1.2 Flashcards
What is the network edge consist of?
hosts: client and servers
servers in data centres
What are access networks and physical media
wired, wireless communication links
What is the network core?
interconnected routers
network of networks
How would one connect end systems to an edge router?
Via residential access networks
institutional access networks(like schools and company networks)
mobile access networks(data?)
What is a DSL access network?
it uses existing telephone lines that connect to a central office DSLAM.
Thus data over DSL phone line goes to the internet and phone calls the DSL phone line goes to the telephone network
<2.5 Mbps upstream transmission (Typically < 1Mbps)
<24 Mbps downstream transmission rate (Typically < 10 Mbps)
How does a cable access network work?
Works with dedicated internet line(modem, router etc)
uses frequency division multiplexing(different data transferred to different frequency bands)
uses a hybrid fibre coax cable(up to 30 Mbps downstream transmission rate, 2 Mbps upstream transmission rate)
homes in cable network all attach to cable head unlike DSL which directly connects to access central office
What is an enterprise access network?
Typically used in companies/universities
10Mbps, 100Mbps, 1Gbps,10Gbps
Typically connect into Ethernet switch
What is a bit?
propagates between transmitter/receiver pairs
What is a physical link?
It is what lies between transmitter and receiver
What is guided media?
signals propagate in solid media: i.e copper, fiber,coax
What is unguided media?
signals propagate freely, i.e radio
What is a twisted pair?
two insulated copper wires
category 5100Mbps
category 6 10Gpbs
What is and How to calculate Packet Transmission Delay?
It is the time needed to transmit an L-bit packet into a link
L(bits)/R(bits/sec)
where L is the length of in bits of the packet being transmitted
and r is the transmission rate/capacity/link bandwidth for the speed at which the packet transmits into the access network
What is important about the coaxial cable physical media?
two concentric copper fibres
bidirectional
What is important about the fiber optic cable physical media?
Low error rate
high speed operation
