Convergence Essay Example For Students

Convergence Essay TABLE OF CONTENTSExecutive Summary 1Introduction 2Part I Business Factors 3What is Convergence? 3Toll Bypass 3Utilization ? Getting Your Moneys Worth 3Part II Technical Overview 4Mixed-Media Requirements 4Problems: Delay 4 Packet Loss 5 Jitter 5 Network Technology 5Voice over ATM 5Voice over Frame Relay 6Voice over IP 7Inter-Vendor Support 8H.323 8Part III Implementations 10Types of VoIP ImplementationsVoIP through a router 10 LAN Telephones 10IP PBX 11VoIP Gateway 12Conclusion 13Appendix A ? Works Cited 14IllustrationsChart 1 ? Cost of International Voice Calls 3Graph 1 ? Long 1-Way Voice Transmission 4Chart 2 ? Summary of H.32x Standards 8Picture 1 ? Converged Network Architecture 9Picture 2 ? H.323 Architecture 9Picture 3 ? VoIP through a Router 10Picture 4 ? LAN Telephones 11Picture 5 ? IP PBX 11Picture 6 ? VoIP Gateway 12Picture 7 ? Ciscos Consolidated Data-Voice Network 13EXECUTIVE SUMMARYThe universal belief, today, is that IP will become the transport for virtually all commu nications traffic. Yet, there are still fundamental issues involved with converging voice and data traffic onto the same medium. Many vendors and standards organizations are working on developing solutions that interoperate together. It is no longer desirable to have proprietary products that do not work outside the company walls. Users expect a quality of service equal to that which they are already experiencing. By making use of intelligent network design, advanced routing protocols and open-industry architecture this dream can become a reality. Umbrella standards, such as H.323, spell out a model that is non-vendor specific for providing voice, video and integrated data. Merging telephony and data will have two major benefits. The first, and most important to any businessperson, is the impact on the IT budget. Within the IT budget three areas will have savings: IT personnel, network equipment, transmission services. The IT personnel will have to be knowledgeable in both data and voice networking. Thus reducing the need for separate teams. In most cases the need for forklift upgrades has been eliminated. By simply adding hardware components and software the migration can begin. The second, and more significant than the first, is the new applications that this makes possible. Combining voice and data onto one packet infrastructure enables new capabilities that are not possible with separate networks. Together they produce a synergistic effect that can give a company customer interaction capabilities like never seen before. The network itself can be chosen for facilitating voice and data. The most impressive of which is voice over ATM. ATMs high speed, high availability, scalable architecture molds well to the requirements of convergence. Voice over IP is a more general technology allowing a variety of networks to run underneath its mature, sophisticated protocols. Several implementations allow for a gradual migration that many times uses much of the existing hardware. By properly planning and slowing making the migration, a company can be assured that end result will be a success. INTRODUCTIONConverging voice and data communications onto the same network is, by no means, easy. The two, although at first seeming alike, they are actually quite different at heart. Networks can be classified in one of two ways. The network is said to be connection oriented when a direct connection, physical or logical, is setup before data is transferred. Connection-less, however, simply addresses information and sends it to the recipient. Every packet is addressed and must be routed through the internetwork, meaning packets can take several different paths to the source. Voice networks are circuit-switching networks. They are connection oriented, whereby the caller and the called party have a connection established before talking. Data networks are a packet switc hing technology. No setup occurs when data is sent and received. Each individual packet must receive a network layer header with the destination address. When the packet is passed between routers, not all packets take the same path. This is because routing protocols have intelligent route selection capabilities that allow load balancing and other features. It is easy to see intrinsic difference. How do you make connection-less behave as connection oriented?Voice service has been highly refined for many years. Users have become accustomed to highly available, clear, fast connections when making phone calls. This presents a major quality of service (QoS) hurtle that must be overcome for Voice over IP to be accepted Protocols have been developed that use certain bits within the IP header to define the Type of Service (ToS). Currently, many vendors have used these bits in a proprietary manor but the IETF has decided to redefine them. Another issue arises when defining QoS, what do you d o differently with high priority traffic versus low? To this RSVP has answered with the ability to define a route through the network and then have high priority (Voice) traffic routed along that same path. The leaps and bounds that technology has made in recent years have opened the door to faster routers with much more sophisticated routing protocols. Enabling higher and higher data rates that are necessary for the limited delay requirements of voice traffic. Even network design has been rethought to allow for speeder and more reliable connections. Innovations and education from vendors like Cisco, 3COM and Nortel have lead to lowered congestion on network segments. This enables networks to scale as large as the company and maintain similar features across the whole enterprise. Throughout this paper it will discuss both business and technical issues associated with migrating towards a seamless voice and data network. It would be unwise to try to implement these changes too quickly. The quality of service users are accustomed to must not change. The object of networking is to increase productivity and decrease cost. A converged network promises both but the migration process must be well managed in order to ensure a smooth transition. Business FactorsWhat is Convergence? Convergence has been a hot topic for many years. The dream spawned by the Internets wealth of possibilities, of a combined voice, video and data network has fueled vendors to come up with an industry-wide, non-vendor-specific solutions. More importantly for business this dream spells big savings over the long run. Three areas of the IT budget should see savings. ? IT Personnel ? Rather than having data-network personnel and voice-network personnel. IT staff will be required to be knowledgeab le in both areas and therefore cutback to one slightly larger team. ? Network Equipment ? Although at first, in order to establish the technology, cost may be significant. By using Computer Telephony Integration (CTI) the need for dedicated, specialized devices can be reduced. Also packet switching is soon becoming as much as 20 ? 50 times more cost-effective than circuit switching because of its connection-less nature. ? Transmission Services ? Mainly dealing with cost savings from non-US calls. Convergence is defined as combining voice and data in one media without channellizing. There are basically five ways of doing this:? Point to Point digital circuits? LAN? Frame Relay? Corporate intranet? InternetToll BypassThe global market that we live in today demands that businesses conduct calls with foreign countries. The price of these calls can have a high impact on the IT budget (see chart 1). Destination Country Cost Per MinuteIreland US$0.40Japan US$0.35Israel US$0.75Brazil US$0.55For most large companies, US calls should not cost more than three cents a minute. The cost savings for international calls, on the other hand, by using VoIP is obvious after considering the volume of calls that occur. -Packet Magazine V.12, N.2, page 63Utilization ? Getting your Moneys WorthIts a fact that data communications is bursty. Meaning, data transfer peaks for a moment and then is stagnant. Consider when you are browsing on the Internet. Data transfer is high as the page downloads. Once loaded, you sit and read. The connection is idle and bandwidth is not being used. For a business, this unused bandwidth is wasteful because it could be used for other traffic that may need it. Utilization is formally defined as ?The percent of total available capacity in use.? Capacity being the total ?data carrying capability of a circuit or network in bits per second.? The cost associated with high-speed circuits is too great to allow them to go unused. Optimum network utilization occurs for Ethernet under 37%. After this point the network is too saturated with communications and token passing methods out perform CSMA/CD (Carrier Sensed Multiple Access with Collision Detection). For token passing methods utilization can approach upwards of 70%. WAN links, such as those used for VoIP, should be operating at about 70% utilization before considering an upgrade. Who Has Seen the Wind: Meaning of Life EssayWhen the remote router receives the Q.931 call request, it signals a line seizure to the PBX. After the PBX acknowledges, the router forwards the dialed digits to the PBX and signals a call acknowledgment to the originating router. All the responsibility for session establishment and signaling is with the end stations. To successfully accomplish this, additional enhancements must be made to the signaling stack. H.323 is such an addition and will be discussed in-depth next. Corporations should already have an IP addressing scheme in place. The voice interfaces will show up as additional nodes, either as an extension of the existing scheme or with new IP addresses. The dial plan mapper performs translation of these addresses. The destination telephone number or some portion is mapped to the destination IP address. When the number is received from the PBX, the router compares the number to those mapped in the routing table. If a match is found, the call is routed to the IP host and is transparent to the user. VoIP real strength is rooted in IPs mature and sophisticated routing protocols. By using routing protocols such as Enhanced Interior Gateway Routing Protocol (EIGRP) specific factors including delay are taken into consideration for best route decisions. Other advanced features like policy routing and access-list allow you to create highly secure networks. Increasing innovations, such as tag switching, are also being developed to allow better traffic engineering. This will lead to the ability to shift traffic load based on different variables, such as time of day. Traditionally, IP traffic has been handled on a ?best effort? mechanism. Traffic was first come, first serve but voice is not tolerant to retransmission and delay. Also the variable packet size problem is an issue. Once again using RSVP to initially find a route through network and then using RFC 1717 to break up the large packet to a standard, smaller size was the solution. Weighed fair queuing was also used to put different traffic types into specific QoS queues and thus reducing queuing delay. H.323The ITU created the H.323 standard to enable mixed-media communications over packet based networks that do not provide QoS. The standard is said to be an umbrella encompassing various associated standards (See chart 2). Although H.323 provides support for audio, video, data and multipoint conferencing, only the audio support is mandatory. H.320 H.321 H.322 H.323 H.324Purpose Narrowband ISDN Broadband ISDN, LAN, ATM Guaranteed bandwidth packet networks No guaranteed bandwidth packet networks and Ethernet Analog PSTN telephone systemAudio G.711, 722, 728 G.711, 722, 728 G.711, 722, 728 G.711, 722, 723, 728, 729 G.723Video H.261, 263 H.261, 263 H.261, 263 H.261, 263 H.261, 263Multipoint H.231, 243 H.231, 243 H.242, 243 H.323 Control H.320, 242 H.242 H.231, 243 H.245 H.245Interface I.400 AAL I.400, TCP/IP UDP/IP, TCP/IP V.34-The Irwin Handbook of Telecommunications, 4th edition. H.323 power comes from its multitude of other standards. Many applications are possible by using this architecture including: Internet telephony, desktop videoconferencing, LAN telephony, conference calling and mixed media conferences such as voice, video and whiteboard. Interoperability is a key feature in todays networks. H.323 uses industry open standards which when followed by vendors allows other products to work together. A general H.323 architecture is shown in figures 1 2 below. The TCP/IP network uses TCP (reliable connection-oriented protocol) for call setup and UDP (fast, connection-less protocol) for voice packets. A signaling channel known as the RAS channel is used for communications between devices. Real-Time Transport (RTP) is used to sequence packets, compensating for UDPs lack of this capability. Real-Time Control Protocol (RTCP) monitors QoS. -Figure 1-Radcom VoIP Technology Protocol Reference poster. ? Gatekeeper ? Manages a zone (collection of H.323 devices). o Required Functionality ? Address translation, admissions and bandwidth control. o Optional Functionality ? Call authorization, bandwidth management, supplementary services, directory services, call management services. ? Gateway ? Provides interoperability between different networks, converts signaling and media e.g. IP/PSTN gateway? H.323 Terminal ? Endpoint on a LAN. Supports real-time, 2-way communications with another H.323 entity. Must support voice (audio codecs) and signaling (Q.931, H.245, RAS). Optionally supports video and data e.g. PC phone or videophone, Ethernet phone. ? MCU ? Supports conferences between 3 or more endpoints. Contains multipoint controller (MC) for signaling. May contain multi-point processors (MP) for media stream processing. Can be stand-alone (i.e. PC) or integrated into a gateway, gatekeeper or terminal. ImplementationsTypes of VoIP ImplementationsVoIP through a RouterBenefits:? If a PBX already exists, it makes maximum use of existing resources? The service is completely transparent to users? The connection can be completed over any available packet network. ? Blockage of voice calls should be rare since the PBX can complete the call over the PSTN. LAN TELEPHONESThis configuration allows you to connect devices directly to the network. Analog telephones can be connected using an Ethernet adapter through a PC. The PC gives you a lot of versatility because it can substitute for the telephones button interface. Calls within the zone are controlled by the VoIP gateway rather than having a PBX onsite. This implementation is inexpensive and great for branch offices. IP PBXAlso known as the un-PBX. This implementation has PBX hardware and software function loaded on a PC running something like Windows NT or Unix. The various cards can be loaded into the PC and generate call-processing programs. Obviously, though, the fault-tolerance of an un-PBX compared to a real PBX is no contest. PBXs are very specialized and refined systems that are far more robust than any PC. VoIP through a GatewayThis implementation is very similar to VoIP through a router, however, instead of using a router to route the calls; the functionality is part of the PBX. This can be a function of one of the cards in the PBX or simply a stand-alone device connected to the PBX. According to the Irwin Handbook of Telecommunications, ?Some manufacturers such as Lucent and Nortel provide IP trunk cards, but others do not, in which case the PBX would connect to either the router or the gateway through standard T1/E1 or analog tie trunk cards. Technology Essays