week 2 networking Flashcards
sneakernet
moved the file by putting it on a disk and then moving that disk into another system (no network)
xerox invented first ethernot
802.3
ethernet commite thjat controls the ethernet standard still today
802.3i
10mbps ethernet usuing twisted pair cableing
802.3ab
gigabit ehernet over twisted pair
802.3by
25 Gigabit Ethernet over fiber
sending computers can resend damaged frames
preamble
a 7-byte series of alternating ones and zeroes followed by a 1-byte start frame
delimiter, always precedes a frame. The preamble gives a receiving NIC time to realize a
frame is coming and to know exactly where the frame starts. The preamble is added by
the sending NIC.
PAD
a frame has minnimum 64 bits of data if smaller the frame will (pad) the shortage with data too hit the 64
frame check sequence
enables ethernet nodes to recognize when bad things happen too good data
CRC
cyclic redundancy chek
cycle redundancy check
a mathmatical equation that has to nequal from the sent machine and reciving maching optherwise the frame is dropped
baseband
the cable only carries one type of signal
what cable did 10BaseT use ?
unshielded twisted pair
10BaseT summary
- Speed 10 Mbps
- Signal type Baseband
- Distance 100 meters between the hub and the node
- Node limit No more than 1024 nodes per hub
- Topology Star-bus topology: physical star, logical bus
- Cable type Cat 3 or better UTP cabling with RJ-45 connector
how does fiber optic send data?
puleses of light
10BaseFL
fiber optics cable
10BaseFL summary
- Speed 10 Mbps
- Signal type Baseband
- Distance 2000 meters between the hub and the node
- Node limit No more than 1024 nodes per hub
- Topology Star-bus topology: physical star, logical bus
- Cable type Multimode fiber-optic cabling with ST or SC connectors
what does a media converter do?
connects different ethernet types
csma/cd
carrier sense mutiopple access/ collision detection
carrier sense
each node usuing the network examines thew cable before sending a data frame
EXAM TIP CSMA/CD is a network access method that maps to the IEEE 802.3
standard for Ethernet networks.
mutiple access means
all machines have equal access otoo the wire
what happens if there is a collision?
both senders know that a collision ahppend they will wait arandom amount of tinme and check if the cable is free before resending
EXAM TIP Adding another hub or two to an early Ethernet network
enabled you to add more devices, but also compounded the problem with
collisions. In such a scenario, you could connect networks using a bridge.
A bridge acted like a repeater to connect two networks, but then went a
step further—filtering and forwarding traffic between those segments
based on the MAC addresses of the computers on those segments. This
placement between two segments preserved bandwidth, making larger
Ethernet networks possible. You’ll see the term “bridge” applied to modern
devices, primarily in wireless networking. The interconnectedness of
network segments is similar, but the devices are fundamentally different.
See Chapter 14 for the scoop on wireless.
switch
come with extra smarts that enable
them to take advantage of MAC addresses, effectively creating point-to-point connections between two conversing computers.
SAT
Source ADDRESS TABLE
once a switch gets an address what does it do
ity stores the address in the source address table
EXAM TIP One classic difference between a hub and a switch is in the
repeating of frames during normal use. Although it’s true that switches
initially forward all frames, they filter by MAC address in regular use. Hubs
never learned and always forwarded all frames.
what happens when 2 computers connect too a switch at the same time?
Each port on a switch is in its own collision domain, plus the switch can buffer incoming frames. That means that two nodes connected to the switch can send data at the same
time and the switch will handle it without any collision.
uplink port
enables the connection of 2 swqitches usuing straight through cable
bridging lopp[s or switching loops
redudent connections between switches on a network
STP
spanning trree proocal
spanning tree protocal
sensinsin loops before they hapopen
BPDU
Bridge protocal data units
Bridge protocal data units
switches communicate with other switches too stop bridges from happening