[e2e] Lost Layer?

Detlef Bosau detlef.bosau at web.de
Tue Feb 11 14:40:18 PST 2014


In a sense, the situation is similar to the isarithmic approach back in
1972.

Following this approach, a network is congestion free when the amount of
data in the network is limited by a certain maximum - call it CWND.

This approach was not generally adopted because the same amount of data
in the net could mean an underload situation or an overload situation,
depending on where the data actually resides. The end to end congestion
window in TCP suffers from exactly the same weakness.
The same amount of data which means underload on a 2000 kilometres fibre
line with TBit/s throughput will mean overload on a BNC cable of 10
metres length used for a shared Ethernet connection.

Basically, the end to end CWND is the isarithmic approach applied to an
end to end path through a network.

The more an Internet path resemled a "line switched path", which may
have been through in the early 80s when the Internet was build on the
same physic as the ARPAnet, this analogy will hold. The more the
Internet becomes heterogeneous, data rates along a path may vary on a
scale of 8 orders of magnitude or more, wireless links may render the
classical idea of links being "on" or "off" useless, the more this
analogy may become questionable.

Detlef

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