vertical Networks' Instant Office offers call services,voice mail, routing and LAN connect for voice and telecom, for a small to midsizeoffice, all included in the same box and managed together. Also, Praxon's PDX,a modular communications platform, combines voice PBX features with a full

complement of data networking, messaging and Internet functions.

4 Other options: mix and match

Aside from stand-alone gateways, IP PBXs and converged appliances, there'sthe other category we've defined. Interestingly, this other category is notnecessarily the smallest. In fact, given the number of insertion points for voiceover IP and the options available, it's probably the largest.Lucent, for example, has a line of products that allow the convergence of yourexisting voice with IP system at different points along the chain. Want to IP-enable your existing Definity PBX? PacketStar ITS-E is the option you need.Want IP-based trunking? You can use the Definity IP Trunk for Enterprise. Wantjust IP phones? You can buy Definity IP Ethernet Telephones. Want to leaveanalog phones and fax machines in place, but have an IP PBX? IPExchangeComm answers the call.VocalTec also provides piece parts such as the VocalTec Gatekeeper for IPaddress-to-phone number mapping. There's also VocalTec's InternetPhone, anaudio/video/PC phone and the VocalTec Telephony Gateway Series 120 and2000, two versions of IP public switched telephone network gateways.Additionally, Cisco, Nortel and 3Com have also outlined convergence strategieswith products that do everything from single device IP integration to completeinfrastructure replacement.

VOIP SERVICES



16/31

With a whole range of products being launched in this field, there are a variety ofservices being provided to the end user. The service basically involvestransferring voice from one end to the other. There are different ways though.

1 PC to Phone Services

These Services require a gateway on the receiving side to convert the IP packetsback to Telephone signals.

VocalTec Surf&Call

A good example would be the VocalTec Surf&Call. It enables Web toPhone Call center applications, promoting e-commerce. The web usersees an icon of Surf&Call and when he clicks on that he is connected tothe phone on the other side through the Internet via VocalTec gatewaybypassing the PSTN.

Dialpad.com

Dialpad.com has started an online VOIP service at www.dialpad.com. Thisoffers free of cost long distance calling service without any installation ofsoftware through the Internet. Its revenue comes from online advertising.

2 PC-to-PC services

These can be provided without a gateway on either side.

This service is obtained by a variety of software products such as

Microsoft NetMeeting VocalTec Iphone TaoTalk.com

It promotes video conferencing applications, Application share, White board etc.

3 Phone-to-Phone Services

A large number of Companies are providing long distance phone call services by

means of VOIP at reduced rates. Examples are:

AT&Ts 7cents per minute any day any time offer for long distance calls inthe United States. It also offers discounted international calls on purchaseof the above offer.

AOL offers 9cents/minute service.



17/31


18/31

Network Installation RequestDetermine Appropriate Internet Access Solution For Guest Usage

Requirements For Network

1. Deliver Always-On Internet Access At A High Speed2. Installation Must Provide Simple Interface For:a. Management Provisioningb. Guest Interaction & Usage

Installations Considered

CAT5 Installs Into Each Room For Use With Ethernet-Based Systemo Install Multiple CAT 5 Lines Throughout Building Without

Exceeding 100m Limito Bring All Cables to Central Patch Panel For Connection To LAN

Systemo Install Centralized Ethernet System (Switches, Routers, Etc.) &

Subscriber Management

Wireless Access Solution With Omni-Directional Transceiverso Install Multiple Access Points Inside Hotel

o Install CAT5 Links To Access Points

o Setup Sophisticated/Powerful WEP Security Policies

o Setup Effective Administration/Network Usage For Roamers

o Setup Policies To Disable Un-Authorized Nodes/Users Access

o Setup Subscriber Management System

Data-Over-POTS (Plain Old Telephone Service) Solutiono No New Wiring, Use Existing Pairs To Deliver Signal/Access

o Allows Long-Distance Runs (Up To 1000ft.1/333m)2 For Easy

Central MDFo Install Subscriber Management & Basic Services

(Routing/DHCP/DNS)o Install CPE Access Modules In Each Room

Cause For Service

In the increasingly competitive hospitality market, property/hotel managementcompanies are continually looking for creative ways to attract and retainguests/clients while at the same time increase the value of their properties withheightened service offerings. Property/hotel management companies regularlyoffer new services to improve the satisfaction that their guests experience duringtheir stay, including such amenities as fitness facilities, concierge services, mealdelivery options, and babysitting to name just a few. Today, that list is being



19/31

expanded to include advanced High Speed Internet Access services. Theconvenience of accessing an "always-on" Internet service at a high speed fromyour own hotel room is greatly influencing prospective guests and clients fromchoosing one hotel over another. Many business clients REQUIRE a high-speedInternet connection for access to their corporate VPN or for Internet based

research. The average guest finds convenience and entertainment in having afast on-line connection at their disposal. Business travelers often are indifferentto an additional charge for service or rates, as they are not paying for their stayanyway.

Using Data-Over-POTS

City-Net offers hardware solutions that assist property/hotel managementcompanies in improving guest satisfaction, staff utilization, asset performance,and vendor management, resulting in a seamless service delivery process frominitial customer contact through service fulfillment and supplier/vendor

management, thereby adding value to all participants in the process. Using aDOP (Data-Over-Pots) solution enables property managers to not only provide avalue added service, but to provide a profitable one as well! With expenses beingkept to a minimal, the system can be expanded to support hundreds of users,without substantial changes to the current infrastructure: translating to lessexpense, and more money in the property managers pocket.1 Field Testing Has Shown Connectivity And Flawless Transmission Up To2000ft. Your Results May Vary.2 City-Nets HPNA Solutions Have Been Tested & Certified To ProvideConnectivity Up To 1000ft. Other HPNA Devices Connectivity Distance MayVary.

Installation Site Overview

The property selected for this installation was located within close proximity to abusiness community in southern New Jersey. Also very close by wereconference facilities and business centers.Many nearby hotels began offering High-Speed access at low rates to competewith local copy shops and other notable hotspots. This particular hotel noticedthat a large amount of their clientele was frequenting the local copy shop toaccess the Internet and to perform basic document printing and copying. Thehotel also noticed an alarming amount of their clientele choosing to stay at the

surrounding properties that were offering Internet access. New clientele stoppedwalking through the door, and existing repeat guests were no longer makingreservations. It became very apparent to the Hotel Management that theyneeded to rectify this problem quickly, and effectively.The solution was clearer than ever: PROVIDE INTERNET ACCESS!Immediately the Hotel Management began submitting RFPs for dedicatedInternet access systems. The demand was simple: provide each room withaffordable high-speed access at a minimal installation and maintenance cost. If



20/31

possible, the hotel requested to have the ability to integrate an inexpensive yeteffective business center for their guests usage. The idea was to not onlycompete with surrounding hotels, but with business service shops as well. Thehotel management wanted a turnkey solution to provide their guests with aturnkey service, a one-stop shop for all of your business data and

printing/copying needs. The problem at hand was how to accomplish theseobjectives without going over budget, or causing complications in futureupgrades or after-installation maintenance. The hotel currently had an MITELdigital PBX system with 100 live extensions and 24 CO lines inbound. For theexisting equipment infrastructure, proposals were submitted to complement andbuild upon the existing architecture of the wiring, as well as some proposalsspecifying the deployment of new wiring.The core of the system that varied from proposal to proposal was thetransmission system. Getting the data signal to each room affordably and quicklywas the main variable from all the submissions. Few things differed from eachproposal; all contained a T1 line card for the PBX, as well as some routing and

switching equipment. What differed greatly were the types of switching androuting/services equipment selected, as well as the transmission mediums(Wireless, CAT5, CAT3, Fiber).

Proposed Switching/Medium

o Cisco Systems Ethernet Based System Using CAT 5/Fiber

o Cisco Systems Long Reach Ethernet Over POTS3

o Cisco Systems Aironet Solution Using 802.11B Wireless

o Bay Networks Ethernet Based System Using CAT 5o Tut Systems POTS Solution Using HPNA Type Technology4

o City-Net POTS Solution Using HPNA 1.1 Technology

The City-Net solution met all the desired results quite effectively.However, City-Net was able to deliver a price point more attractive than anyother system. Moreover, City-Net Technologys switches have a highercompatibility rate as well as heightened switching and system reliability. Anotherreason why City-Net was preferred over other switching solutions is the ability toscale your installation using management concentrators and stackingtechnology. City-Net switches offer convenient interfaces for the management

and control of up to 15 twelve-port switches from a single IP address.

Selected Solution

Data-Over-POTS Solution With City-Nets HPNA Technology



21/31

Installing a Data-Over-POTS solution is an excellent way to keep installationtimes to a minimum and material costs low. Data-Over-POTS enables you to adda Value Added Service to guests without interrupting their existing voice service.By utilizing the existing wiring within the facility, you can offer your users high-speed Internet access at a fraction of the cost of using an Ethernet-Based

delivery solution.City-Net Technology delivers not only a powerful and economic way to distributeaccess to the Internet, City-Net provides a foundation for a scalable, robustmanaged network for hundreds of subscribers. City-Net offers one of the onlyhardware platforms that enables full SNMP connectivity with a reliable andadministration free switching structure.Now that the switching and transmission mediums were decided, the rest of thesystem just fell into place. Using a relatively inexpensive subscriber managementsolution from a 3rd party, the hotel was able to provide the necessary basicnetwork services to their guests, with a few perks. The 3rd party solution enabledan IP PnP type connection system to ease the connection of new nodes or

guests computers onto the network without any configuration what so ever. Thistechnology enables anybody to plug in their PC to the hotel network, and gainaccess immediately without any type of configuration settings or alterations onthe user end. Although access is limited when first allowed access to thenetwork, once authenticated through Radius or an internal authenticationprocess the node connected to the appropriate room can surf the internet freely,and at blazingly fast speeds, all with little or no intervention on the hotel staffspart.The 3rd party solution also offered many avenues for revenue generation andfree services to be offered to and by the hotel. Matching these two platformstogether, the subscriber gateway (3rd party equipment) and City-Net switches,the hotel was able to create a powerful subscriber network, with almost noinstallation time and little configuration, and the best part is that it was all donewith no new wiring!

Installation layout and Description

1) CN 2000 Intelligent Central Management Switch Hub

CN-2000 Intelligent Central Management Switch Hub enables your network tohave the ultimate in flexibility and management. The CN-2000 unit offers up to 16Ethernet ports and 17 Console ports to expand your networking capacity by

interconnecting City-Net HomePNA switching units.One of the main features of the CN-2000 is the ability to manage other switcheswithin the CN family. The CN-2000 serves as a master central intelligencemanagement switch hub. It can manage up to 15 sets of City-Net HPNA switchessuch as the CN-1412. The slave switches should contain a DB-9 console port inits front panel to connect to the CN-2000. The CN-2000 Console port thenconnects to the slave switch via PS/2-DB-9 cable.Port-P can serve as an Up-link or a regular Ethernet port on CN-2000, when



22/31

the Uplink button is pressed down it serve as an Up-link port, when the Uplinkbutton is released it serve as a regular Ethernet port. Hence when connecting theCN-2000 to WAN via regular Cat. 5 cable on Port-P press down the Uplinkbutton.In order to provide management options and Internet access to slave units,

Console and Ethernet connections must be established from CN-2000 to theslave units using appropriate cables. Once the two units are connected, bothunits are ready to be access through Telnet for maintenances tools and ICDcommands or through Web interface for simple monitoring.

2) CN-1412 HPNA Switch

The CN-1412 HomePNA Switch has plenty of Ethernet ports, to offer you manypaths for upgrading your network, as well as 12 VLAN HomePNA ports ready toplug in to your existing wiring system using current CAT3/RJ-11 Installations.

Some highlights of the HomePNA Switch included: Supports security with port based VLAN function.

Supports Virtual LAN (VLAN) Grouping.

Auto Noise Leveling (Automatic & Manual).

Twelve 1Mbps HomePNA Ports

Four 10/100 Mbps Base-TX Ethernet Ports

One Console Port for HomePNA Switch.

Easy installation no new wire required inside the building.

Easy To Use Menu System and Command Interface.

HomePNA and Ethernet ports status Monitoring.

Frequency division multiplexing for uninterrupted simultaneous

voice/data transmission.

Supports Full and half duplex modes.

HomePNA port transmission speedup to 1Mbps

Supports 8K MAC addresses entries.3) HomePNA to Ethernet ConverterHomePNA to Ethernet Converter consists of one HomePNA port and twoEthernet port, and is a HomePNA to Ethernet converter. It does not require anysoftware, nor does it require opening the PCs case cover. You only need plug intwo cables (RJ-11 and RJ-45), and it is very easy to use. Enjoy uninterruptedvoice service (telephone) while surf the Internet with HomePNA.

Product Specifications:

Speed:1Mbps (phone line)

Ports:RJ-11, two connectors

Transmission Distance: Up to 500 ft (150 m)

LED Indicators: Link / Activity and Collision

Cabling: Standard Copper RJ-11



23/31

Communication Speed:10/100 Mbps

FREQUENTLY ASKED QUESTIONS (FAQ)

1) HOMEPNA

Q: What does HomePNA stand for?A: HomePNA Stands for Home Phone line Networking Alliance

Q: With HomePNA, Can I use my phone or fax and my Internetat the same time?A: Yes, you can use them at the same time.

Q: What are the primary objectives of HomePNA?A: The primary objectives of HomePNA are to:

" Ensure mass deployment of a consumer-friendly, low-cost, high-speed "no-new-wires" solution for in-home, MDU & MTU, phone line-based networking." Develop certification standards to ensure interoperability among HomePNAmember company products from the broadest possible range of technology andequipment vendors.

Q: What are the benefits of Do/POTS networking?A: The benefits of Do/POTS networking include: simultaneous, shared Internetaccess, printer/peripheral sharing, file and application sharing and networkedgaming. In addition, consumers can enjoy the use of each of these homeentertainment and information applications using existing wiring in the home.

2) SWITCH

Q: How many users can log into the switch through telnet at once?A: Telnet accepts only 1 connection at a time, however with the Http interfaceyou can have unlimited administrators logged in. The console port supports onlyone user per session.

Q: Can I turn off ports individually?A: Yes, Use the Console or Http Interface to do so.

Q: Can I adjust bandwidth per port?A: No, you cannot change the throughput thresholds.

Q: Do I have to set the speeds on the Ethernet ports?A: No, the ports are fully auto-negotiating for duplex and 10/100Mbps speed.

Q: Will the switch ever get too busy to handle large volumes of data?



24/31

A: No, with the flow control mechanisms and Back Pressure features in place,the unit will always be able to operate at maximum throughput.

Q: If I turn off my HomePNA Switch, will the settings be saved?A: YES, as long as you used the S save command in the ICD command

interface, all manual changes will be saved in the event that you turn off, or losepower to your switch.

Q: Can I use one port to support multiple users?A: Yes, the HomePNA standard supports up to 25 subscribers per port, forshared 1Mbps access on that port, however VLAN functionality is based per porton the switch itself. If multiple users are connected to the same port, then theywill be able to communicate with each other regardless of the VLAN setting onthe switch.

Q: I am using my HomePNA Switch for my office network; I cannot see the file-

sharing computer. Is there something wrong with my switch?A: Not at all, just set the VLAN function to OFF and all ports will be able tocommunicate with one another.

Q: Is the 1Mb of speed per port, or for the whole backplane?A: The ports are capable of 1Mb full duplex max throughput per port; thebackplane can handle vast amounts of traffic.

3) LAN

Q: Can I connect computers using HomePNA at distances longer than 1000ft?A: Under certain conditions it may be possible, our tests have proved 1000ft. asacceptable.

Q: How many pairs (cable pairs) does HomePNA transmission require?A: One pair.

Q: Which pair runs the data in a 2 pair RJ-11?A: It will run on either pair, just be sure that both ends of the cable have the samewiring configuration.

Q: Can I use Cat.5 Cable to make 4 RJ-11 connections?A: Yes.

Q: Will other types of HomePNA CPE (Customer Premises Equipment) work withthe HomePNA Switch?A: Yes, however all Manufacturers do not guarantee the performance of theirproducts when used with other manufacturer products.

4) WAN



25/31

Q: What types of WAN connections are compatible with the HomePNA Switch?A: Virtually any connection that has an Ethernet interface can be used.

Q: What router should I use for best results?

A: Any router should perform well with the HomePNA switch.

Q: My router has a firewall, how do I get through remotely to my switch tomonitor and change settings?A: In your firewall you should have a private connection-tunneling feature, toallow direct connections between addresses on your network and out of bandworkstations.

5) PBX

Q: Will the switch work with all PBXs?

A: Your Switch will work with all analog PBXs and most Digital systems, howevernot all PBX is compatible with this product, you may require a low pass filter,contact your vendor for availability.

Q: What PBX should I use for the best results?A: Any analog PBX should work well with our system. Because HomePNA isbased on FDM (Frequency Division Multiplexing) it sometimes conflicts withdigital PBX carrier signals

6) TROUBLESHOOTING

This section covers some common problem areas, also known fixes andsolutions. Although the solutions offered in this section should solve yourproblem, occasionally a problem might arise that takes on a symptom of anissue, hence cannot be solved in the same fashion.

A) Cross Talk Noise: Can Include Collisions and Link On/OffCross Talk Noise can be generated by HomePNA signals of bundled pairs oftelephone wire. When two pairs are adjacent to each other, or twisted aroundeach other they can create cross talk noise. A significant amount of cross talknoise can be generated on the HomePNA switch due to the high power output ofthe switch. Therefore, when telephone pairs are close together and twisted at theswitch, the adjacent port may suffer from above problem.Available solutions for this issue are:1. Use Cat.5 certified cables between the MDF and switches, including Cat.5punch down blocks and shielded/booted RJ-11 connectors going into theswitch.2. Turn on the Auto Noise Leveling Feature3. Make manual adjustments if previous solutions failed.



26/31

B) Reflection Noise: Caused by Un-Terminated Phone JacksHomePNA uses Frequency Division Multiplexing to allow simultaneous flow ofdata and voice services on same pair of wires. For this reason, your phone linesalso act as data transmission lines for the frequency range of 5.5 MHz to 9.5MHz. Therefore, if there is any open jack at the end of the circuit in HomePNA

port, the frequency information (data) will have nowhere to go, and reflect backinto the system, causing noise and non-function.Solution:Terminate those jacks using a Terminator or one of its specifications. Otherwise,remove the excess jacks from the circuit.

C) HomePNA Switch Causes Inoperable or Malfunctioning PBXThere are many models of PBX worldwide today. Some PBX does notcorrespond to certain standards when it comes to data transmission and FDM(Frequency Division Multiplexing). Occasionally, when a HomePNA switch isinstalled on a system with a PBX, the PBX will cease to operate or the

HomePNA switch stops functioning. The problem occurs due to the two devicesuse FDM toallow the sharing of the telephone wire. When one device is attached to theother, the impedance values begin to change the expected frequency responses,rendering both devices making one of them unusable.

Solution:Install an impedance matching filter to correct the frequency domain shift.Depending on the frequency domain, type of PBX, and amount of impedanceshift a filter may be needed between the PBX and the MDF or the CPE andTelephone set equipment.



27/31



28/31

Installation layout Diagram



29/31



30/31

Conclusion

This broad overview of the various issues involved in the transmission of voiceover an IP network give us an insight into the kinds of mechanisms that need tobe in place in the internet if we expect to provide services of voice transmission

over the internet.The differentiating characteristics of voice traffic that have been highlighted makeis necessary that we employ mechanisms in the internet that are able torecognize different type of traffic and are able to provide them different servicesbased on their different service requirements. On thing is clear, real-time voicetraffic does not map naturally onto the packet switched network. The differentmechanisms mentioned, to take into account the characteristics of real timevoice traffic are necessary to facilitate its service in the current best effort packetswitched network.

VOIP is growing fast. The very knowledge of the applications of this technology

is enough for users and manufacturers to flock towards it. It is ideal for computerbased communications and at the same time bringing down the cost ofmultimedia transfer. Hence VOIP products and services have flooded the market.The above paper presented the features of the products of a few major gameplayers in the field of VOIP.

REFERENCES

Technical Papers

"Voice Over IP" .http://www.techguide.com/Article on fundamentals of Voice over IP and issues related to quality of transfer

Readings on Voice Over IP: http://www.jeffseaman.com/reading05.html

Books B&N

Marcus Gonclaves, "Voice over IP Networks"

Uyless Black, "Voice over IP"

Jonathan Davidson, Jim Peters, "Voice Over IP Fundamentals,"

http://www.techguide.com/http://www.techguide.com/


31/31

IP over Voice

Documents