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2008 Technology - Internet - Volume 3 - IP Techniqueshttp://www.chinaccm.com/4S/4S16/4S1603/news/20081208/165942.asp Report Summary This handbook is intended to support technical and management people in understanding the major IP technologies used in VoIP networks, video multicast systems and many other aspects of Internet service delivery and backbone operations. We begin by discussing the IPv4 addressing system, the looming exhaustion of fresh IPv4 address space and the methods routers use to classify each packet in order to decide which peer router to forward it to. We discuss the two link-state internal routing protocols: Intermediate-System to Intermediate-System (IS-IS) and Open Shortest Path First (OSPF). We explain the operation of the path-vector Border Gateway (News - Alert) Protocol (BGP) routing system which links all ISP and end-user networks to form the Internet. We discuss the workload of transit routers and multihomed border routers, both of which are described as being in the 'Default Free Zone'. The communications, computing and data storage burdens of these routers is the primary reason for the need for a new routing and addressing architecture for the Internet. Network Address Translation (NAT) firewalls are commonly used in corporate and home networks, such as to allow a single-IP address DSL service to be used by multiple computers. We discuss NAT operation and several Internet Engineering Task Force (IETF) standards which are intended to help application developers traverse the barriers imposed by NAT. NAT adoption is increasingly ubiquitous due to the IPv4 address shortage and this causes major difficulties for the reliable implementation of peer-to-peer and real-time applications, including VoIP, presence and instant messaging systems. We discuss IPsec security which provides authentication and encryption within the TCP/IP protocol suite itself, the operation of the Internet Key Exchange (IKE) Protocol and the use of hash functions with digital signatures for authentication. Multiprotocol Label Switching (MPLS) is an important IETF protocol by which traffic can be transported across large networks with full Quality of Service (QoS) guarantees and minimal forwarding effort by routers. We explain MPLS in detail, together with the Resource Reservation Protocol-Traffic Engineering (RSVP-TE) approach to establishing the label-switched paths. We also discuss MPLS Fast Rerouting and Pseudo-Wires and how QoS is implemented with MPLS using IntServ and DiffServ. We discuss Next Generation Networks (News - Alert) (NGNs)¨Ca term which standards bodies and companies use in rather different ways. We discuss Cisco's NGN architecture and its support of IPVT multicasting and contrast this with some yet to be implemented NGN proposals by standards bodies, including ETSI (News - Alert)-TISPAN, the ITU and ECMA. We discuss VoIP in a variety of settings, including residential and SOHO, carrier backbone, wireless and mobile, for in-office replacement of Private Automatic Branch Exchange (PABX) systems and Centrex. The numbering and addressing arrangements for VoIP are more diverse and complex than those of the Public Switched Telephone Network (PSTN). We discuss the conventional E.164 numbering scheme, SIP addressing, ENUM mapping of E.164 addresses to the Internet Domain Name System, and some lightweight alternatives to the official, slowly deployed, ENUM system. We describe the Real Time Protocol (RTP), H.323, Session Initiation Protocol (News - Alert) (SIP) and the Session Description Protocol (SDP) and the various network elements which constitute a complete VoIP system. We also discuss other major voice protocols, including Skype, the Asterisk (News - Alert) inter-exchange protocol IAX2, XMPP, Jabber and Jingle. This handbook aims to convey a working understanding of many of the techniques which are vital to understanding and planning Internet services, especially those based on VoIP and other real-time forms of communication. Search more reports,click: http://search.chinaccm.com/ As a community-building service, TMCnet allows user submitted content which is not always proofed by TMCnet editors. If you feel this entry is of inferior quality or wish to report it for some reason, please forward the URL to "webedit [AT] tmcnet [DOT] com" with your comments. |