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Lesson 9 Supporting business over the Web
Objective Key infrastructure technologies that support business

How Routers, TCP/IP, and Network Protocols support Business over the Web

Describe the key infrastructure technologies that support business over the Web.
The following technologies support business over the Web and have drastically changed how business is done.

Routers and TCP/IP

Most of the attributes such as transmission reliability and bandwidth control are being accomplished at the transport layer protocol level. Routers at the network layer are becoming addressable by the business application layer in terms of making rules that govern the transport.

Multicasting over IP Networks

IP multicast is a protocol for transmitting IP datagrams from one source to many destinations in a local or wide-area network of hosts that run the TCP/IP suite of protocols.

Multicast and ATM Networks

Audio and video conferencing applications are very bandwidth-intensive, and require extremely low latency from the underlying network multicast service. IP can be run over increasingly fast links to solve the bandwidth problem, but there still remains a serious latency problem with IP networks. Stated simply, because IP can support very large packets, it is possible for a small, time-critical packet to get "stuck" behind a large packet. Multicast over ATM networks can address this problem.
The transfer of multimedia information streams between any source and destination of can occur in a number of different ways.
  1. Simplex: Information flows in one direction only.
  2. Half-duplex: Information flows alternately in both directions.
  3. Full-duplex: Information flows in both directions simultaneously.
  4. Unicast: Information flows from the source to a single destination.
  5. Multicast: Information flows from the source to multiple destinations, comprising a subset of the nodes connected to the network.
  6. Broadcast: Information flows from the source to all destinations connected to the network.

  1. Datagrams: A piece of a message transmitted over a packet-switching network. One of the key features of a packet is that it contains the destination address in addition to the data.In IP networks, packets are often called datagrams.
  2. Latency: In general, the period of time that one component in a system is waiting for another component to do its part. This wastes time and reduces performance. Examples include the time lag between the beginning of a request for data and the moment it begins to be received, or the time necessary for a packet of data to travel across a network.
  3. ATM: Asynchronous Transfer Mode is network technology based on transferring data in cells or packets of a fixed size. The small, constant cell size allows ATM equipment to transmit video, audio, and computer data over the same network, and assure that no single type of data hogs the line.

Issues with Multicast and Unicast

Reliable transport:: The basic service provided by IP (multicast/unicast) is an unreliable datagram service.
This is appropriate for applications where concern with performance supercedes reliability. However, vendors providing IPC[1] tools develop the reliability layer that gives application guarantees of atomicity and reliability. For example, the Multicast Transport Protocol would be useful for developing applications such as distributed databases which need to be certain that all members of a multicast group agree on which packets have been received.


If you have information that should be transmitted to various (but usually not all) hosts over an internet, then Multicast is the answer. One common situation in which it is used is when distributing real time audio and video to the set of hosts which have joined a distributed conference. Multicast is much like radio or TV in the sense that only those who have tuned their receivers (by selecting a particular frequency they are interested in) receive the information. In other words, you hear the channel you are interested in, but not the others.

How the Netscape Browser helped shape Modern E-business

Marc Andreessen started working on the Mosaic web browser in 1992. He was a computer science student at the University of Illinois, but he spent a lot more time at the NCSA, the University's supercomputing center, than he did in the classroom. Working at (NCSA) National Center for Supercomputing Applications was fascinating, says Andreessen. The super-computing program in the mid-1980's originated because the government thought it was crucial that a powerful computing infrastructure be provided for scientists. An interesting thing happened around 1990: all the supercomputing centers essentially stopped running supercomputers. They shut down the Crays since they could no longer afford to keep them running, especially with the advent of more cost efficient microprocessors. Since it no longer made sense to run a supercomputer, what do you do? As a result, networking quickly became a very big part of NCSA. The theory being that the next stage would be to link together everything, especially scientists and educators who up until that point had been using the Crays. Networking had arrived so fast, and everything was happening so rapidly, that network engineers had not yet gotten around to making it accessible.

Network Protocols

Most high-level network protocols (such as the TCP[2] UDP[3] ) only provide a unicast transmission service. That is, nodes of the network only have the ability to send data to one other node at a time. A better way to transmit data from one source to many destinations is to provide a multicast transport service. With a multicast transport service, a single node can send data to many destinations by making just a single call on the transport service. The benefits of multicast are more than just logical: many underlying transmission media (such as Ethernet) provide support for multicast and broadcast at the hardware and media-access level. When a multicast service is implemented over such a network, there is a huge improvement in performance. If the hardware supports multicast, packet "A" that is destined for "n" recipients can be sent as just a single packet.

MBONE web page
MBone, or multicast backbone on the Internet, is an extension to the Internet to support IP multicasting (two-way transmission of data between multiple sites). The MBONE is a virtual network because it shares the same physical media ( wires, routers, and other equipment) as the Internet. The MBONE allows multicast packets to travel through routers that are set up to handle only unicast traffic. Software that utilizes the MBONE hides the multicast packets in traditional unicast packets so that unicast routers can handle the information. The scheme whereby multicast packets are moved by putting them in regular unicast packets is called tunneling[4] .
The difference between multicasting and the MBONE lies in the fact that multicasting is a network routing facility, a method of sending packets to more than one site at a time. The MBONE is a loose confederation of sites that currently implement IP multicasting. For more information on MBONE, take a look at the MBONE web page.
Tunneling works by encapsulating a network protocol within packets carried by the second network. For example, tunnels are now used to connect islands of networks over the physical Internet. This is known as the Virtual Private Network (VPN, see below), and allows virtual secure networks to be created without the need of hardware.

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Most of the application-network interaction takes place within the router/transport layer, but heterogeneous (disparate) networks present interesting architectural challenges. For example, ensuring the interoperability between networkprotocols is no simple task. When transactions need to occur between two businesses or networks, resolving messaging issues between protocols is a necessity. Examples of disparate networks that need to communicate include Ethernet, token ring, FDDI, ATM .
  1. Interoperability: The ability of software and hardware on different machines to communicate with each other.
  2. Protocols: Sets of rules that regulate the way data is transmitted between computers. Examples are PPP, TCP, IP, RIP, POP, SNMP, SMTP, SLIP, ARP, RARP, PAP.
  3. Ethernet: A popular type of local area network (LAN), which sends data through radio frequency signals carried by a coaxial cable. Each computer on the LAN checks to see if another computer is transmitting and waits its turn to transmit. If two computers accidentally transmit at the same time and their messages collide, they wait and send again in turn.
  4. Token ringA local area network (LAN) in which computers are configured in a ring. A message (token) is passed from desktop to desktop. The token is used to avoid conflicts in transmission. A computer can only transmit messages while it holds the token. Token ring was developed by IBM
  5. FDDI : Fiber Distributed Data Interface. An industry standard covering the transmission of data, as pulses of light, over fiber optic links. Fiber optics allow data to flow at very high speeds, for example 100Mbps.
  6. ATM: Asynchronous Transfer Mode is network technology based on transferring data in cells or packets of a fixed size. The small, constant cell size allows ATM equipment to transmit video, audio, and computer data over the same network, and assure that no single type of data hogs the line.

[1]IPC: Inter-process communication allows one process to exchange data with another process. The processes can be running on the same computer or on different computers connected through a network. An example is a socket.
[2] (TCP) Transfer Control Protocol: TCP is one of the main protocols in TCP/IP networks. Whereas the IP protocol deals only with packets, TCP enables two hosts to establish a connection and exchange streams of data. TCP guarantees delivery of data and also guarantees that packets will be delivered in the same order in which they were sent.
[3](UDP) User datagram protocol: UDP is a connectionless protocol that, like TCP, runs on top of IP networks. Unlike TCP/IP, UDP/IP provides very few error recovery services, offering instead a direct way to send and receive datagrams over an IP network. It us used primarily for broadcasting messages over a network.
[4]Tunneling: A technology that enables one network to send its data via another network's connections.