Analysis of Internet Protocol Telephony - Literature review Example

Tariq Al Hosani Course: Lecturer: Date: Learning Outcome (07) IP telephony IP telephony, synonymously referred to as Internet Telephony is the short form for Internet Protocol telephony (IPT) according to Furht (2008 371). IP telephony entails voice conversational routing via the internet using standard internet-protocol-based networks according to Ida (2009 144). Ida (2009 144) states that IP telephony is presently offered as an added service capability through broadband services especially the Asynchronous Digital Subscriber Line (ADSL). Peterson (2000 366) states that there are about five different types of IP telephony as follows: PC to PC, phone to phone, PC to phone, premises to network and premises to premises. The International Engineering Consortium (IEC: 2002 102 – 103) states that there are two major IP telephony standards. The first standard as argued by Hill Associates, Inc (2002 487) is the H.323 which is a specification by the Telecommunications Standardization Sector of the International Telecommunication Union-Telecommunications (ITU-T) sector. H.323 is the standardized international way of doing Voice over Internet Protocol (VoIP). The Internet Engineering Task Force (IETF), which is the second international standard of IP telephony, documented the Session Initiation Protocol (SIP) in RFC3261, 2002. SIP is the ideal standard for real-time multimedia signaling according to Furht (2008 371). A good example is the use of skype that makes available the use of the ability of IP telephony to subscribers in making and receiving telephone calls similarly as they would via the Public Switched Telephone Network (PSTN) at relatively low costs. Sub-Outcome 01 As earlier stated, there are two major organizations that are responsible for the development of IP Telephony or VoIP implementation. This section of the report takes an in-depth look into the significant contributions of the ITU-T and the IETF. The International Telecommunications Union-Telecommunications sector is an organization that runs under the auspices of the United Nations with its members being governments (Okon 22). The ITU-T came into being on 1st March 1993 as a replacement for the International Telegraph & Telephone Consultative Committee (CCITT) and has fifteen groups of organizations within it (Okon 22). The ITU-T is responsible for defining the H.323 specification, Packet-Based Multimedia Communications Systems. The H.323 incorporates the functionality of audio-visual and data conferencing (Hill Associations, Inc 487). The H.323 is an integration of many other standards, for example it is dependent on the H.225 protocol for call signaling similar to the Integrated Services Digital Network (ISDN). The H.245 protocol take responsibility in the control of media streams that flow between different terminals according to Camp (72). As argued by IEC (102), H.323 operates on the basis of Q.931 call control signaling. Since the 1980s, the Internet Engineering Task Force (IETF) has been busy working on the standardizing the Transmission Control Protocol/Internet Protocol (TCP/IP) as well as the Internet (IEC 230). The IETF is a global organization comprising of volunteers and works in groups of providers of telecommunications, vendors, internet providers, and governments as wells as college and university technology specialists (Camp 72). The IETF standard constitutes of a Media Gateway Control responsible for the development of architecture used in controlling gateways between Internet Protocol networks and a Telephone Number Mapping Group that works on protocols involved in the mapping of telephone numbers to other qualities like Uniform Resource Locators (URLs) used in contacting a resource that is associated with the numbers (National Research Council, US 231). IETF reacted to ITU-T’s H.323 recommendation and brought about the Session Initiation Protocol (SIP) with the belief that H.323 was not adequate to meet the requirements of the changing IP telephony in the sense that H.323’s structure of command was complex with extra-centralized and monolithic architecture as put by Sulkin (197). Sub-Outcome 02 Advantages Disadvantages Cost – compared to PSTN, IP Telephony costs much less as it depends on the already established internet operability. The setup cost of a Packet-switched network is also low compared to the cost of implementing a Plain Old Telephone System (POST). Subscribers also enjoy the use of bundles for unlimited calls according to Mohmand (19). There is need for high-speed internet connectivity that tends to be less available and affordable to all. In the absence of high-speed internet, Mohmand (20) argues that the quality of VoIP would be jeopardized. Low Tax Rates: Based on the fact that calls are transported via internet, VoIP is yet to be subject to heavy taxation by governments. In the US, for instance, VoIP is only subject to the 3% Federal Excise Tax unlike the Public Switched Telephone Network (Mohmand 19). Limitations of convergence: some providers of VoIP limit the ability of their services to being less compatible with other service providers as stated by Mohmand (21). More Features: Standard features included in the monthly fee are offered by many VoIP services providers. These services include free caller ID, call waiting ID, speed dialing and call forwarding amongst other free features (Mohmand 19). Lack of some common features: Some VoIP services do not connect to as directly to emergency calls like 911, provide for directory aids as well as sending of faxes as argued by Reynolds and Stair (162). Flexible Usage: Mohmand (20) states that VoIP allows for the usage of regular phones through a free adapter which allows for the usage of a subscriber’s phone anywhere in the world provided they have high-speed broadband access. Call quality: Low quality calls may result from delayed or lost data packets within the network system shared by users of VoIP (Reynolds and Stair 162). Sub-Outcome 03 The following illustrations portray VoIP’s configuration and how it operates: Fig. 1 below illustrates the laying down of hardware for a VoIP setup using ITU-T’s H.323 standard. Fig. 2 below illustrates the implementation and operation of VoIP using the IETF SIP system: Sub-Outcome 04 In this section, this report makes a comparison between ITU-T’s H.323 and IETF’s Session Initiation Protocol (SIP) VoIP protocols. In achieving this, the report puts into consideration the deployment, implementation and general operability of these two most popular standards of VoIP protocols. Despite being developed by two different and competing standard bodies, both H.323 and SIP implement a peer-to-peer relationship. However, SIP has an Intelligent User Agent for a client as opposed to H.323 that makes use of an intelligent H.323 terminal (Talukder, Ahmed and Yavagal 486). H.323 deployment is currently more widespread in comparison to SIP’s installations that are still garnering popularity according to Talukder et al (486). The core servers in ITU-T’s H.323 are the H.323 gatekeeper, gateway and multipoint control unit, compared to SIP proxy redirect, location and registration servers implemented in IETF’s SIP as argued by Talukder et al (486). When it comes to the exchange of capabilities, SIP employs the use of the Session Description Protocol (SDP) while H.323 makes use of numerous protocols like the H.225 protocol for call signaling similar to the Integrated Services Digital Network (ISDN) and the H.245 protocol that controls media streams that flow between different H.323 terminals (Camp 72). The type of encoding type used for control channels in SIP and H.323 is different. While SIP uses the text-based Universal Character Set Transformation Format 8 (UTF-8) encoding while H.323 uses the binary Abstract Syntax Notation 1 (ASN. 1) Packed Encoding Rules encoding. H.323 version 1 or 2 server processing has a state with version 3 and 4 being stateless while SIP’s server processing is either with state or stateless as presented by Talukder et al (486). Sub-Outcome 05 The following tables represent data extracts realized after conducting Quality of Service (QoS) tests over three VoIP service providers in the USA via whichvoip.com. For ease of interpreting the results, the following terminologies will need to be understood: Jitter refers to the translation of the delay difference in the arrival of data packets. High jitter levels cause dropping of packets and consequently interfere with the smooth playback. Delay is the total time a packet takes to arrive to its destination. Rarely is delay avoidable whenever data travels through networks. Packet loss is a percentage of the packets that failed to reach the intended destination over the total data packets that were sent. Mean Opinion Score (MOS) is the expression of approximated typical user rating calculated based on factors that impair packet transfer such as codec, delay, jitter, and packet loss. The highest level a VoIP service can attain is 5 and the poorest is 1. Usually, an MOS of between 4.0 and 5 reflects a very good QoS. Table 1: MOS results for Comcast Jitter me --> server 2.4 ms Jitter server --> me 3.7 ms Packet loss me --> server 0.0 % Packet loss server --> me 0.0 % Packet discards 0.0 % Packets out of order 0.0 % Estimated MOS score 4.0 Table 2 Speed Test Statistics Comcast Download speed 11506064 bps Upload speed 1911608 bps Download quality of service 75 % Upload quality of service 97 % Download test type socket Upload test type socket Maximum TCP delay 22 ms Average download pause 2 ms Minimum round trip time to server 26 ms Average round trip time to server 625 ms Estimated download bandwidth 14400000bps Route concurrency 1.251514 Download TCP forced idle 94 % Maximum route speed 20164608bps Table 3 MOS results for Vonage Jitter me --> server 3.0 ms Jitter server --> me 3.6 ms Packet loss me --> server 0.0 % Packet loss server --> me 0.0 % Packet discards 0.0 % Packets out of order 0.0 % Estimated MOS score 4.0 Table 4: Speed Test Statistics for Vonage Download speed 11506010 bps Upload speed 1911600 bps Download quality of service 74 % Upload quality of service 95 % Download test type socket Upload test type socket Maximum TCP delay 20 ms Average download pause 2 ms Minimum round trip time to server 25 ms Average round trip time to server 623 ms Estimated download bandwidth 14398900bps Route concurrency 1.23614 Download TCP forced idle 92% Maximum route speed 20164002bps Table 5: MOS results for AT&T Jitter me --> server 3.0 ms Jitter server --> me 3.6 ms Packet loss me --> server 0.0 % Packet loss server --> me 0.0 % Packet discards 0.0 % Packets out of order 0.0 % Estimated MOS score 4.0 Table 6: Speed Test Statistics for AT&T Download speed 11506064 bps Upload speed 1911608 bps Download quality of service 75 % Upload quality of service 97 % Download test type socket Upload test type socket Maximum TCP delay 22 ms Average download pause 2 ms Minimum round trip time to server 26 ms Average round trip time to server 625 ms Estimated download bandwidth 14400000bps Route concurrency 1.251514 Download TCP forced idle 94 % Maximum route speed 20164608bps Learning Outcome (06) Wireless Local Area Network (WLAN) is a synonym to Wireless Fidelity popularly known as Wi-Fi. WLAN evolved from the initially wired Local Area Network (LAN) where information travels via electromagnetic waves and hence eliminating the need for cabled connectivity since 1971 when the union between wireless and wired connections was established through the ALOHANET project in the University of Hawaii (Prabhu and Reddi 292). According to Behzad as cited by Xiu (1) a Wi-Fi can be assembled as a network on its own or coupled with a network that is wired. Terminologies Used in WLAN Gigahertz Gigahertz (abbreviated as GHz) is a unit that represents a billion clock cycles per second. In WLAN, GHz is measures the speed of the Central Processing Unit (CPU) and the radio frequencies (freewimaxinfo.com 2011). WiBro WiBro refers to Wireless Broadband and is developed by South Korea and adopted as a particular IEEE 802.16 standard subset in order to grant users the ability to access the internet via portable, handheld devices according to Wong, Kong and Liang (368). Hotspot Since WLAN is made available through a network cloud usually referred to as a Wi-Fi cloud, the places where the public has access to the Wi-Fi cloud is the hotspot (freewimaxinfo 2). Wi-Fi Finder Freewimaxinfo (2011) refers to Wi-Fi finder as a piece of hardware that is a small mouse-like device, which when turned on by the user conducts an automatic search for wireless network availability and switches on a LED light on successful network location, consequently prompting the user for connection. Access Point Although similar to Hotspot, Access points make use of the Wireless Access Protocol offering an interface for the wireless and wired devices as argued by freewimaxinfo (2011). Bandwidth Bandwidth is the range between the fastest and the slowest data transfer access and transfer rates that according to freewimaxinfo (2011) explains the information amount that can be broadcast through a network connection in megabits per second (Mbps). Packet Switching As described by freewimaxinfo (2011), packet switching refers to the technique involved in the sending of data packets via wireless networks from remote sites. The IEEE has defined Wi-Fi standards that entail modulation methods through the IEEE 802.11 standards with the most used and popular protocols being the 802.11b and 802.11g but includes 02.11c, 802.11f, 802.11h and the 802.11j. A practical example on the use of Wi-Fi is the availability of internet connectivity in cafés, airports and learning institutions where the public can access the internet from selected Hotspots within the geographical locales of the organization or institution. Sub-Outcome 01 The Institute of Electrical and Electronics Engineers (IEEE) 802.11 WLAN Standards The Wi-Fi standards defined by the IEEE 802.11 are classified according to channels on bands’ basis with each channel having varying specifications as well as frequency (freewimaxinfo 2). The IEEE 802.11 standards operate on data transmission frames that enable transmission stations to manage their channel(s) and exercise control over their wireless links on the network (freewimaxinfo 2). The IEEE 802.11 is a family of standards that come in three physical layers introduced in the 1997 but registered in the year 1999 whose transfer rate ranges between 1 and 2 Mbps as dictated by freewimaxinfo (2). The following section of the report discusses the different versions under the IEEE 802.11 standard. 802.11a According to Davis (281) is the improved 802.11 standards version since it makes use of the data link layer protocol with a similar frame with an operational bandwidth of 5GHz and a data range of 54 Mbps. 802.11b This standard came into being in the year 2000 making use of the 802.11 media but with an additional technology of modulation similar to that of 802.11 standards that requires 2.4 GHz to operate according to freewimaxinfo (2). Though relatively slow compared to the 802.11a, devices such as ovens, card less phones, visual display units and Bluetooth operate the 802.11b version (Davis 281). 802.11g Authorized in the year 2003, the IEEE 802.11g operates on the 2.4 GHz modulation with a physical layer data transfer rate of 54 Mbps (Davis 281). According to Davis (281), this is a later and speedy version with a backward compatibility to 802.11b. freewimaxinfo (2) supports that the 802.11g version through restricted use has the capability of forwarding error and improving codecs. 802.11n The IEEE 802.11n version seeks to deliver speedy transfer and operational rates of up to 100 Mbps with the capability of using both the 2.54 GHz bands and the 5 GHz spectrums (Davis 281). The recognition of the IEEE 802.11n as the final 802.11 endorsement came in the year 2009. This version is still receiving favored developments and improvements. Sub-Outcome 02 Table 1 below lists the advantages and disadvantages of WLANs as compared to LANs as presented by Singal (563 – 564). Advantages Disadvantages WLAN 1. There is quicker deployment since there is no need for physical connections for new users. 2. WLAN extends LAN connectivity to the internet to otherwise inaccessible locations. 3. The mobility and ease of WLAN access allows network access within the Wi-Fi cloud. 4. There is no installation or commission costs incurred since there is no need for physical connections and majority of WLAN devices are plug and play. 5. WLAN facilitates increased real-time productivity enhanced by the few requirements on setting up centralized databases. 1. There is a weakness due to limited bandwidth capability in supporting real time applications and video teleconferencing. 2. WLAN devices from varying manufacturers do sometimes suffer incompatibility mainly due to the absence of WLAN products’ interoperability. 3. Interference and external noise sometimes weaken the strength of signals transferred via wireless connectivity which sometimes result into huge errors or abrupt disconnections. 4. Due to the lack of a backbone, WLAN transmissions are less speedy, unreliable and less efficient. 5. The security of WLANs is susceptible to jamming and attacks that are malicious. LAN 1. LAN connectivity offers higher bandwidth as well as data transfer rates compared to WLAN. 2. The secure wired media on LAN translates into higher security that has lower susceptibility to security threats WLAN faces. 3. LAN connections are not interfered with by the presence of heavy material such as steel barriers within the connectivity locations. 4. There are low chances of interference and signal weakness in LAN compared to WLAN connections. 5. Most LAN devices tend to be compatible regardless of their varying manufacturers due to the tightened standardizations. 1. LAN is expensive to deploy compared to WLAN since there has to be physical connections involving cabling. 2. LAN inhibits mobility and access to wired network to inaccessible locations that WLAN would otherwise grant network access to. 3. Compared to WLAN, LAN makes it hard to gain network access due to the need for cabling as well as configuration. 4. LAN requires more networking expertise compared to WLAN as most devices in LAN have to be manually installed compared to WLAN plug and play devices. Sub-Outcome 03 Fig. 1 Fig. 1 above represents Sub-Outcome 04 Popular Security Measures That Limit Access to WLANs The report will now establish and discuss the implementation of WLAN security measures through the use of segmentation devices in the mitigation of exposure risks through the reduction of potential individual failure points, isolation and control of internal access of WLAN connectivity services. According to Valentine and Whitaker (176-177) the main ways used in applying security to WLANs are three. Authentication is the first method that requires provision of a usually secret code called a key in order to connect to an Access protocol and the Access Point should in turn prove its legitimacy to the client trying to accessing it, thereby establishing a mutual authentication procedure (Valentine and Whitaker 176). In implementing authentication, there is a dire need for strong cryptography allowing for the sending of the key without sending the key itself. The second common method is strong encryption which entails the application of a mathematical formula as well as a secret key to data, encrypting it into gibberish streams where only another device bearing the right key and the correct formula for decryption is capable of unscrambling ensuring that even successful encryption hackers would fail to decrypt (Valentine and Whitaker 177). Valentine and Whitaker (177) further offer that the third WLAN security measure is the implementation of Intrusion Detection/Intrusion Prevention. These are systems usually implemented as a Lightweight architecture part and are responsible for inhibiting restricted access (Valentine and Whitaker 177). A good example of Intrusion Detection/Intrusion Prevention WLAN security measure is a system capable of detecting new Access Points, cross-examining them and turning it off if categorized as rogue (Valentine and Whitaker 177). Sub-Outcome 05 The procedure below presents a detailed step-by-step theoretical approach that would be used in implementing security for an existing WLAN: 1. The first step will entail securing access to the wireless network in order to restrict unauthorized access: a) Alter the router’s Service Set Identifier (SSID) which happens to be the name of the LAN. b) The SSID broadcast will be disabled after altering the SSID to restrict access to configured devices only consequently eliminating the chances of unauthorized devices accessing the WLAN. c) Use specific Media Access Control (MAC) addresses in allowing access by Personal Computers and other devices. The MAC addresses may be entered manually or selected from a list of devices whose access is already authorized. 2. Securing clientele data through encryption a) The encryption process has three levels: Wired Equivalent Privacy (WEP), Wi-Fi Protected Access (WPA) and WPA2 according to Meyers and Haley (264). i. WEP ranks the lowest of the three data encryption levels but it is a good option in the absence of WPA and WPA2 support (Meyers and Haley 264). ii. WPA ranks higher than WEP but lower than WPA2 in terms of WLAN security implementation. iii. WPA2 is relatively a later entry into WLAN security although earlier routers can receive firmware upgrades that enable them to advantageously implement the highest level of data encryption (Meyers and Haley 264). WPA makes use of a Pre-Shared Key (PSK) method allowing composite passkeys in the form of letters, numerals and special characters in securing data. Works Cited Behzad, A. Wireless LAN radios: system definition to transistor design. Hoboken, NJ: John Wiley & Sons, Inc, 2008. Print. Camp, K. IP telephony demystified. New York, NY: Professional Publishing, 2002.. Print. Davis, H. Absolute beginner's guide to Wi-Fi wireless networking. USA: Que, 2009. Print. Furht, B. Encyclopedia of Multimedia (2nd Ed.). Spring Street, NY: Springer Science+Business Media, 2008. ISBN: 978-0-387-78415-1. Print. Hill Associates, Inc. Telecommunications: a beginner's guide. 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