[e2e] Switched Ethernet is Not an End-to-End System; was Protocols breaking the end-to-end argument

Jon Crowcroft Jon.Crowcroft at cl.cam.ac.uk
Sun Nov 1 02:10:52 PST 2009

There definitely are lessons 
in the evolution from 
end-mediated contention to 
switch-mediated access
in ethernet-land.

The oft-perceived analogy
of the whole internet as a big ethernet,
a huge shared resource 
with contention mainly mediated
by end systems, is alluring.

So the move to 
net/switch-centric resource allocation/control
in the local, 
might suggest some similar move
in the wide area...
until you actually think about the
heterogeneity in the
topology, in capacity and in latency,
of the system - 

Plenty of enterprise nets and small ISPs
(e.g. UK size) can consider
a carrier-grade switched ether
control philosophy (e.g. 
esp. to replace
complicated MPLS setups:)
but it doesn't subsume/replace e2e
resource sharing - 

It doesn't address 
multihomeing, multipath, mobility or multicast
in any useful way either...it doesn't
speak to swarms and CDNs much either.

There were other lan technologies
which didn't have built in collapse
as part of the media-sharing protocols
so the lesson wasn't as widely
necessary as the e2e monoculture
pretends (people who built 
token and slotted rings
had other views of the world 

On the other hand, it would be instructive
to see how many end&edge systems are now on
wireless ethernet and to see if the balance has
swung back once again in "favour" of 
shared media/contention. 



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