Tuesday, April 7, 2009

Happy Birthday to Kahn's Algorithm

This evening I was giving a lecture on TCP timeout and retransmission. We looked at different situations where the client does not get an ack or response to its syn request and the students got to see how the RTO algorithm works in real life, I think they enjoyed the lecture. We also looked at a RFC 793 which covers Transmission Control Protocol and looked at how Microsoft made some changes to their implementation of TCP in 2003 Server so that they could understand how actual implementations can differ from the RFCs.

The last thing that we did was look at the email that Phil Karn sent on A New TCP Retransmission Algorithm. We talked about Khan's research and how is statements on packet radio applied to IEEE802.11 networks, and finally we loked at his famous algorithm and I commented about how he got his research data and tested his algorithm as well as the quality of writing in his informal email as I was looking at it I saw that the message was sent on Tuesday, 7th April 1987 at 20:59. I had shared this with my class on Tuesday, 7th April 2009 at 20:44. Twenty two years to the exact day of the week! Of course this made me very happy and I told the class that if we all had sodas I would have proposed a toast to Phil Kahn.

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