Networking Quiz #1

Topology

A term used to describe how devices are connected and how messages flow from device to device.

OSI Model

Advantages: Provides a common language and reference point for network professionals. Divides networking tasks into logical layers for easier comprehension. Allows specialization of features at different levels. Aids in troubleshooting. Promotes standards of interoperability between networks and devices. Provides modularity in networking features (developers can change features without changing the entire approach). Disadvantages: OSI layers are theoretical and do not actually perform real functions. Industry implementations rarely have a layer-to-layer correspondence with the OSI layers. Different protocols within the stacks perform different functions that help send or receive the overall message. A particular protocol implementation may not represent every OSI layer (or may spread across multiple layers).

Media Access Control (MAC)

Also called physical address, is a unique identifier assigned to network interfaces for communications on the physical network segment.

Network Interface Cards (NIC)

Cable Formula- N(N-1)/2 Media Access Control Address (MAC Address) Each host has a unique name

Ring Topology

Connects neighboring nodes until they form a ring. Signals travel in one direction around the ring; each device on the network acts as a repeater to send the signal to the next device. Features: Installation requires careful planning to create a continuous ring. Isolating problems can require going to several physical locations along the ring. A malfunctioning node or cable break can prevent signals from reaching nodes further along on the ring. No terminators required all devices hang off the ring "token ring" network whoever has the token can talk One token is standard Typically not fault tolerant

Bus Topology

Consists of a trunk cable with nodes either inserted directly into the trunk or tapped into the trunk using offshoot cables called drop cables. Features: Signals travel from one node to all other nodes. A device called a terminator is placed at both ends of the trunk cable. Terminators absorb signals and prevent them from reflecting repeatedly back and from on the cable. It can be difficult to isolate cabling problems. Not Fault tolerant machines past a break in the cable will not be connected to the server terminator prevents networks from "echoing" feed back loop

Logical Link Control (LLC)

Data communication protocol layer is the upper sublayer of the data link layer

Data Link Layer

Defines the rules and procedures for hosts as they access the physical layer. These rules and procedures specify or define: How hosts on the network are identified (physical or MAC address). How and when devices can transmit on the network medium (media access control and logical topology). How to verify that the data received from the physical layer are error free (parity and CRC). How devices control the rate of data transmission between hosts (flow control). Data at this layer are referred to as frames.

Networking Layer

Describes how data are routed across networks and on to the destination. Network layer functions Include: Identifying hosts and networks by using logical addresses. Maintaining a list of known networks and neighboring routers. Determining the next network point to which data should be sent. Routers use a routing protocol that takes into account various factors, such as the number of hops in the path, link speed, and link reliability, to select the optimal path for data. Data at this layer are referred to as packets.

Physical Topology

Describes the way a network is wired.

Logical Topology

Describes the way in which messages are sent.

Mesh Topology

Exists when there are multiple paths between any two nodes on a network. Created using point-to-point connections. This increases the network's fault tolerance because alternate paths can be used when one path fails. Two variations of mesh topologies exist: Partial Mesh- Some redundant paths exist. Full Mesh- Every node has a point-to-point connection with every other node. Full mesh topologies are usually impractical in a standard LAN, because the number of connections increases dramatically with every new node added to the network. A separate network interface and cable for each host on the network is required. However, a full mesh topology is commonly used to interconnect routers, providing alternate paths should one path go down or become overloaded. Mesh networks are also commonly used to create redundant paths between access points in a wireless network, providing alternate paths back to the wireless controller should one access point go down or become overloaded. With this topology, every access point can communicate directly with any other access point on the wireless network. Any device on the network can talk to any other device on the network. Is the ultimate in fault tolerant.

Presentation Layer

Formats or "presents" data into a compatible form for receipt by the Application layer or the destination system. Specifically, the Presentation layer ensures: Formatting and translation of data between systems Negotiation of data transfer syntax between systems by converting character sets to the correct format. Encapsulation of data into message envelopes by encryption and compression. Restoration of data by decryption and decompression.

Fault tolerant

If the network has a fault/break in it, does part of the network still function?

OSI Layers

Layer 1- Physical- Please Layer 2- Data- Do Layer 3- Network- Not Layer 4- Transport- Throw Layer 5- Session- Sausage Layer 6- Presentation- Pizza Layer 7- Application- Away

Session Layer

Manages the sessions in which data are transferred. Session layer functions include: Management of multiple sessions (each client connections is called a session). A server can concurrently maintain thousands of sessions. Assignment of a session ID number to each session to keep data streams separate. The setting up, maintenance, and tearing down of communication sessions.

Metropolitan Area Network (MAN)

Network that is typically managed by a city as a public utility.

Transport Layer

Provides a transition between the upper and lower layers of the OSI model, making the upper and lower layers transparent from each other. Transport layer functions include: End-to-end flow control Port and socket numbers Segmentation, sequencing, and combination Connection services, either reliable (connection-oriented) or unreliable (connectionless) delivery of data. Data at this layer are referred to as segments.

Physical Layer

Sets standards for sending and receiving electrical signals between devices. Protocols at the Physical layer identify: How digital data (bits) are converted to electric pulses, radio waves, or pulses of light. Specifications for cables and connectors. The physical topology Data at this layer are referred to as bits.

Star Topology

Uses a hub or switch to connect all network connections to a single physical location. Today it is the most popular type of topology for a LAN. Features: All network connections are located in a single place, which makes it easy to troubleshoot and reconfigure. Nodes can be added to or removed from the network easily. Cabling problems usually affect only one node. Has a central network appliance All devices are then run off that central appliance Star Network is fault tolerant Cost effective One NIC per PC

Application Layer

Whatever application that you are working with Includes: HTTP Telnet FTP TFTP SNMP

Peer-to-Peer

You have implemented a network where each device provides shared files with all other devices on the network

Client-Server

You have implemented a network where hosts are assigned specific roles, such as for file sharing and printing. Other hosts access those resources but do not host services of their own

Vampiric Tap

it was a vice with two taps