More reading

I'm reading a few more papers these days. One of them is a new traffic engineering approach called COPE, common case optimization with penalty envelop. Another one explores the possibility of doing traffic engineering together with congestion control. Yet another one is about MIRO multipath interdomain routing. Other avenues include virtual network overlays such as VINI. I'll post URLs later on.

Handed over phase II

Yesterday we handed over the results of the phase II simulations of the GELS project to Siemens, Germany. The conference call lasted about 50 minutes. Now we will explore options to further this work.

Paper submitted

This morning, after toiling for weeks on end, we finally submitted a paper to Icc 2007. The paper is title "A simulation study of GELS for Ethernet over WAN." Let's see how the reviews go. It wouldnt be evaluated till January next year.

Corrected

We had very high standard deviations in the convergence time of RSTP in our topologies. Investigating the reasons, we found that links going from Blocking to Forwarding state with a blocked state on the others side were taking two hello time worth in switching state. That doesnt matter to us, because those links dont carry any stations originating traffic (point to point ethernet links) and do not form part of the spanning tree. The spanning tree itself converges upon link failure within a second in all of our failure scenarios. I had to make adjustments to the shell scrip to summarize the results and we are running the simulations yet again.

Bridgesim bug

Running the 50 node topology simulations for single link failures, we came across some situations where the simulator would say, cannot find link between node x and node y, while the simulator itself was showing that link in its log output on the console, right there. Investigating this message, I found that the simulator was checking for NUMBER_OF_PORTS which was #defined to be 40, whereas the port numbers were running all the way to 50. So, I went ahead and changed that in bitmap.h and rebuilt bridgesim. That solved the problem.

Update

So, my advisor is doing this research project with Siemens, which I joined in. The project concerns carrying LAN traffic transparently across a WAN. Not like using VPNs or something. One approach is to use MPLS and carry Ehternet traffic inside MPLS packets. Another approach is to use GMPLS Controlled Ethernet Lable Switching (GELS). Yet another approach is to use Ethernet as is in the core using point to point Ethernet links between the routers.
The problem with the third approach is that it runs STP, which prunes the partially or fully meshed topology, which reduces the available bandwidth and hence less traffic demands can be met. Siemens are interested in GELS (By the way, it is still in the IETF draft stages). But we wanted to quantify this loss in bandwidth incurred by STP, which obviously wouldnt be incurred by GELS since it doesnt prune the topology and will bring other benefits as well.
So, in the first phase of the project, which is already complete, we compared the link utilization, traffic demand acceptance characteristics of STP and GELS and quantified it based on traffic matrices and topologies provided to us by Siemens. We used the TOTEM simulator to do this. We added our own protocol variant of CSPF to the simulator.
The need for the new protocol was to get a common ground for comparison. The problem is that with GELS, CSPF, we are setting up LSPs based on traffic demands, whereas with STP, everything is contention based and there is no concept of LSP. So, we implemented a variant of CSPF that accepts and sets up an LSP if required bandwidth is available and if requested bandwidth for the LSP isnt available, it allocates the highest possible fraction of the requested bandwidth, just as (at some leve), one would get with STP. I'll see if I can upload the code some time.
Now, in the second phase, we are evaluating failure scenarios to see how the two protocols compare in terms of recovery from failures. We are simulating single link failure scenarios for the given topologies on bridgesim. I have modified a C++ program developed by my fellow research student Atif Nazir and developed a shell script to simulate all possible single link failure scenarios with every node in the network selected as root bridge one by one and extracting the convergence time from the simulator's output log file. These results are then put into the gnumeric spereadsheet program and computations are done on the results.
Each single node failure scenario is taking about 50 seconds to run on the Virtual PC environment in which I set up Red Hat Linux 9.0 and there are a total of 82 links in the topology with 50 root nodes, so the entire simulations set will take about 57 hours to complete. Fun stuff, huh? Good for us I wrote the code to automate all this stuff, so that all we need to do is to ensure that the code is doing what we want to do, which I have already done in testing, and to copy and paste the results.

Long absence

I am back after a long absence. It isnt that I wasnt doing anything, but it's just that I was doing too much to be able to report anything here. I was initially reading stuff on running MPLS over OBS for a high speed Internet core and I found some work on it. Presently, I am taking a course "CS 678 Topics in Internet Research" in which we are reading a research paper for every class, which makes for two papers a week. We read the papers on our own, bring a brief summary to the class, where we discuss the paper.
There is also an individual term project for which two other students will be consultants and monitor the progress. For that, we have to come up with a research idea. I have found a few papers on Internet Traffic Statistics and have deposited the proposal to devise a scheme for doing accurate traffic statistics on core routers. We're talking about Tier 2/3 ISPs. I am presently reading a paper about "Inverting sampled traffic."
I made a presentation about it yesterday. The idea is similar to survey sampling. You gather a subset of the data and project information about the whole. I'll give links to documents as we go along.