LAN Design
OSI Model
Layer 7 - Provides network processes to applications.
Layer 6 - Data representation and code formatting.
Layer 5 - Interhost communication.
Layer 4 - End to End connections.
Layer 3 - Addresses and best path.
Layer 2 - Access to media.
Layer 1 - Binary transmission.
Addressing
MAC addresses - Standardized data link layer address that is required for every port or device that connects to a LAN. Other devices in the network use these addresses to locate specific ports in the network and to create and update routing tables and data structures. MAC addresses are 6 bytes long and are controlled by the IEEE. Also known as a hardware address, a MAC-layer address, or a physical address.
IP addresses - 32-bit address assigned to hosts using TCP/IP. An IP address belongs to one of five classes (A,B,C,D, or E) and is written as 4 octets seperated with periods (dotted decimal format). Each address consists of a network number, and a host number. The network and subnetwork numbers together are used for routing, while the host number is used to address an individual host within the network or subnetwork. A subnet mask is used to extract network and subnetwork information from the IP address. Also called an Internet address.
IP Address Classes
Class A - 1-127 in the first octet. Used for government organizations use or large large companys.
Class B - 128 -191 in the first octet. Used for medium sized companys or organizations.
Class C - 192 - 223 in the first octet. Used from anything to personal or small businesses.
Class D - 224 - 239 Reserved for government use.
Class E - 240 - 254 Reserved for research use.
Ethernet
Congestion problems
- When there is an excessive amount of traffic on a network or network segment causing a lack in bandwidth.
Half-Duplex - Capable of sending data in only one direction at a time between a sending station and a receiving station.
Full-Duplex - Capable of simultanius data transmission between a sending and receiving station.
Fast Ethernet (features/benefits) - Any of a number of 100-mbs Ethernet specifications. Fast Ethernet offers a speed increase ten times that of the 10BaseT Ethernet specification, while preserving such qualities as frame format, MAC mechanisms, and MTU. Such similarities allow the use of existing 10BaseT applications and network management tools on Fast Ethernet networks. Based on an extension of the IEEE 802.3 specification.
Fast Ethernet (guidelines/distance limits) - Distance limit for CAT 5 is 100 meters. Such similarities allow the use of existing 10BaseT applications and network management tools on Fast Ethernet networks.
Network Segmentation using...
Bridges - Device that connects and passes packets between two network segments that use the same communications protocol. Segments using MAC addresses and forwards broadcasts out of all ports. Bridges operate at the OSI layer 2, and in general bridges will filter, forward, or flood an incoming frame based on the MAC address of that frame.
Routers - Segments with IP addresses and subnetwork masks. Network layer device that uses one or more metrics to determine the optimal path along which network traffic should be forwarded. Routers forward packets from one network to another based on network layer information. Routers do not forward broadcasts.
Switches - Network device that filters, forwards, and floods frames based on the destination address of each frame. Used in microsegmentation.The switch operates at the data link layer of the OSI model.<
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