(paper)
Data centers try to route their traffic through middleboxes (firewalls, load balancers, NATs, etc). They typically do this by putting them in-line on the network topology and trying to ensure there are no other paths. Sometimes some network traffic doesn't need to go through a particular box but it will anyway because that's how they've set up the topology. This paper proposes a L2 way to accomplish this better; they call it "the policy-aware switching layer", aka PLayer. The properties they want are correctness (can't circumvent), flexibility, and efficiency. pswitches classify traffic and redirect it to the appropriate middlebox. Middleboxes do not need to be modified, but switches would need to be changed. There is a central policy server that sends policies to all the pswitches so they know how to classify and direct traffic.
They implemented prototype pswitches using Click, and then "validated" its functionality on the DETER testbed. They make the disclaimer about their work being a prototype which of course tips you off that their performance is bad: 40% of normal throughput with 2x the latency. Owch!!!
They then provide a formal analysis that I do not buy at all. I personally think that a formal analysis of a system like this is BS. They are just rephrasing what they have said earlier in the paper with subscripts.
Interesting paper but honestly they went into too much detail and lost my attention in places. This might be because this is a tech report. In a few places it seemed like they were unnecessarily belaboring obvious points that I didn't need convincing about.
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It is true that this paper is detailed ... actually it was a shortened version that appeared in the conference. Some of the details are there to prove feasibility of the approach. You may find it interesting to know that they submitted this paper several times before it got accepted, mainly because the reviewers kept raising objections about implementation concerns.
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