Topology of LANs

Topology of Lan-

                A bus network is the simplest method used to network computers.  A bus network consists of a single cable that connects all computers, servers, and network peripherals in a single network segment. Hosts on a bus network communicate with each other by putting information on the cable addressed to the physical address of the network card used to connect the destination computer to the segment.  This physical address is called the Media Access Control (MAC) address.

Network card and MAC Address-

Each network card is assigned a unique MAC address. MAC addresses are 12-digit hexadecimal addresses such as 00-01-0E-6F-6D-62.  Each network card manufacturer is assigned a prefix to be used for  its network cards. It is the responsibility of the network card manufacturer to be sure no two of its cards have the same MAC address.

Server Based Network-

                In server-based networks, at least one host is dedicated to server functionality. Client computers do not share any information with other computers.  All data is stored on the central server.  Most corporate networks are based on this methodology. Within a server-based network, servers can play several roles. These roles include the following:

·         Directory Servers:These provide a central directory service for management of users,  groups, and host objects to allow for centralized authentication and authorization using the central directory.

·         File and Print Servers:  These provide a secure repository for all data.  They also can manage printqueues that provide access to network-sharable print resources.

·         Application Servers:  These provide the server side of client/server applications. In a client/server environment, the client runs a small version of the program that allows connectivity to the server.  The server side of the application is used to perform processor-intensive queries on behalf of the client.  Example of application servers includes Web servers and database servers.

·         Mail Servers:  These provide electronic-message capabilities for the clients of the network.  With the use of gateways, mail transport can take place between heterogeneous mail systems.

·         Security Servers:  These provide security to the local area network if it is connected to any larger networks such as the Internet.  Security servers include firewalls and proxy servers.

·         Remote Access Servers:     These enable external data flow to occur between the network and remote clients.  A remote client can use a modem to dial in to the local area network, or alternatively use a technology known as tunneling or Virtual Private Networks (VPNs) to connect to the remote network over a public network such as the Internet.  The system that allows the remote client to connect to the corporate network is the remote access server.  A remote access to the network, or one or more virtual ports to allow tunnel connections. After the client has connected to the remote network, the user can function as if he or she were directly connected to network using a network card.

Peer-to-Peer network

Peer-to-Peer networks-

                              Peer-to-Peer networks operate with no dedicated servers on the network.  Each host functions as both a client and a server.  The user at each host determines what information or peripherals he is willing to share with the other members of the network.  Peer-to-Peer networks generally are relegated to smaller organizations; they do not scale well to larger ones.  They have several security issues as a result of each host’s capability to control its own security, which decentralizes security control.

Wide Area Networks (WANs)-

                LAN implementations have physical and geographic limitations.  Wide area networks (WANs) meet a need for networking that requires connectivity over larger distances.

                Most WAN are simply combinations of local area networks and additional communications links between the LANs.  The following terms are used to dercribe the scope or size of a WAN:

·         Metropoliton Area Networks (MANs)-  MANs are WANs is a small geographic area.  Generally, they are localized to single city or region.

·         Campus area networks (CANs)-  CANs  is a common designation for WANs that link regions of a university campus.

For practical implementation, these are no different from a wide area network except for the area they physically cover.  

                Communications over a WAN use one of the following transmission technologies:

·         Analog

·         Digital

·         Packet Switching

Analog and digital technologies commonly are implemented as point-to-point technologies.  In other words, they are configured between two distinct hosts.  Packet switching, on the other hand, links several hosts using a mesh or cloud technology.  Any host participating in t;he cloud can establish a session to another host in the cloud.

Analog WAN Connectivity-

                Analog phone lines can be used to connect networks despite the poor line quality and slower speeds.  The public switched telephone network (PSTN) was primarily designed for voice traffic; it also can be used for data traffic.  Remote users connecting to the home network from the road often use PSTN access.  Although it is possible to purchase a dedicated analog line to connect networks, the cost of a conditioned line generally is prohibitive, and other networking solutions are investigated.

Digital Wide Area Network Connectivity-

                A more common method of linking a WAN is to use digital data service (DDS) lines.  DDS provides a point-to-point synchronous connection.  A company can lease dedicated circuits that provide full-duplex bandwidth by setting up a permanent link from each endpoint of the network.

                Digital lines are preferable to analog lines due to increased speed and lack of transmission errors.  Digital traffic does not require a modern Instead, data is sent from a router on a network to a channel service unit/data service unit (CSU/DSU).

                The following are common digital connectivity methods:

·         T1/E1

·         T3/E3

·         ISDN

·         Switched 56

T1/E1-  T1 service (known as E1 in Europe) is the most widely used digital service at higher data speeds.  T1 can transmit a full duplex signal at a rate of 1.544 Mbps.  It can be used to transmit voice, data, and video signals.

Because of the high cost of a T1 line, many subscribers opt for fractional-T1 service. Instead of using a T1’s full bandwidth, the subscriber uses one or more T1 channels, Each T1 channel is a 64Kbps increment.

T3/E3-  T3 service (known as E3 in Europe) can provide voice and data-grade service at speeds up to 45Mbps.  This is the highest-capacity service available to the consumer today.  As with T1 service, fractional-T3 service is available as an alternative to multiple T1 lines.

Integrated Services Digital Network(ISDN)-  ISDN is an inter LAN connectivity method that can carry data, voice and imaging signals.  Two flavors olf ISDN are available: basic rate and primary rate.
Basic rate ISDN provides two bearer channels (known as B Channels) that communicate at 56Kbps; an 8Kbps link-management channel; and one data channel (known as a D channel) that carry signal and link management data at a r ate of 16Kbps.  A network using both B channels can provide a 128Kbps data stream.

Primary rate ISDN provide the entire bandwidth of a T1 link by provide the entire bandwidth of a T1 link by providing 23B channels and one D Channel.  In Europe, 30B channels are used.  The D channel under primary rate ISDN communicates at 64Kbps and still is used only for signal and link management data.

ISDN is a demand-dial interface, Instead of remaining active at all hours, it demand-dials whenever a connection is required.

What is Local Area Network(LANs)

Local Area Network(LANs)-

                Local area Networks (LANs) are the most common networks.  A LAN has the following characteristics:

·         The network operates in a contained area.  This could be a single floor in a building or simply within a single building.

·         The host within the LAN is interconnected with high-bandwidth network connections such as Ethernet or token ring, or use newer technology such as wireless networks.

·         All facets of the LAN often are privately managed. No third parties are required for connectivity solutions.

·         LAN services are available on a 7-dayh, 24-hour basis.

Type of Network -

·         Peer-to-peer networks

·         Server-based networks

Peer-to-Peer networks-

                              Peer-to-Peer networks operate with no dedicated servers on the network.  Each host functions as both a client and a server.  The user at each host determines what information or peripherals he is willing to share with the other members of the network.  Peer-to-Peer networks generally are relegated to smaller organizations; they do not scale well to larger ones.  They have several security issues as a result of each host’s capability to control its own security, which decentralizes security control.

Server Based Network-

                In server-based networks, at least one host is dedicated to server functionality. Client computers do not share any information with other computers.  All data is stored on the central server.  Most corporate networks are based on this methodology. Within a server-based network, servers can play several roles. These roles include the following:

·         Directory Servers:These provide a central directory service for management of users,  groups, and host objects to allow for centralized authentication and authorization using the central directory.

·         File and Print Servers:  These provide a secure repository for all data.  They also can manage printqueues that provide access to network-sharable print resources.

·         Application Servers:  These provide the server side of client/server applications. In a client/server environment, the client runs a small version of the program that allows connectivity to the server.  The server side of the application is used to perform processor-intensive queries on behalf of the client.  Example of application servers includes Web servers and database servers.

·         Mail Servers:  These provide electronic-message capabilities for the clients of the network.  With the use of gateways, mail transport can take place between heterogeneous mail systems.

·         Security Servers:  These provide security to the local area network if it is connected to any larger networks such as the Internet.  Security servers include firewalls and proxy servers.

·         Remote Access Servers:     These enable external data flow to occur between the network and remote clients.  A remote client can use a modem to dial in to the local area network, or alternatively use a technology known as tunneling or Virtual Private Networks (VPNs) to connect to the remote network over a public network such as the Internet.  The system that allows the remote client to connect to the corporate network is the remote access server.  A remote access to the network, or one or more virtual ports to allow tunnel connections. After the client has connected to the remote network, the user can function as if he or she were directly connected to network using a network card.

Connecting To a Cisco Router

We can connect to a Cisco Router to configuration it, verify its configuration and check statics.  There are different way to this, but most after, the first place uou would connect to is the console post.  The console lpost is usually an RJ-45 (8-pin modules) default there's may or may not be a password set.  The new cisco as the password by default.

Note-   Auxalic Port is connected by modem.