Re: [tipc-discussion] Link level packet loss

[Erik H. <eri...@er...>]

> What i have yet to discover is _why_ this occurs, packets should always
> be put on the deferred queue if they are not 'next_in_no', and the
> deferred packets should only be replayed back on the receive loop when
> we have all previous packets..
>

When the link supervision timer kicks in, we will flush ongoing 
reassemblies if they have not successfully received a fragment within 
[link tol]*4 seconds.

This will then lead to the problem explained in the previous mail, since 
we obviously have dropped the buffer.

I think this is a fault from which we cannot recover nicely, since the 
dropped buffer is built up of packets already acked on the link.

So i'm suggesting that we reset the link immediately and print a helpful 
error message when this occurs.
The problem will be mitigated by increasing link window size and/or 
tolerance levels.

Jon: do you the remember the reasoning for flushing stale reassembly 
buffers every fourth link timeout, if we have not received a fragment 
for this ongoing reassembly yet?
http://lxr.free-electrons.com/source/net/tipc/link.c#L2584


//E