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Fundamentals of Ethernet LANs


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Ethernet
The term __ refers to a family of LAN standards that together define the physical and data link layers of the world’s most popular wired LAN technology.
Ethernet LAN switch
First, the LAN needs a device called an __, which provides many physical ports into which cables can be connected.
Ethernet cables
The LAN uses __ to connect different Ethernet devices or nodes to one of the switch’s Ethernet ports.
wired
Ethernet defines __ LAN technology only; in other words, Ethernet LANs use cables.
IEEE 802.11
Wireless LANs, defined by the __ using standards that begin with __, use radio waves to send the bits from one node to the next.
access point
Most wireless LANs rely on yet another networking device: a wireless LAN __.
AP
The __ acts somewhat like an Ethernet switch, in that all the wireless LAN nodes communicate with the Ethernet switch by sending and receiving data with the wireless AP.
IEEE 802.3
All Ethernet standards come from the __ and include the number __ as the beginning part of the standard name.
copper wires glass fibers
The most fundamental cabling choice has to do with the materials used inside the cable for the physical transmission of bits: either __ or __.
Unshielded Twisted Pair
The use of __ cabling saves money compared to optical fibers, with Ethernet nodes using the wires inside the cable to send data over electrical circuits.
Fiber-optic
__ cabling, the more expensive alternative, allows Ethernet nodes to send light over glass fibers in the center of the cable.
suffix letters
The IEEE defines Ethernet physical layer standards using a couple of naming conventions. The formal name begins with “802.3” followed by some __.
UTP fiber
The IEEE also uses more meaningful shortcut names that identify the speed, as well as a clue about whether the cabling is __ (with a suffix that includes “T”) or __ (with a suffix that includes “X”).
fiberglass light
Fiber-optic cabling contains long thin strands of __. The attached Ethernet nodes send __ over the glass fiber in the cable, encoding the bits as changes in the __.
Ethernet Fast Ethernet Gigabit Ethernet
The three most commonly used Ethernet standards: 10BASE-T (__), 100BASE-T (__), and 1000BASE-T (__)
UTP electricity
While it is true that Ethernet sends data over __ cables, the physical means to send the data uses __ that flows over the wires inside the cable.
loop
An electrical circuit requires a complete __, so the two nodes, using circuitry on their Ethernet ports, allowing electricity to flow.
encoding scheme
To send data over UTP cables, the two devices follow some rules called an __. The idea works a lot like when two people talk, using the same language.
electromagnetic interference
When electrical current passes over any wire, it creates __ that interferes with the electrical signals in nearby wires, including the wires in the same cable.
crosstalk
EMI between wire pairs in the same cable is called __.
Ethernet link
The term __ refers to any physical cable between two Ethernet nodes.
two pairs four pairs
The 10BASE-T and 100BASE-T standards require __ of wires, while the 1000BASE-T standard requires __.
RJ-45
Many Ethernet UTP cables use an __ connector on both ends.
eight pin positions
The RJ-45 connector has __ physical locations into which the *** wires in the cable can be inserted, called __.
Ethernet port
To complete the physical link, the nodes each need an RJ-45 __ that matches the RJ-45 connectors on the cable so that the connectors on the ends of the cable can connect to each node.
network interface card
PCs often include this RJ-45 Ethernet port as part of a __, which can be an expansion card on the PC or can be built into the system itself.
Switches
__ typically have many RJ-45 ports because they give user devices a place to connect to the Ethernet LAN.
RJ-11
The RJ-45 connector is slightly wider, but otherwise similar, to the __ connectors commonly used for telephone cables in homes in North America.
gigabit interface converter
Cisco switches include some physical ports whose port hardware can be changed later, after you purchase the switch. One type of port is called a __.
10BASE-T 100BASE-T
__ and __ use two pair of wires in a UTP cable, one for each direction.
1 2 3 6
As a rule, Ethernet NIC transmitters use the pair connected to pins __ and __; the NIC receivers use a pair of wires at pin positions __ and __.
receivers transmitters
LAN switches, knowing those facts about what Ethernet NICs do, do the opposite: Their __ use the wire pair at pins 1 and 2, and their __ use the wire pair at pins 3 and 6.
straight-through
To allow a PC NIC to communicate with a switch, the UTP cable must also use a __ cable pinout.
pinout
The term __ refers to the wiring of which color wire is placed in each of the eight numbered pin positions in the RJ-45 connector.
crossover
When two like devices connect to an Ethernet link, they both transmit on over the same pins. In that case, you then need another type of cabling pinout called a __ cable.
crossover
If the endpoints transmit on the same pin pair, we should use __ cable.
straight-through
If the endpoints transmit on different pin pairs, we should use __ cable.
PC NICs, Routers, Wireless access points
Devices that Transmit on Pins 1,2:
Hubs, Switches
Devices that Transmit on Pins 3,6:
auto-mdix
Cisco switches have a feature called __ that notices when the wrong cable is used and automatically changes its logic to make the link work.
four advanced electronics
1000BASE-T requires __ wire pairs. It uses more __ that allow both ends to transmit and receive simultaneously on each wire pair.
4 5 7 8
The 1000BASE-T straight-through cable keeps one pair at pins 1 and 2 and another at pins 3 and 6, just like in the earlier wiring. It adds a pair at pins __ and __ and the final pair at pins __ and __.
header encapsulated data trailer
The Ethernet data link protocol defines the Ethernet frame: an Ethernet __ at the front, the __ in the middle, and an Ethernet __ at the end.
Preamble 7
Synchronization
Start Frame Delimiter 1
Signifies that the next byte begins the Destination MAC Address field
Destination MAC Address 6
Identifies the intended recipient of this frame
Source MAC Address 6
Identifies the sender of this frame
Type 2
Defines the type of protocol listed inside the frame; today, most likely identifies IP version 4 (IPv4) or IP version 6 (IPv6)
Data and Pad 46-1500
Holds data from a higher layer, typically an L3PDU (usually an IPv4 or IPv6 packet). The sender adds padding to meet the minimum length requirement for this field (46 bytes).
Frame Check Sequence 4
Provides a method for the receiving NIC to determine whether the frame experienced transmission errors.
error recovery
Note that error detection does not also mean __.
TCP
Other protocols, notably __, recover the lost data by noticing that it is lost and sending the data again.
46 1500
The IEEE 802.3 specification limits the data portion of the 802.3 frame to a minimum of __ and a maximum of __ bytes.
maximum transmission unit
The term __ defines the maximum Layer 3 packet that can be sent over a medium.
source address destination address
The sending node puts its own address in the __ field and the intended Ethernet destination device’s address in the __ field.
Media Access Control 6-byte-long
Ethernet addresses, also called __ addresses, are __ binary numbers.
12-digit
For convenience, most computers list MAC addresses as __ hexadecimal numbers.
unicast
Most MAC addresses represent a single NIC or other Ethernet port, so these addresses are often called a __ Ethernet address.
organizationally unique identifier
Before a manufacturer can build Ethernet products, it must ask the IEEE to assign the manufacturer a universally unique 3-byte code, called the __.
global MAC addresses
The IEEE also calls these universal MAC addresses __.
LAN address hardware address
Ethernet addresses go by many names: __, Ethernet address, __, burned-in address, physical address, universal address, or MAC address.
universal address
The IEEE uses the term __ to emphasize the fact that the address assigned to a NIC by a manufacturer should be unique among all MAC addresses in the universe.
burned-in address
The term __ refers to the idea that a permanent MAC address has been encoded (burned into) the ROM chip on the NIC.
Group addresses
__ identify more than one LAN interface card. A frame sent to a __ might be delivered to a small set of devices on the LAN, or even to all devices on the LAN.
Broadcast address FFFF.FFFF.FFFF
Frames sent to this address should be delivered to all devices on the Ethernet LAN. It has a value of __.
Multicast addresses
Frames sent to this address should be copied and forwarded to a subset of the devices on the LAN that volunteers to receive frames.
Half-duplex
Logic in which a port sends data only when it is not also receiving data; in other words, it cannot send and receive at the same time.
Full-duplex
The absence of the half-duplex restriction.
physical 1
LAN hubs forward data using __ layer standards, and are therefore considered to be Layer __ devices.
repeats
When an electrical signal comes in one hub port, the hub __ that electrical signal out all other ports (except the incoming port).
collides garbled
The downside of using LAN hubs is that if two or more devices transmitted a signal at the same instant, the electrical signal __ and becomes __.
floods
The hub __ each frame out all other ports (except the incoming port).
queue
A switch would look at the MAC addresses, and even if the switch needed to forward both frames to Larry, the switch would send one frame and __ the other frame until the first frame was finished.
CSMA/CD
Nodes that use half-duplex logic actually use a relatively well-known algorithm called __.
jamming signal
They send a __ that tells all nodes that a collision happened.
half-duplex
However, for any link connected to a LAN hub, the connected LAN switch and NIC port should use __.