Improving End-to-End Performance of TCP Over mobile Internetworks

Raj Yavatkar and Namrata Bhagawat, U. of Kentucky

One-line summary: Split the TCP connection by giving the client a (new, custom) session-layer protocol on top of TCP, but accessed using the TCP API (sockets etc).

Overview/Main Points

A problem in wireless: MTU sizes smaller than for wired network, so packets traversing wired network are smaller than they need to be
Want to maintain compatibility/transparency to existing apps and wired infrastructure
Approach: Split TCP by using MHP, a session layer protocol understood at MSR and MH (which has modified socket library that connects using session protocol when application requests TCP)
MHP is a reliable session layer; maintain state across handoffs
Testbed: Desktop WSšs "simulating" wireless (lossy, small MTU, bursty errors); test program: big FTP

Relevance

Differs from I-TCP primarily in that I-TCP addresses mobility but not the inherent problems of wireless links.

Flaws

MH-to-MH is then 3 separate connections!
MTU argument is flimsy; any router in wired Internet could also fragment packets. They donšt discuss why they think this is not relevant.
Complexity of maintaining hard state across HOšs
Test program pretty specific

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