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Monthly Archives: September 2010
Summary of Lecture on Wed Sep 29
We discussed pipelining (sliding window) protocols To increase channel utilization, we have to allow the sender to transmit many packets before they are acknowledged: the pipelining mechanism. Go-back-N and selective repeat are two basic pipelining protocols. Go-back-N is simpler, but Selective Repeat … Continue reading
Summary of lecture on Mon Sep 27
We discussed briefly the Internet checksum algorithm. For more details, you can check out RFC 1071, and some performance enhancement recommendations in RFC 1141 and RFC 1624. Computing the checksum efficiently is extremely important because every single packet is sum-checked … Continue reading
Recitation Week 3
Remember that you can use either the robust read functions throughout or just the readn – do NOT mix them. The robust versions are in the robust_io.c in the MT project, the standard readn is available in network_util.c, which is … Continue reading
Primitive version of Skynet?
When discussing SMTP, I briefly mentioned that botnets are a major headache and are the main culprit in causing so many spams. Skynet is the antagonist in the Terminator. In the past few months, security researchers have been talking about … Continue reading
Summary of lecture on Fri Sep 24
We finished discussing P2P protocols and started talking about the transport layer and the principles of reliable data transfer. Another P2P-type of applications we discussed was Distributed Hash Tables (DHT). A DHT, like a normal hash table, allows for storing … Continue reading
Summary of lecture on Wed Sep 22
We continued with P2P applications. In particular, Gnutella and BitTorrent were discussed in some details. There was a question about the unchoking behavior of seeders and how that resolves the free-rider problem. Here’s the part of the official BitTorrent protocol … Continue reading
Posted in Lectures
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My Chatty implementation binaries released
You can find them here. Remember to reload your browser. Any question about the behavior of the program should be posted as comments to this post. Please use these binaries to test your implementation with. Now that you know what … Continue reading
Summary of lecture on Mon Sep 20
We briefly talked about SMTP. The gist of it is really simple. For Alice to send an email to Bob, she uses SMTP/ESMTP to submit the email to a local (outgoing) mail server. Mail servers use MX records (gotten from … Continue reading
On getting the IP & name of a machine for chatty
To implement the info command for chatty, you will have to get the IP and name of the machine which chatty is running on. In general, this information is ambiguous because — as we have discussed — a machine may … Continue reading
Posted in Project 1
Tagged connect, gethostbyname, gethostname, getsockname, Projects, udp
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Lecture 8 uploaded
It’s on P2P, in pdf. Find it here.
