Discussing The Use Of The OSI Model Information Technology Essay
Part A – Networks and Spheres
Write a description of the Layer 3 of the O.S.I theoretical account as implemented in an Ethernet LAN. A treatment of the ‘block size ‘ or domain size and schemes to pull off the size is required. The usage of RFC 1918 should be included. The work should be referenced with commendations. NON- Cisco beginnings should be used. Diagrams may be included.
Layer three of the OSI theoretical account is the Network bed this bed is where routers and some bed three switches operate, the intent of the bed is to happen the best way for packages of informations to make their finish. The web bed holds the information of the all environing nodes so informations can be transmitted to them in the fastest and most cost effectual manner. Other undertaking that the web bed performing artists are as follows mistake handling, package sequencing and web traffic control. For all the devices in the web to pass on with one another they must be given different and alone IP references from which they are identified. Unlike MAC turn toing in informations link bed IP addressing is non produced by the hardware developer, IP references are assigned by the web decision maker statically or dynamically via the usage of DHCP.
The web beds primary map is to happen a finish for informations, the finish of the package is normally the IP reference given in the package header. If the finish is straight connected to one of the router interfaces so the package is sent down the lower beds of the web device to the finish. For an Ethernet LAN layer 3 is needed when the web grows excessively big and the LAN can no longer map at functional velocities and the quality of the information is affected. To cut down the redundancy and hike the LAN public presentation informations web can be segmented utilizing a router, the web traffic so flows through the router using the shop and frontward logic. The strengths of using routing bed 3 are as follows ;
Routers can command traffic better as unnecessary information is restricted from being transmitted as routers merely frontward informations.
Assorted routing protocols can be implemented within the LAN together bettering web flexibleness.
Routers besides do non send on broadcast and multicasts as switches do so this reduces the hit sphere and increases LAN public presentation.
Each web section or hit sphere connected to the router will necessitate a different IP subnet. The size of the sphere intending the sum of clients in the sub-network will find the sum of IP reference that need to be assigned to each client. Two ways in which IP references can be assigned to the web are via utilizing either individual degree sub-netting or VLSM. To utilize individual degree sub-netting on a web the sizes of the spheres must be of similar, if they are non so configuring the web with IP references can blow a great figure of IP reference in the procedure. An illustration of this can be given ; a concern utilizing a category C web has its web segmented the size of each sphere is as follows, subnet one to four will incorporate 25 clients while subnet five will incorporate 50 host and subnet six will incorporate 60. In entire two and 20 reference are needed the lone manner in which to make this utilizing individual degree sub-netting is to get another category C block. A more productive manner the web can be divided is through VLSM with this the size of the subnets can be altered to the specifications of the specific spheres.
Businesss utilizing LANs normally restrict entrees to the cyberspace and utilize their ain resources, hence some administration use RFC1918 reference infinite. These address infinites are private as a consequence any administration can utilize them but if their web is connect to the wider community outside their administration this may do jobs. The private web scopes are as follows
10.0.0.0-10.255.255.255 ( 10/8 prefix )
172.16.0.0-172.31.255.255 ( 172.16/12 prefix )
192.168.0.0-192.168.255.255 ( 192.168/16 prefix )
Another usage for RFC1918 is for devices which require an IP reference but need non be connected to a broad country web such as pressmans. This manner valuable IP references can be saved for future proofing and development.
hypertext transfer protocol: //www.tech-faq.com/network-layer.html
hypertext transfer protocol: //compnetworking.about.com/od/basicnetworkingconcepts/l/blbasics_osi3.htm
hypertext transfer protocol: //www.webopedia.com/quick_ref/OSI_Layers.asp
hypertext transfer protocol: //www.windowsnetworking.com/articles_tutorials/OSI-Reference-Model-Layer3-Hardware.html
hypertext transfer protocol: //www.faqs.org/rfcs/rfc1918.html
hypertext transfer protocol: //www.tech-faq.com/understanding-ethernet-lan-segmentation.html
hypertext transfer protocol: //computer.howstuffworks.com/lan-switch15.htm
hypertext transfer protocol: //www.oucs.ox.ac.uk/network/rfc1918/
hypertext transfer protocol: //www.tcpipguide.com/free/t_IPVariableLengthSubnetMaskingVLSM.htm # Figure_70
Part B – Broadcasts
Write a description of Network Broadcasts with brief inside informations of no more than two common protocols that use airing. Describe schemes that may be used to forestall break to the LAN caused by broadcasts. The work should be referenced. NON- Cisco beginnings should be used. Diagrams may be included.
A web broadcast is a message which is sent from one device to all other devices on the local web. The manner in which the message is sent to all the hosts on the local web is via the usage of a broadcast reference which is the last reference of the subnet. The chief ground for broadcasts is to maintain up-to-date information within all devices on the web either that is IP or MAC references.
Protocols which use Broadcasts are RIP and DHCP all send changeless information across the web. RIP is a routing protocol it calculates the best path to a finish based on hop counts which is the distances and the sum of routers the informations will hold to go through. Broadcasts within RIP configured routers are sent every 30 seconds they contain an advertizement which allows the routers to recognize the environing topology. DHCP dynamically assigns IP references to web devices to make this it foremost
hypertext transfer protocol: //learn-networking.com/network-design/how-a-broadcast-address-works
Rip hypertext transfer protocol: //www.inetdaemon.com/tutorials/internet/ip/routing/rip/
hypertext transfer protocol: //www.mymacaddress.com/igrp-eigrp-ospf-isis-bgp/
hypertext transfer protocol: //articles.techrepublic.com.com/5100-10878_11-6169808.html