Computer Networking Assignment
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,Problems
1 TCP over Long Fat Networks (LFNs)
The goal of this problem is to familiarize yourself with the basics of
ns while examining the inter-action between Teri. LFNs and
routers. LFNs (pronounced "elephants") are networks with "fat
pipes," where the bandwidth-delay products are large. Two about-
to-disappear .tom's AlphaWidgets.com and BetaGadgets.com have
decided to connect their networks to divert each others' dwindling
set of customers to each other in the hope that this will save
them. They hope to stick a single router between their two
networks, and they have given Ben Bitdiddle, who is taking 6.829,
the task of configuring the router. Ben decides to perform a few
simulations studies in ns in order to understand better the details
of configuring the router.
1. Ben begins his study by examining the dynamics of a simple
TCP connection from AlphaW-idgets to BetaGadgets over his
router. Download Ben's script from ht tp : //nms lcs . mit .
edu/6.829/ps/ps2/LFN .t cl and examine it.
(a) What is the round-trip time (RTT) and bandwidth of the links
that Ben is simulating? How fast is his router? What kind of
queueing discipline does his router use?
(b) Run the script and plot the evolution of the sender's TCP
window over time. Identify where TCP slow-start ends and
where congestion-avoidance begins.
,2. Ben looks at a map of BetaGadgets' network and notices that
some of BetaGadgets' traffic travels over satellite links. He
estimates that the average RTT for a connection between
AlphaWidgets and BetaGadgets over satellite is 500 ms.
(a) Reconfigure Ben's script so that the RTT for the connection is
500ms and repeat parts (a) and (b) above.' (Note: You will need
to increase the length of the simulation in order to see TCP
enter the steady state.)
(b) Without looking at the simulation results, tell us how big the
average congestion window would need be to allow a single TCP of
fully utilizing the bottleneck link.
(c) From your plot in 2-(a), what is the maximum value of TCP's
congestion window size in the steady state? What is peculiar about
the evolution of TCP's congestion window over time in this case
(use part (a))?
, 3. Ben figures that the problem with his satellite simulation has
something to do with the size of the queue at the router; packets
seem to be getting dropped as the T CP connection bursts traffic in
slow start.
(a) Plot the evolution of the queue over time as well along with the
evolution of the sender's congestion window.
Help Services
For any help regarding Computer Network Assignment Help
Visit :- https://www.computernetworkassignmenthelp.com/,
Email :- or
Call us at :- +1 678 648 4277
,Problems
1 TCP over Long Fat Networks (LFNs)
The goal of this problem is to familiarize yourself with the basics of
ns while examining the inter-action between Teri. LFNs and
routers. LFNs (pronounced "elephants") are networks with "fat
pipes," where the bandwidth-delay products are large. Two about-
to-disappear .tom's AlphaWidgets.com and BetaGadgets.com have
decided to connect their networks to divert each others' dwindling
set of customers to each other in the hope that this will save
them. They hope to stick a single router between their two
networks, and they have given Ben Bitdiddle, who is taking 6.829,
the task of configuring the router. Ben decides to perform a few
simulations studies in ns in order to understand better the details
of configuring the router.
1. Ben begins his study by examining the dynamics of a simple
TCP connection from AlphaW-idgets to BetaGadgets over his
router. Download Ben's script from ht tp : //nms lcs . mit .
edu/6.829/ps/ps2/LFN .t cl and examine it.
(a) What is the round-trip time (RTT) and bandwidth of the links
that Ben is simulating? How fast is his router? What kind of
queueing discipline does his router use?
(b) Run the script and plot the evolution of the sender's TCP
window over time. Identify where TCP slow-start ends and
where congestion-avoidance begins.
,2. Ben looks at a map of BetaGadgets' network and notices that
some of BetaGadgets' traffic travels over satellite links. He
estimates that the average RTT for a connection between
AlphaWidgets and BetaGadgets over satellite is 500 ms.
(a) Reconfigure Ben's script so that the RTT for the connection is
500ms and repeat parts (a) and (b) above.' (Note: You will need
to increase the length of the simulation in order to see TCP
enter the steady state.)
(b) Without looking at the simulation results, tell us how big the
average congestion window would need be to allow a single TCP of
fully utilizing the bottleneck link.
(c) From your plot in 2-(a), what is the maximum value of TCP's
congestion window size in the steady state? What is peculiar about
the evolution of TCP's congestion window over time in this case
(use part (a))?
, 3. Ben figures that the problem with his satellite simulation has
something to do with the size of the queue at the router; packets
seem to be getting dropped as the T CP connection bursts traffic in
slow start.
(a) Plot the evolution of the queue over time as well along with the
evolution of the sender's congestion window.
