Real time data transmission over a digital network is a fast and reliable means of transferring large amounts of data over long distances especially in multi-communication system. Non-real time data transmission is used to transmit data in the same way as real time but the transmission speed in this case is lower and the amount of data to be transmitted is limited.
Synchronous and asynchronous are methods used to transmit signals between the components of a computer and also between a computer and a network that is external to the computer in use. In synchronous transmission, the actions are measured against a time frame. Asynchronous transmissions are not measured in a time frame.
Unmanaged network devices are usually of a plug and play nature. This means that they have no configuration interface. Managed network devices on the other hand have at least a configuration interface to modify or vary its operations. The managed devices generally have more functionality than unmanaged devices.
The government provides the users and providers of digital networks with the legal framework that regulates the use of the networks to ensure quality of service while ensuring privacy over data being transmitted through the networks.
Service refers to the process of transmitting data from one point to another across a digital network. The digital network service provider is responsible for the transmission of the data on behalf of the client. The data transmission is done with help of varying technologies. However the most common technique is the integrated services digital network (ISDN). It allows for the transmission of data, voice and video at the same time through a telephone network.
The elements of a network design are as follows.
End devices: these refer to the data sources being transmitted within the network as well as to the specific destinations for this data. They are basically the data transmitters and receivers. Thus they act as the interface between the users and the network. These include devices such as computers.
Intermediary devices: These are the devices that connect the host devices to the network. Examples of such devices include switches.
Transmission medium: These are the equipment or medium that facilitates communication in the network by transporting the data. Examples of this include fiber optic cables.
Services: these refer to the software that enables the devices used in the network to use the resources of the network as required by the users.
Processor: this is the software that controls all the devices involved in communication within the network. It ensures effective and efficient communication by coordinating the functions of the various devices used in the network.
The image above shows a simple network which includes: –
- the server which provides the internet connection
- The workstation which is the computer that has been connected to the internet
- The switch or the router which provides a link between the server, printer and the workstation. This device is responsible for the connectivity to the internet
A direct route is an IP pocket transmission in which one computer can transmit the IP pocket to a second computer without relying on the support of a third computer within the network. In traffic routing this concept is referred to as direct routing. For example a computer in the USA can send the IP pocket to another in the UK without relaying on a network gateway. An indirect route is the situation whereby, a computer transmitting IP pocket to a second one has to relay on a network gateway to transmit the IP pocket. The network gateway is the third machine that links the transmitting and the receiving machines. This concept is referred to as indirect routing in traffic routing.
Network management consists of the following functions. First it involves monitoring the use of the network’s resources. Monitoring includes controlling the use of the resources to reduce the over head costs of using the network. Second, it involves planning the use of the resources to avoid wastage and enhance achievement of the network’s objectives. Third, monitoring ensures fair and rational allocation of the network’s resources among its users for effective service delivery. Monitoring also involves the process of ensuring the timely allocation, delivery and use of all required resources as well as the effective management of the use of these resources.
The second activity in network management is the allocation of frequencies. Appropriate allocation of frequencies is important to avoid overloading the network and interfering with the speed of data transmission. The frequency allocation criteria should depend on each user’s data transmission needs as well as the available network resources.
The third aspect of network management involves determining the system of traffic routing. The management should predetermine the preferred traffic routing system that is relevant to the needs of the network users. Consequently, the management should make it clear whether their preferred routing system will be direct or indirect depending on the needs of the users and the availability of resources.
Managing the configuration of the computers and the related devices used in the network is an important aspect of management. This will help in effective use of the machines. The last task in network management involves fault and security management. Fault management relates to the effective functioning of the machines and equipment used in the network. This includes repair and servicing of the network’s equipment. Security management on the other hand relates to the privacy over the data being transmitted in the network. This will involve formulation of privacy policies as well as developing mechanisms for controlling access to data being transmitted in the network.
There are four main routers used in a digital network which are as follows.
The first router is referred to as an edge router. It is usually located at the edge of the ISP network being used in the system. The function of this router is to transmit the EBGP of the transmitting network to the BGP speaker of the receiving network.
The second router is referred to as the subscriber router. This is usually positioned at the edge of the subscriber’s network. Thus it is usually owned by the users of the network rather than the service providers. Its function is to communicate the user’s EBGP to the service providers.
The third router is called inter-provider border router. It is specifically meant to interconnect ISPs. This means that it is responsible for maintaining BGP sessions between service providers.
The last router is referred to as the core router. This type of router is usually located within the autonomous system. The main function of this router is to facilitate transmission of data between edge routers.
2b types of firewall
Firewall refers to a security mechanism that is used to control illegal access to personal networks by external users. The concept is used both in the form of software that restricts access or hardware or a combination of both software and hardware. The examples are as follows.
Pocket filters: this type is responsible for verifying the pockets of data entering or leaving the network. The end user sets the criteria used to vet the pockets of data entering or leaving the network. Thus it uses the set criteria or rules to allow or reject the various pockets of data entering or leaving the network.
The second type of firewall is called application gateway. This one provides security over specific software and servers within the network. Its main demerit is that it can slow the operation of the network
The third type of firewall is referred to as circuit level gateway. In this case protection is ensured with the help of TCP and UDP connections. With the use of these connections farther verification of data pockets that enter or leave the network is not needed.
The last type of firewall is referred to as proxy server. The function of a proxy server is to verify the content of all pockets of data entering and leaving the network. It also conceals the IP address of the network.
Stateful pocket filter monitors all the pockets of data within the network. They have a dynamic system of verifying the pockets of data that enter or leave the network. The stateful pocket filters are considered to be intelligent for the fact that they verify the content of the pockets of data rather than just their headers.
There are various functions of core routers. In a direct route, the distribution machine sends a packet to a recipient machine without having to go through another medium, in this case referred to as a node. This course of action is referred to as direct routing. This happens when the machines are on the same network and usually do not require passing through a different route to convey the information.
Indirect routing happens when the machine that requires sending information to another network has to go past another machine. The mode that is used to get the middle machine is indirect routing. In this case, the other machine is in a different network. The middle machine usually acts as a gateway to the two computers.
Networks are usually autonomous of each other. This means that one network cannot use another to transmit data without proper authorization. The BGP is thus responsible for allowing other networks to use the provider’s network. This is done by assigning the specific routes that the external network will use to transmit data. This is the main purpose of BGP.
The figure on the diagram which has been indicated is a network diagram of a typical campus network which is multilayer. The figure shows a backbone connection which has the building s connections. The major layers on the diagram are the access layer, distribution layer and the core layer. Through the distribution and core layers, the access layer is able to efficiently network switching. The distribution layer makes use of the layer three methods as well as the core layer. The multilayer diagram as shown in the figure makes use of scalability. It can be able to incorporate new modes such as extra servers with changes in the design of the circuit. A new change or addition of an extra backbone has to go in line with two extra switches. The switches aid in the increase of the efficiency of the circuit including its redundancy.
The design of the circuit is in such a way that it can use the layer three services. The services include sharing the loads, segmenting as well as failure recovery. It is through Protocol Independent Multicasts that IP multicast data is effectively handled to produce results. The campus backbones are independent of the broadcasts.
Information can be forwarded using a basic setting of the router and also managing the information for the network. Congestion of the network has been found to greatly increase the network congestion in terms of traffic. At times multi routers are applied in such a way that they allow the end-users to use more than one connection and also in the forwarding of data between varieties of networks. This helps the network in alleviation of the bandwidth as it shares the load of the traffic on many lines.
On the other hand most of these kinds of routers make use of BGP which is quite complicated. The best way to surpass such a constraint is making use of some advanced technologies.
Round trip delay
Round trip delay can be defined as the duration taken by a signal for transmission within a closed circuit to completely take place. It is mostly applied in signals that interact in two ways during their transmission. Such a system is like telephony systems. In such a system, the round trip affects the rate of throughput of the whole system.
Transmission propagation delay
This is the total time that a signal head takes to be transmitted from the sending media to the receiving media. It is the ratio between the length of the link and the speed of propagation over that medium. It can be calculated as distance divided by time. Propagation delay is a big barrier between the connections in computers which transmit data over high speed.
Propagation delay ratio = distance/speed
Coaxial cable: 10km/1Mbps
Standard methods of accessing the internet
- Dial up: – this connection is where a user connects to the network through a server and through a 56K modem. This connection is provided by the ISPs and happens to be very slow. The identified connection is in such a way that the internet enabled machine dials up a specific number which is made available by the Internet Service Provider. Dialing up this number allows for the machine to connect to the modem of the particular server and in turn allows for internet connection through the modem. This connection is very slow and ranges from 36 to 40 Kbits/s
- Broadband internet connects the computer via a cable and usually has a speed of about 1Mbit/s
- Asymmetric Digital Subscriber lines connect to the internet through broadband. In this mode of connection a normal telephone line is subdivided between data and voice. In this kind of connection, it is possible to be connected both to the internet and also for voice use. The speeds for this connection vary with speed as below. 512kbit/s/128kbit/s, 1 Mbit/s/256kbit/s and 3 Mbit/s/768kbit/s in order of download followed by upload.
- Wi-Fi: – this is a wireless internet access. This connection needs the user to be in a hotspot for the pc to be able to access the internet. The hotspot can be confined to secluded areas like universities, a park or a city.
- Power line: – this allows access of the broadband. Most carrier signals for this access mode are 100 MHz and below. The major disadvantage with this access mode is due to signal interference of radio connections.
- Cell phones: – cell phones connect through the local network service providers.
Functional elements in network design
- Hosts: – these are the basic communication sources in the network. These devices connect the end user of a particular network to the network itself. Such devices can be computers, phones etc.
- Intermediary devices: – these are the devices that connect the host with other hosts. It is through these devices that the main elements making up the network are connected to each other for effective functioning of the system. The user cannot see these devices.
- Transmission media: – this is the physical connectivity of the network devices. Some of such media include cables like copper wires, fiber cables (optic fiber) or wireless connections like radio.
- Services: this is the software bit of the connection that offers the applications like the browsers. This software is responsible for the transfer of data and other resources to the end user.
- Processes: – this is the software that normally runs on the main network for the sake of the communication functionality. It also happens in communication protocols which can be viewed by the end users.
- Messages: – these are the normal messages that are communicated by the end users over the network.
The media and the devices in the network comprise of the main hardware and the services consist of the software part of the network.
Network management involves the process of planning, controlling, deploying, allocating, coordinating as well as monitoring the various resources that make up a network, the process of network planning, allocation of frequency, traffic routing with an aim of supporting load- balancing, authorizing the distribution of keys used in cryptography, managing the process of configuration, error, security, band width and performance management as well as accounting and route analytics management.
Data collection and data collection processes during network management is done using various means that include installed communications instruments, synthetic processes of monitoring that can be used as simulators of a number of identified connections, undertaken actions, real user as well as sniffers monitoring procedures. This process has changed from what it used to be in the early years whereby monitoring was the key aspect during network management. As a contrast, performance management is today considered to be a key factor in selecting the role of the Information Technology team. This has resulted into numerous challenges that have been mostly felt in international organizations.
Features of network routers
The network router has developed greatly in terms of the services it provides to more integrated systems. Apart from routing and connecting disparate networks, the device can be able to handle other properties too. The integration of the routing services has enabled the routers to deliver functions such as internet access, video, voice, data handling capabilities, wireless connections among a variety of other applications.
The integration of the routers has come up with so many benefits which include: the security of the routing operations and the flexibility in the recent IT developments. A good example is the functioning of the device in many applications. The built in technical; aspects like data, QoS and wireless connectivity is advantageous to many organizations as they tend to have a priority in the demands of their networks. Due to the built in nature of the services in the integrated router, a single device which is sophisticated can be installed by the relevant company instead of purchasing many diverse devices.
With the kind of routers, it is possible to have similar access to remote sites as well as the headquarters. With an integrated device the workers in the company can be able to access the network either from the company offices or from their places of residence. This data which can be accessed ranges from the applications for the on going businesses, video conferences and unified approaches to the business. The devices have solutions which can make it possible for the devices to be installed either in offices or at times even to upgrade in case of due expansions in the business premises.
It is possible to centralize the management of the premise. The integration of the network routers allows the relevant personnel to be able to access the network from a single centralized locality. In this case the personnel at the technical bench can be able to allocate some of the network resources to the prime projects while at the same time making sure that all the employees at their locations get all the required services.
There is integration of the network security. The network router has an approach towards the systems which gives permission to transfer the security requirements and also the dependability of the sole computers to the entire network. With such kinds of mechanisms, the company gets protected from virus attacks, codes which can be malicious amongst other probable intrusions that can be acquired by the end users without their consent. This has the end result by preventing the most valuable and vulnerable data from any kinds of attack that may arise from unwilling or willing sources. The multiple protections that can be given to the systems includes encrypting files, using firewalls, activating and using antivirus programs, and detecting and preventing intrusion.
Adding a switch to a router
It is possible to add a switch to a router particularly when one is using the router like a server (DHCP). To connect the switch to the router one should plug the port that is used for the uplink to the router. In this case one should a straight cable (cat5). One should avoid using a cross over as it tends not to be functional. When one is doing this, one of the computers in use should be plugged into the switch direct and the other computer plugged into the switch. The protocol of plugging the switch should be as indicated before. After the connection all the computers can now be connected to the internet. At this stage, both the computers can be able to connect to the internet otherwise the problem lies within the router or the switch.
The core router usually provides the computers with the ability to conduct data trafficking between the edge routers. This router has the capability to forward the data packets to different hosts within any given networks but cannot serve the same purpose on two differing networks. There is a big difference between this router and its edge counterpart. The edge router is used to route the data packets between a given network and other outer networks though within the backbone of that network.
Intrusion detection sensor
This is a software application that is put in a network for the purpose of monitoring the network for the likelihood of any intrusion into the system and consequently informing the right personnel of such an act. Prevention of intrusion is the process of attempting to bar the malicious sources from intruding into the system or the network. The systems usually identify the threats and keep a log of them and inform the administrators of the system later.
Their mode functioning include recording of the information about a particular field, notifying the responsible administration personnel and making a report on the happenings. As a way of response they can reconfigure the fire walls or change the security settings as they are located on the internet path.
Some of the common techniques that the systems employ use of are signature based detection and statistical anomaly detections. The latter mode of detection sets up a baseline of performance on the line of the network flow. It samples the traffic on the given network in trying to determine whether it is in the same baseline that it established. If the signal happens to be from an outside source, it establishes a trigger.
The former type of detection has a set of preset attacks which are referred to as signatures. A collection of them is kept and upon a match, an alert is set off.