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Network Topology
Ring Topology:
Has a series of devices connected by unindirectional transmission links, that forms a ring. Each node is dependent upon the preceding nodes and if one system failed, all other systems could fail.
Bus Topology:
A single cable runs the entire length of the network. Each node decides to accept, process or ignore the packet. The cable where all nodes are attached is a potential single point of failure.
Linear bus - Has a single cable with nodes attached to it.
Tree topology - Has branches from the single cable and each branch can contain many nodes.
Star Topology:
All nodes connect to a central hub or switch. Each node has a dedicated link to the central hub.
Mesh Topology:
All systems and resources are connected to each other in a way that does not follow the uniformity of the previous topologies.
LAN Media Access Technologies
MTU - Is a parameter that indicates how much data a frame can carry on a specific network.
Token passing:
Is a 24-bit control frame used to control which computers communicate at what intervals. The token grants a computer the right to communicate. Do not cause collisions because only one computer can communicate at a time.
CSMA Carrier sense multiple access:
CSMA/CD (collision detection) - Monitor the transmission activity or carrier activity on the wire so that they can determine when would be the best time to transmit data. Computers listen for the absence of a carrier ton on the cable, which indicates that no one else is transmitting date at the same time.
Contention - The nodes have to compete for the same shared
medium
Collision - Happens when two or more frames collide.
Back-off algorithm - All stations will execute a random collision
timer to force a delay before they attempt to transmit data.
CSMA/CA (collision avoidance) - Is an access method where each computer signals its intent to transmit data before it actually does so.
Collision Domains:
Is a group of computers that are contending or competing for the same shared communication medium.
Polling:
Some systems are configured to be primary stations and others are secondary stations. At predefined intervals, the primary station will ask the secondary station if it has anything to transmit.
Protocols
ARP - Knows the IP address and broadcasts to find the matching hardware address, the MAC address.
RARP - Knows the hardware address and broadcasts to find the IP address.
Masquerading attack - An attacker alter a system's ARP table so that it contains incorrect information (ARP table poisoning).
DHCP - A computer depends upon a server to assign it the right IP address.
BOOTP -Can receive a diskless computers IP address from a server
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