Hey Guys.. wellcome to my Essays Hub, feel free to read the Essays relating to title (LAN AND WAN DESIGNING).
1.0 LAN switching technology:
LAN Switching technology is a kind of packet switching which is used in Local Area Networks. A switching technology is an important for a network design. These technologies allow traffic that is to be sent only where it is needed using fast and hardware based methods. In the given design the sites are to be divided in to subnets so that the users out of the company's network cannot gain access to the server of the company. The unnecessary traffic that is generated in the site as the frames broadcast is forwarded to every computer on the site is not accepted by the host server. To overcome this problem we can use the VLANs switching technology for both the sites as decisions are very easily made by the VLAN switches. The data sharing between the sites is easily possible by using the VLAN routing at the distribution layer. By using this technology the departments of the sites can transfer the data within the site securely and easily (S. Matsui, 2006). The VLAN switching allows the user to access the relevant server of the department keeping the security measures in concern. VLAN is the creation of partitions of the LAN network into subnets and each subnet is assigned a VLAN ID. These partitions can be on a single router or different routers and even can be on a network or on a VPN. The VLAN Ids are then used for enabling the switching and routing engines to make the right decisions that are defined in the VLAN configuration.
2.0 Virtual Private Networks:
Our structure with one headquarters and four remote sites can take four lines each form the head quarters to four diverse sites. Frame relay would be the mostly price effective method out as remote sites needs often to access internet it force further price effective to mend each allotment to internet and through internet as WAN convey or facts be able to be send in excess of data between sites. Contrast to draw relay and lease lines internet is by not secured as of the hackers attacks (LAN Design and security, Syed Khundmir, University of Sunderland, 2009).
By means of the close to Private Networks these safety issues can be solve over internet as WAN services. The adding of private intranet regarding the public networks or internet is VPN ensure cost efficient and secluded links for end to end presentation. With the help of rational tunnels personal intranet is extended in the manner of end to end presentation enabling point to point message as shown in the figure below (M. Gupta, 2003):
Figure: Typical setup of VPN (M. Gupta, 2003)
2.1 Verification:
The process of data transmitted to the required end is with security is known as Authentication. It also means the consistency of the data wherewithal to the receiver. At most it wants a user ID and password to permit and access the resources (A. Wai, 2003).
2.2 Encryption:
The standard data altered in the manner of unreadable is known as Encryption. By specify the key this process is ended as these keys are aged to encrypt the data at transmit and again decrypt the data at receiver. The recipient uses the PGP and DES public keys to decrypt the specified received data (Riggs, 2004).
2.3 Authorization:
The process of authorizing the user by their personality to make use of the network capital is known as Authorization (M. Gupta, 2003).
There are 3 types of VPN technologies in presence such as VPN Intranet, VPN Extranet and the Remote VPN.
2.4 Intranet VPNs:
Intranet is very expensive as it need two routers connecting distant sites of an intranet company. The organization, functioning and maintanance of backbone intranet is very costly and as well depends upon on the stream of traffic and the whole intranet architecture (M.D Wilson, 2002). This expensive advance can be conquer by the VPN presentation which is a inexpensive internet connectivity.
2.5 Extranet VPNs:
In this stir to access the necessary resources of network for the exterior trade entity like clients, suppliers and partners playing a major part for deal organisations. The extranet connectivity which is a expensive as every system of intranet is modified taken sign of external network. To beat this the VPNs can be made-up for extranet which is easy and also low-cost.
2.6 Remote Access:
To admittance remotely, telecom and mobile contact users uses company resources of a network is known as remote access VPNs.
Figure: Remote access without the VPN (www.vietcert.net/VPN_Uni_files/image001.jpg)
The main mechanism to remote access group switched as made known in the above figure are:
- Remote Access Server: It is located at head quarters which authenticate the access to remote access.
- Dial up link is complete at main site for unlike charges as for the order to long space it is exceedingly charged.
3.0 WAN Routing Protocols:
3.1 ATM:
ATM is the abbreviation for Asynchronous Transfer Mode. Circuit switching usually requires that packets are placed into position in recurring frames. Asynchronous transmission allow cells to be placed anywhere in the data stream. I.e. synchronous, in time, in step according to use and/or network clocks.ATM at present has speed of 155Mbps (OC-3 ports), 622Mbps (OC-12 ports), 1.2 Gbps and 2.5 Gbps. Since the cells are rigid in length (53 octets, or bytes) quite variable such as an Ethernet frames, which can be switch in hardware to a certain extent than software and these in turn allows attaining the high speeds than Ethernet, Token Ring and FDDI. ATM is very lithe and allows transmission of different media types like voice, data files, video etc. All in turn demanding the network in different ways , video for example can be extremely subject to a sudden slowdown in network routine as altering speed video is very altering.ATM allows set up at the same time,depending upon the circuits with certain bandwidths and differing (http://www.rhyshaden.com/atm.htm). Quality of Service (QoS) can be locating up and is certain at connection stage by means of parameter base on the function and the position of the network at the moment of connection such as delay, delay jitter and error rate. Two priority for traffic are defined as: High priority
- Low priority: Low priority traffic force is leftover if around are switch congestion trouble. Particularly voice and video traffics include to be transferred by means of previous methods such as MPLS over ATM and IP over ATM, where QoS maintain advantages of the ATM are subjugated in exacting (Cemal Kocak, et.al, 2007). There is no joint media or conflict based protocols in ATM, each machine has 155Mbps all to itself. In ATM you be able to multiplex 'cell streams' so as to may be for totally different application, the structure works in 'connection oriented' form thereby guarantee cell sequencing for those cells in a exacting connection.
3.2 Frame Relay:
Frame Relay is developed by the values or technology base on ISDN (Piliouras, 2005). The communication is among end users by following the interface of public network and private network (Taylor, 2000). It handles high traffic on internet at high speeds and on the whole handles data networking issue at high speed by functioning on following principles. Frame relay consists of an efficient data transmission techniques used to send digital information. Relay race like system in which frames (data packets) are passed from one or many start points to one or many destinations via a series of intermediate node points.
As a WAN protocol, the most commonly implemented at layer 2(frame relay) of the open systems interconnection (OSI) seven layer model
There are 2 types of circuits:
- Permanent virtual circuits (PVC's) which are used to form logical end-to-end links mapped over a physical network
- Switched virtual circuits: (SVCs). The latter are analogous to the circuit-switching concepts of the public switched telephone network (PSTN), the global phone network.
3.3 Synchronous optical networking (SONET) and Synchronous Digital Hierarchy (SDH):
Standardized multiplexing protocols that transfer multiple digital bit streams over optical fiberusing lasers or light-emitting diodes (LEDs).This method was developed to replace the Plesiochronous digital hierarchy (PDH) system for transporting larger amounts of telephone calls and data traffic over the same fibre without synchronization problems. Lower rates can be transferred via an electrical interface.
SONET and SDH actually designed to transport circuit mode communications from a variety of different sources. Prior to SONET, the primary difficulty in doing this was actually operating at a slightly different rate and with different phase .SONET , within one single framing protocol allowed for the simultaneous transport of many different circuits. SONET is not a communication protocol in itself. SONET was the obvious choice for transporting Asynchronous Transfer Mode (ATM) frames due to its essential protocol neutrality oriented features; moreover it quickly evolved mapping structures and concatenated payload containers to transport ATM connections. In other words for ATM, (and for other protocols like TCP/IP and Ethernet) ,the internal complex structure previously used to transport circuit oriented connections is replaced by removing the large and concatenated frame such as STS- 3c into which ATM frames ,IP packets or Ethernet are placed.
SDH and SONET are used worldwide today. SONET being used in the U.S. and Canada and SDH in the other countries of the world thereafter respectively. SONET is considered the variation though the SONET standards were developed before SDH; their relative penetrations in the worldwide market dictate this thing. The protocol is an extremely heavily multiplexed structure, data interleaved with the header in between in a complex way. This is in order to permit the encapsulated data to have its own frame rate and to be able to float around relative to SDH /SONET frame structure and rate. For the encapsulated data, this interleaving permits a very low latency. Compared to the frame rate of 125 micro seconds and many competing protocols buffer the data for at least one frame or packet before sending it, data can be delayed by at most 32 micro seconds .To move within the overall framing due to it being on a different clock than the frame rate. Extra padding is allowed for the multiplexed data t he decision to allow this at most of the levels of the multiplexing structures gives high all around performance ,though it makes protocol complex. . Defined by the ANSI T1 for synchronous operation used in North America, SONET is the standard
3.4 Point-to-Point Protocol:
Point-to-Point Protocol, or PPP, is a data link protocol commonly used to establish direct connections between two networking nodes .it can provide connection authentication. Transmission encryption privacy and compression
over many types of physical networks including serial, cable, phone ,trunk line ,cellular customer dial up access to the internet most internet service providers use PPP. Internet service providers(ISPs) use two encapsulated form of PPP ,Point –to- Point over Ethernet and Point to point protocol over ATM are used by Internet service providers (ISP) to connect Digital Subscriber Line DSL Internet service.
Over synchronous and asynchronous circuits PPP is commonly used as data link layer protocol for connection .where it has largely superseded the older ,non standard Serial Line Internet Protocol (SLIP) and telephone company mandated standards ,including the internet protocols (IP) PPP was designed to work with numerous network player protocols .
Over broadband connections PPP is used. The result is the compression, authentication, encryption and much more, defining a complete method for robust data link connectivity between units using serial lines. Including error detection, it includes capabilities and features .Though PPP is called a protocol and is considered part of TCP/IP. It is based on procedures defined in many individual protocols.
3.5 ISDN:
The replacement for old age analogy technology is the ISDN. It was implemented to create a more reliable and faster transport mechanism. It is cheaper than a leased line and it takes seconds to install it. The standard ISDN, Broadband ISDN is the version most people are aware of which is the ATM.( Comparison of WAN Technologies, Syed Khundmir, CITM12 Assignment 1, University of Sunderland, 2009). The end equipment protocol is defined by the ITU I and the switch/network protocol is defined by the ITU Q series.
Structure of ISDN
The protocol model for ISDN is represented in the following diagram:3.6 Public Data Network (PDN):
The people around the world use public network to send and receive data which is also known as internet. If a user is making a call using the internet then its priority will be high because the user is using an expensive technology. If its security and reliability is ignored then more and more private networks will be formed by different companies which will lead to congestion of the network. The common carrier subscriptions which own telecom services are known as public networks (Comparison of WAN Technologies, Syed Khundmir, CITM12 Assignment 1, University of Sunderland, 2009). It supports the transmission of voice traffic over the internet using the modems through the telephone sockets and gain automated access to users around the world. In this there is no wastage of bandwidth as the calls are being made over the internet and this will be a reliable and suitable for small companies.
X.25 is a protocol used for WAN communication that defines connections between user devices and network devices established and maintained. X.25 is designed to operate effectively regardless of type of systems connected to the network, used in packet switched networks .In 1970s the common carriers developed the X.25 .during that time, WAN protocols weren't in need of being capable of providing connectivity across public data networks. Administered as an international standards by ITU-T
There are three categories into which network devices fall:
- Data terminal equipment(DTE)
- Data circuit- terminating equipment(DCE)
- Packet –Switching exchange(PSE)
Packet Assembler/Disassembler
PAD is used when a DTE device like character mode terminal, is too simple to implement the full X.25 functionality, it is commonly found in X.25.3.7 SDLC:
SDLC is second layer protocol for the systems network architecture of IBM's. Error corrections as well as multipoint links are supported by SDLC. There is an assumption under which it runs that there is a SNA header is present after every SDLC header. Many vendors use and implement SDLC on different platforms but it was mainly used by IBM mainframe systems. The use of SDLC is becoming rare and is mostly being replaced by IP based protocols. SDLC can operate on point to point and loop facilities and it even operates independently on communication links. It does not require the line to be switched or dedicated, two-wire or four wires, full duplexer or half duplexer operated. There is a unique ability of SDLC in which it mixes half-duplex secondary stations with full-duplex primary stations on four-wire circuits hence reducing the costs.
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