Voice over Internet Protocol, Security and Implementation - Literature review Example

VoIP (Voice over Internet Protocol) Design, Security & Implementation In a small organisation with respect to improvement in voice quality and reduction in cost This is a review of literature on VoIP design, security and implementation in a small organisation. This technology has evolved rapidly in the past few years, to the point where it can offer voice quality on a par with “land lines,” reduce costs of local and long-distance calls, and offer other features and benefits which exceed those offered by conventional telephone services. This paper reviews several of the recent articles about VoIP. These articles help to answer the questions: Is it an appropriate technology for a small enterprise? And is the technology now mature enough to be adopted with relatively few problems? Assessment of VoIP quality over Internet Backbones (Markopoulou 2002) This article covers a review of VoIP technology five years ago. At that time, the technology was in the midst of evaluation over internet backbones. There was a significant difference between ISP’s; with a decided advantage to those ISP’s which were closer to the “Internet backbone,” or the central internet trunk lines. While VoIP systems at that time had the software and performance to perform well on dedicated Internet lines, there was a concern that many ISP’s were not yet up to the task. There were several items which needed to be assessed as a VoIP system was contemplated. These included special voice handling on Internet lines, which was partly resolved by line conditioners; choice of the right ISP with excellent access to Internet backbones; and, most importantly, a playout buffer scheme which made a large difference in perceived quality. An Experimental Study of the Skype Peer-to-Peer VoIP System (Guha 2007) There are a number of VoIP schemes which have evolved over the past five years. Skype’s P2P, or Peer-to-Peer, system uses well-known technology first developed by Gnutella and other P2P music- and file-sharing protocols. This article reviews data gathered in a black-box manner on Skype, the best-known P2P telephony system, from September, 2005 to January, 2006. The quality of a P2P VoIP system depends, to a great degree, on how many people are online at any one time. One of the concerns that the authors had was that previous music-sharing P2P systems, such as KaZaA, had high variances in usage, depending on when users wanted to download music. Since users tended to do this at night, there was a dearth of P2P users during the day. These authors found that the Skype P2P ‘rhythms’ were significantly different, tending to be diurnal and on weekends. The article points out that Skype offers three services, which include VoIP, but also includes IM, or internet messaging, and file transfers. As one contemplates a VoIP system for a small enterprise, one should be cognizant that more and more data over telephone and internet lines is not voice, and that one uses multi-media capabilities within the context of one telephone call. The ability to share files, IM and show video may all be important characteristics in a new system. The authors measured Skype’s quality over time, and found that the quality of service appeared to remain relatively constant over time. The authors measured Skype in all regions of the world, but found the best performance on the European continent (including the UK). One can expect, therefore, that the quality of the VoIP system should remain high. Solutions to performance problems in VoIP over an 802.11 wireless LAN (Wang 2005) The options that a small enterprise has to connect to the Internet can pose problems to VoIP quality. Although a VoIP phone call takes relatively little bandwidth (the authors estimate 10kb/second), there is a substantial amount of overhead related to transmission and reception between a PC connected with (Veeraghavan 2001) to a wireless router and/or wireless modem. There is a broader concern, that there are other transmissions which can interfere with Wi-Fi 80211 signals. If there is other transmission-control protocol (TCP) traffic, there can be transmission and voice reception deterioration even if only half the capacity is being used. These problems are particularly important in the light of new phone technology, such as that offered by Apple and Nokia, which allow VoIP telephone calls to be made from cell phones, which can effortlessly switch from cell networks to VoIP, depending on access to Wi-Fi networks (Konolafe 2003). The authors do not mention what sort of 802.11 wireless technology that they used, although the fact that they had 11MB/second indicates that it was 80211.a and/or g technology. The current 80211.n standard, plus the new WLAN technologies, may pose fewer problems, as their transmission speeds are up to ten times as fast. The authors do not address the problem of interference frequencies. With more wireless landline use, one should be particularly careful about 900kH and 2.4gH frequencies, which could cause interference. If a small enterprise is contemplating using wireless handsets, they should consider 5.8gH frequencies, which are less likely to pose interference problems. Security Considerations for Voice over IP Systems (Kuhn 2005) VoIP has a very different architecture than copper wire technology. Although the legacy line systems could also be tapped, the new technology also has the potential to be tapped as well, despite the fact that VoIP sends voice in packets (Ganguly 2006). This report focuses on security considerations for an organisation’s VoIP network and server architecture, which is appropriate for a small enterprise in the UK. As seen in other articles, the authors point to the need for improved components, including call processors, gateways, routers, firewalls and protocols. The performance level for these components must perforce be better than that used in regular data transmission. Since VoIP occurs in ‘real time,’ some of the security techniques that are used for data transmission are not applicable to voice transmission. Although several technical solutions exist, there were not yet standards which had been broadly accepted by the industry (as of early 2005). VoIP, particularly wireless-access VoIP, has many configurable parameters, including IP and MAC (physical) addresses, router addresses and specific gateways, such as call managers (Perkins 1996). These parameters may be established dynamically, which means that every time a telephone or a user logs on, there can be an opportunity for an intruder to break into the system. Some of the more recent changes in Wi-Fi access, such as the IPv6 and WPA protocols, have made it more difficult for intruders to crack the system, but older systems which rely on IPv4 and WEP (or open) protocols will be with us for a number of years (Fathi 2005). Although standards had not yet been worked out as of the time of this paper’s publication, the authors felt that the SIP and H.323 protocols were receiving the most attention and investment. They evaluate both protocols, and find that they both provide sufficient VoIP security. The article is particularly helpful in giving step-by-step recommendations on system architecture which both meets the security needs of an enterprise while not degrading the VoIP performance to a degree that users will be unhappy with the quality of telephone calls (Cole 2001). Bibliography Cole, R and Rosenbluth, J. “Voice over IP performance monitoring.” ACM Comput Commun Rev, 2001: 9-24. Fathi, H, Prasad, R, Chakraborty, S. “ Mobility management for VoIP in 3G systems: evaluation of low-latency handoff schemes.” IEEE, 2005: 96-104. Ganguly, S, Navda, V, Kim, K, Kashyap, A, Niculescu, D, Ismailov, R, Hong, S and Das, SR. “Performance Optimizations for deploying VoIP Services in Mesh Networks.” IEE Journal on Selected Areas in Communication0s, 2006: 2147-2158. Guha, S, Daswani, N, Jain, R. An Experimental Study of the Skype Peer-to-Peer VoIP System. Paper, Bellevue, WA: IPTPS, 2007. Hillenbrand, M, Gotze, J and Muller, P. “Voice over IP - Considerations for a Next Generation Architecture.” 31st Euromicro Conference on Software Engineering and Advanced Applications. Frankfurt: EUROOMICRO, 2005. 386-395. Konolafe, R and Gardner, O. “Aggregation of VoIP streams in a 3G mobile network: A teletraffic perspective.” Proc. Eur. Pers. Mobile Commun. Conf., 2003: 454-549. Kuhn, DR, Walsh, TJ and Fries, S. Security Considerations for Voice Over IP Systems. White Paper, Washington: NIST, Technology Administration, US Dept of Commerce, 2005. Markopoulou, AP, Tobagi, FA and Karem, MJ. Assessment of VoIP quality over Internet backbones. Paper, STanford, Stanford: Infocom 2002, 2002. Perkins, I. “IP Mobility Support.” RFC 2002, 1996: n.p. Veeraghavan, M, Cocker, N and Moors, T. “Support of Voice Services in IEEE 802.11 wireless LANs.” INFOCOM, 2001: 488-497. Wang, W, Liew, SC, Li, VOK. “Solutions to performance problems in VoIP over a 802.11 wireless LAN.” IEEE Transactions on Vehicular Technology 54, no. 1 (January 2005): 366-384. Read More