Data Communications Exam 2
What are the four components of delay? - ANS-Transmission, Propagation, Processing, and
Queueing
Where are queues likely to form? - ANS-Processor or Link
What is the minimum packet size? What is this packet size usually used for? - ANS-Minimum
packet size of 40 bytes, typically used for multimedia.
Maximum Packet Size - ANS-1500 bytes (Web/file xfer)
Average Packet Size - ANS-300 bytes (typical data)
Transmission delay is... - ANS-Time it takes to signal all bits on link
Propagation delay is... - ANS-Time it takes for signal to travel
Transmission Delay = - ANS-8B/R where B = bytes and R is transmission speed
Number of packets in pps for transmition - ANS-1/(Transmission Delay)
How do you calculate the "Burstiness" of a network - ANS-Peak Rate / AverageRate
The service capacity (μ) is... - ANS-μ is the smaller of the processor or output port capacity
and is measured in pps (packets per second)
μ^(-1) defines what? - ANS-The service time per packet
How is N defined in regards to utilization/capacity? - ANS-N = ρ/(1-ρ)
Propagation Delay - ANS-Distance/(2*10^8)
Source Activity Probability = - ANS-1/Burstiness = AverageRate/PeakRate
w (wait time) - ANS-(1/μ)(ρ/(1-ρ))
Total Delay - ANS-Total delay is the sum of the processing, propagation, queue, and
transmission delay
Probability that there are a certain amount of packets in queue - ANS-ρ^B
, where ρ = utilization
where B = buffer size
Memory Size = - ANS-B*Buffersize
where B is the number of Bytes
What is the job of the network layer - ANS-Deliver data from the source to the destination
How are IP networks segmented - ANS-IP Networks are divided into networks, subnets, and
hosts
Subnets - ANS-analogous to LANs
-each LAN is typically a subnet
-Each connected broadcast domain is a subnet
How many bits are in an IP address? - ANS--comprised of 32 bits
CIDR - ANS-Classless InterDomain Routing
-address format: a.b.c.d/x, where x is # of bits in subnet portion of address
-subnet portion of the address is an arbitrary length
Global Addresses - ANS-Address space that all networks can share - assigned for global use
Local Address - ANS-Address space that is really only meaningful to the network that is using
the space
Inside Addresses - ANS-Address assigned to device inside your network
Outside Addresses - ANS-Address assigned to device on the outside
Port Address Translation - ANS-NAT with the addition of swapping port numbers
Routers that forward IP Packets - ANS-Routers that forward IP Packets are stateless
-they forward to the next router and forget about it
-They trust that the next router will continue the delivery process
IPv4 - ANS--IPv4 is packet based
-it is a connetionless protocol (best effort)
How packets get delivered - ANS-1.Each host knows the next hop or a default hop
2.At each host, including the source node, the subnet is compared to a list of subnets. If that
subnet is attached the packet is directly delivered (see ARP)
What are the four components of delay? - ANS-Transmission, Propagation, Processing, and
Queueing
Where are queues likely to form? - ANS-Processor or Link
What is the minimum packet size? What is this packet size usually used for? - ANS-Minimum
packet size of 40 bytes, typically used for multimedia.
Maximum Packet Size - ANS-1500 bytes (Web/file xfer)
Average Packet Size - ANS-300 bytes (typical data)
Transmission delay is... - ANS-Time it takes to signal all bits on link
Propagation delay is... - ANS-Time it takes for signal to travel
Transmission Delay = - ANS-8B/R where B = bytes and R is transmission speed
Number of packets in pps for transmition - ANS-1/(Transmission Delay)
How do you calculate the "Burstiness" of a network - ANS-Peak Rate / AverageRate
The service capacity (μ) is... - ANS-μ is the smaller of the processor or output port capacity
and is measured in pps (packets per second)
μ^(-1) defines what? - ANS-The service time per packet
How is N defined in regards to utilization/capacity? - ANS-N = ρ/(1-ρ)
Propagation Delay - ANS-Distance/(2*10^8)
Source Activity Probability = - ANS-1/Burstiness = AverageRate/PeakRate
w (wait time) - ANS-(1/μ)(ρ/(1-ρ))
Total Delay - ANS-Total delay is the sum of the processing, propagation, queue, and
transmission delay
Probability that there are a certain amount of packets in queue - ANS-ρ^B
, where ρ = utilization
where B = buffer size
Memory Size = - ANS-B*Buffersize
where B is the number of Bytes
What is the job of the network layer - ANS-Deliver data from the source to the destination
How are IP networks segmented - ANS-IP Networks are divided into networks, subnets, and
hosts
Subnets - ANS-analogous to LANs
-each LAN is typically a subnet
-Each connected broadcast domain is a subnet
How many bits are in an IP address? - ANS--comprised of 32 bits
CIDR - ANS-Classless InterDomain Routing
-address format: a.b.c.d/x, where x is # of bits in subnet portion of address
-subnet portion of the address is an arbitrary length
Global Addresses - ANS-Address space that all networks can share - assigned for global use
Local Address - ANS-Address space that is really only meaningful to the network that is using
the space
Inside Addresses - ANS-Address assigned to device inside your network
Outside Addresses - ANS-Address assigned to device on the outside
Port Address Translation - ANS-NAT with the addition of swapping port numbers
Routers that forward IP Packets - ANS-Routers that forward IP Packets are stateless
-they forward to the next router and forget about it
-They trust that the next router will continue the delivery process
IPv4 - ANS--IPv4 is packet based
-it is a connetionless protocol (best effort)
How packets get delivered - ANS-1.Each host knows the next hop or a default hop
2.At each host, including the source node, the subnet is compared to a list of subnets. If that
subnet is attached the packet is directly delivered (see ARP)
