Managers and technical specialists face an increasing challenge keeping abreast of the underlying technologies of today's IP networks.

The most significant techniques behind the Internet and private TCP/IP networks are explained in a new BuddeComm biennial report in Handbook format: 2008 Technology - Internet - Volume 3 - IP Techniques. The BuddeComm Handbooks provide an overview and functional understanding of important technologies which are otherwise hard to grasp without one-on-one training or lengthy study of voluminous engineering-oriented material.

The IP Techniques Handbook begins with a discussion of the IPv4 (Internet Protocol version 4) 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.

The Handbook describes the three techniques routers use to decide the best path on which to forward packets. One of two routing protocols - IS-IS (Intermediate-System to Intermediate-System) and OSPF (Open Shortest Path First) - are used inside ISP and end-user networks. Routers handling the links between these networks - forming the global Internet - all use the path-vector Border Gateway Protocol (BGP) routing system.

The routers with the greatest BGP workload are the transit routers and multihomed border routers, both of which are described as being in the Internet’s ‘Default-Free Zone’ DFZ. The communications, computing and data storage requirements of these routers places serious cost burdens on all ISPs and many large end-user networks, such as those of universities and corporations.

The Internet’s current architecture is ill-suited to the accelerating growth in the number of networks each of these DFZ routers must develop optimal paths to, prompting the IETF and IRTF (Internet Engineering and Research Task Forces) to work towards a new routing and addressing architecture for the Internet.

Efforts to reduce the load on these DFZ routers leads to sub-optimal usage of IPv4 address space. With a maximum possible 3.7 billion addresses available, today’s IPv4 Internet will run out of fresh supplies of unused address blocks around 2010. This will prompt greater efforts to use this limited space more intensively - with more, finer, divisions and consequently still greater burdens on the DFZ routers.

One technique which enables many client computers - such as desktop machines, rather than servers – to use a single IPv4 address is Network Address Translation (NAT). NAT firewalls are commonly used in corporate and home networks and provide some measure of security against attacks from the Internet. However widespread adoption of NAT has destroyed the end-to-end principle on which the Internet was founded: any computer being able to directly address and communicate with any other computer.

The Handbook contains detailed discussion of NAT operation and several 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.

The Handbook provides an overview of 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 (Internet Engineering Task Force) protocol by which traffic can be transported across large networks with full Quality of Service (QoS) guarantees and minimal forwarding effort by routers. QoS is used in private networks to ensure a stream of packets for a communication such as VoIP or video are delivered with the required reliability and within the necessary timing constrains.

The Handbook explains MPLS in detail, together with the RSVP-TE (Resource Reservation Protocol - Traffic Engineering) approach to establishing the label-switched paths, MPLS Fast Rerouting, Pseudo-Wires and the IntServ and DiffServ techniques of providing QoS with MPLS.

‘Next Generation Networks’ (NGNs) – a term which standards bodies and companies use in rather different ways. The handbook includes discussion of 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-TISPAN, the ITU and ECMA.

VoIP (Voice over Internet Protocol) is now widely adopted in a variety of settings, including residential and SoHo, carrier backbone, wireless and mobile, for in-office replacement of PABX (Private Automatic Branch Exchange) systems and Centrex. The handbook discusses the numbering and addressing arrangements for VoIP, which are more diverse and complex than those of the PSTN (Public Switched Telephone Network). The conventional phone system uses the E.164 numbering scheme, and while VoIP system can use this, they can also use 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.

The handbook describes the Real Time Protocol (RTP), H.323, Session Initiation Protocol (SIP) and the Session Description Protocol (SDP) and the various network elements which constitute a complete VoIP system. Other major voice protocols, including Skype, the Asterisk inter-exchange protocol IAX2, XMPP, Jabber and Jingle are also discussed.