Dear all
I'm working on a tor research project and am having difficulty understanding the SENDME cells. The tor spec acknowledges that it isn't particularly clear so I would welcome some clarification please.
The spec says that all nodes in a circuit maintain a send and receive window, and that this window is decremented on each RELAY_DATA and incremented on each SENDME. Cells that are neither of these do not affect the window size. The problem I have understanding is, that only edge nodes will know whether a cell is a RELAY_DATA, the intermediate nodes only know that its a RELAY but not what type. So, if only RELAY_DATA decrements the window size, and intermediate nodes cannot spot these, what point is there in intermediate nodes having a window?
Any help greatly appreciated.
Gareth
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Dr Gareth Owen
Senior Lecturer
School of Computing, University of Portsmouth