Comp Network pre-study- Ethernet, wireless LAN, socket programming, & distributed applications Flashcards
Fast Ethernet extends traditional Ethernet performance up to 100 Mbps, and Gigabit Ethernet, up to _____ Mbps. Although they aren’t available to the average consumer, 10 Gigabit Ethernet (10,000 Mbps) now powers the networks of some businesses, data centers, and Internet2 entities. Generally, however, the expense limits its widespread adoption.
1,000
Ethernet cables likewise are manufactured to any of several standard specifications. The most popular Ethernet cable in use, Category 5 (CAT5 cable) supports both traditional and Fast Ethernet. Category 5e (CAT5e) and CAT6 cables support _______ _____.
Some devices without Ethernet support can support Ethernet connections using dongles such as USB-to-Ethernet adapters. Ethernet cables use connectors that look like the RJ-45 connector used with traditional telephones.
Gigabit Ethernet
Traditional Ethernet employs a bus topology, meaning that all devices or hosts on the network use the same shared communication line. Each device possesses an Ethernet address, also known as a ______ _______. Sending devices use Ethernet addresses to specify the intended recipients of messages.
MAC address
Data sent over Ethernet exists in the form of _____. An Ethernet frame contains a header, a data section, and a footer with a combined length of no more than 1,518 bytes. The Ethernet header contains the addresses of both the intended recipient and the sender.
frames
Data sent over the Ethernet is automatically broadcast to all devices on the network. By comparing the Ethernet address against the address in the frame header, each Ethernet device tests each frame to determine if it was intended for it and reads or discards the frame as appropriate. ___ ____ incorporate this function into their hardware.
Network adapters
Devices that want to transmit on an Ethernet network first perform a preliminary check to determine whether the _______ is available or if a transmission is in progress. If the Ethernet is available, the sending device transmits onto the wire. It’s possible, however, that two devices will perform this test at approximately the same time and both _______ simultaneously.
medium
transmit
By design, as a performance tradeoff, the Ethernet standard does not prevent multiple simultaneous transmissions. These so-called collisions, when they occur, cause both transmissions to fail and require both sending devices to retransmit. ______ uses an algorithm based on random delay times to determine the proper waiting period between retransmissions. The network adapter also implements this algorithm.
Ethernet
protocol for broadcasting, listening, and detecting collisions is known as CSMA/CD (carrier sense multiple access/collision detection). Some newer forms of Ethernet do not use CSMA/CD. Instead, they use the _________ Ethernet protocol, which supports point-to-point simultaneous sending and receiving with no listening required.
full-duplex
Ethernet cables are limited in their reach, and those distances (as short as 100 meters) are insufficient to cover medium and large network installations. A repeater in Ethernet networking allows multiple cables to be joined and greater distances to be spanned. A ______ ______ can join an Ethernet to another network of a different type, such as a wireless network. One popular type of repeater device is an ______ _____. Other devices sometimes confused with hubs are switches and routers.
bridge device
Ethernet hub
_____ _____ _____ also exist in multiple forms. Computers and game consoles feature built-in Ethernet adapters. USB-to-Ethernet adapters and wireless Ethernet adapters also can be configured to work with many devices.
Ethernet network adapters
How does a WLAN work?
Like broadcast media, a WLAN transmits information over _____ _____. Data is sent in packets. The packets contain layers with labels and instructions that, along with the unique MAC (Media Access Control) addresses assigned to endpoints, enable ______ to intended locations.
radio waves
routing
A WLAN can be configured in one of two ways:
A home or office Wi-Fi network is an example of a WLAN set up in infrastructure mode. The endpoints are all connected and communicate with each other through a base station, which may also provide internet access.
A basic infrastructure WLAN can be set up with just a few parts: a wireless router, which acts as the base station, and endpoints, which can be computers, mobile devices, printers, and other devices. In most cases, the wireless router is also the internet connection.
A WLAN is more vulnerable to being breached than a physical network. With a wired network, a bad actor must gain physical access to an internal network or breach an external firewall. To access a WLAN, a bad actor must simply be within range of the network.
The most basic method of securing a WLAN is to use _____ addresses to disallow unauthorized stations. However, determined adversaries may be able to join networks by _____ an authorized address.
The most common security method for a WLAN is encryption, including _____ _____ _____ (WEP) and Wi-Fi Protected Access (WPA), with WPA2 as the standard authentication method.
MAC
spoofing
Wired Equivalent Privacy
How does roaming work on a WLAN?
For any sized network, access points can extend the area of access.
Wi-Fi standards are designed to allow a nonstationary user’s connection to jump from one access point to another, though some users and applications may experience brief dropouts. Even with nonoverlapping access points, a user’s connection is simply paused until connection with the next access point.
Additional access points can be wired or wireless. When access points overlap, they can be configured to help optimize the network by sharing and managing loads.
A _____ _____ extends a WLAN’s reach and performance, through the use of numerous access points that connect with each other wirelessly. A mesh network provides multiple transmission paths; with intelligent algorithms, it can manage routing to improve performance.
mesh network
