Monday, September 22, 2008

Parallelism in the router, i.e. switched backplanes

After reading today's paper on the gigabit switched router, I realized that I should have read it before reading today's other paper because this paper is more approachable and didn't assume an intimacy with internet routing technology. Figure 2 even uses a picture to explain the evolution of high performance routing! What is more, I now know what they were talking about in the other paper when they spoke of router scheduling and VOQ.

They are engineering a 16 port x 2.4Gbps per port = 38.4Gbps

Shared backplanes could (at the time of writing) support 20Gbps, not enough.

They present iSLIP, a simple effective router scheduling algorithm.

While iSLIP allows for high throughput (100%) of the router's backplane, it does not address delays which might be problematic for latency sensitive applications. Thus, they introduce the intuitive mechanisms of prioritization and speedup (get all packets to the output port as quickly as possible so they can be scheduled).

Random notes:
  • average internet packet is 250 bytes
Keep this paper on the list! It is very informative for those of us who don't know router architecture coming into the course (which I imagine might be a non-trivial portion of us).

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