Unit 6 - Networks and the Internet

Advanced Research Projects Agency. U.S. Government research

A local area network where all computers within a physical location are connected to.

Unshielded Twisted Pair. It is a cable for networking computers together and has an RJ-45 connector.

The simplest of network devices. It takes the signal from one cable and splits it out to several others. With four out-signals it would be a four port hub. Sending information back is sending it through the uplink connection.

Similar to a hub but has basic filtering of data. Switches can prevent e.g. a broadcast storm, making sure data sent to the broadcast address is only sent to the ones that can receive it.

An intelligent networking device. It can filter data, block it, and ensures data is only sent to the correct destination.

Star topology.

A ring of devices connected together. Each computer passes all signals along, and it is not fault-tolerant.

Every node is connected to every other node. Very fault-tolerant but requires lots of cabling.

A central hub or switch that sends traffic to all outer node. It is fault-tolerant unless the central hub fails.

All computers are connected to the bus, and if a connection is broken the entire network fails. Not fault tolerant, but is used in some network backbones.

A topology that combines multiple topologies.

Device physically limited by a cable Relatively easy to troubleshoot Fast data speeds Very secure

Device can move freely within range Can be difficult to troubleshoot Medium data speeds Easy to intercept (hack) the signal) Only requires a wireless access point (and wireless support on the device)

Institute of Electrical and Electronics Engineers. An organization providing technical standardization for wireless networks among other things.

The standard for WiFi. Going up to 802.11ac which allows up to 3Gbps speeds over 2.4 and 5GHz frequencies.

Seven

P – Physical Layer is the physical devices and electrical signals. Hubs, switches, routers, cabling. Wireless frequencies, bit rate control

D – Data Link Layer responsible for formatting electrical signals into data, local network error checking including collisions (collision detection). MAC (Medium Access Control), Logical Link Control (LLC), PPP (Point-to-Point Protocol)

N – Network Layer responsible for routing data via IP-address. Data is organized into packets.

T – Transport Layer sends and receives data using protocols and settings. TCP/UDP are in layer 4. TLS is partly in Layer 4, partly in layer 6.

S – Session Layer maintaining and communication for sessions (e.g. ports) DNS, name resolution protocols, user logon, session management.

P – Presentation Layer containing data formatting (e.g. Unicode) and encryption.

A – Application Layer containing user interface and applications.