DiskSims 1.0 Beta

Release of DiskSims 1.0 Beta with source code. Added disk properties dialog box. Hard disk internal geometry can be defined more accurately. The project is now posted in sourceforge here.

I know this release may be a bit of a surprise, since I was working on Hegons and (according to my last post) I should be busy with the SPECTS conference. Unfortunately I couldn’t get a vacation/funding for it 🙁 So cancelled my visit. well, At least the paper is published.


spects2007_promo-1A paper I have written with my friend Fadi and Dr.Sami on wireless sensor networks has been accepted to be released in SPECTS 2007 conference in San Diego. I’m looking forward to going there.  The paper named “Impact of Dynamic Channel Assignment on Blocking Probability in Ad Hoc Wireless Sensor Networks” is my first published paper. Although I don’t consider it the best work I’ve done yet. I’m currently working on a paper on optical networks hopefully to be published soon.

Hegons v0.3

Hegons Beta version 0.3 released.

– New node type 4, “Multi-hop Partial Grooming” nodes. As far as I know, This makes Hegons the first simulator that explicitly supports these types of nodes. A Partial Grooming node has 2 cores connected to together, a W-fabric and a G-fabric. A W-fabric is an all optical core just like a non-grooming node. a G-fabric is a wavelength converting full grooming core. Both cores can receive incoming and outgoing calls. Optionally, the W-fabric can be wavelength converting.
– A partial grooming node can have MULTIPLE G-fabrics. This is a new concept that has never been discussed in the literature.
– The RWA method chosen will be applied internally in the nodes between W and G fabrics as well as externally. In other words, the cores are treated as normal nodes when doing RWA. This has been the case also when doing internal RWA for Single-hop grooming nodes. i.e. between the cores and the grooming ports.
– Added -px and -pn options for controlling max/min number of times G-fabric switchings are done per call.
– Few other minor fixes and changes.

Hegons v0.2

Hegons Beta version 0.2 released. Added -ll and -ml options for “Least Loaded Routing (LLR)” and “Most Loaded Routing (MLR)”. For the grooming case, The simulator assumes the path with the least (or most) number of time slots used to be the least (or most) loaded path. However, those 2 methods are still not well defined for the grooming case in the literature.


HEGONS Beta version 0.1 released. A HEterogeneous Grooming Optical Network Simulator. Supporting mixed routing & wavelength assignment algorithms and optional wavelength conversions capability on each node. Unlike many other simulators, the goal in developing Hegons is NOT to simulate the OSI model layers as they are. Such simulators mimic the behavior of say TCP/IP or GMPLS in order to provide a virtual platform for developers, learners and testers. Hegons on the other hand, aims at one thing and only one thing: The evaluation of different dynamic Routing and Wavelength Assignment (RWA) algorithms in WDM optical networks in terms of several measures such as: call blocking probability, Fairness (Variance in blocking probability), call setup time, etc. Thus Hegons is not bound to any specific protocol unless it is related to RWA algorithms, which leads to a great deal of source code reduction and optimization being possible. This fact makes Hegons work much faster in producing usable results that can help researchers in the field. The following is a list of the main features:

  • Supports practically unlimited number of nodes in a network. (2 billion)
  • Supports practically unlimited number of wavelengths per link. (2 billion)
  • Typically, can simulate more than 18 million calls per minute on a 2Ghz PC.
  • Currently Supports 3 types of nodes (OXCs).

1. Non Grooming node.
2. Single-Hop Grooming node.
3. Multi-Hop Full Grooming node.

  • Each node can optionally be a wavelength converter node.
  • 4 wavelength assignments (WA) algorithms:
    1. First Fit (FF)
    2. Random (R)
    3. Most Used (MU)
    4. Least Used (LU)
  • Fixed Alternate Routing (FAR) is supported with 4 different ordering algorithms: FF, R, MU, LU
  • Shortest Path Routing (SPR) can be supported by using -mp:1 option.
  • Call arrivals follow the poisson distribution.
  • Can run multiple batches (separate simulation runs) automatically and find the average results of all batches.
  • Three different methods to calculate the blocking probability. Can be controlled by modifying the BP_METHOD compiler directive.
  • Average number of attempts for each call can be limited using the -at option.
  • Maximum and minimum path length can be controlled.
  • Maximum number of paths generated for each source to destination pair can be controlled
  • Network description can be loaded from a file or can be feeded interactively by the user.
  • Results can be saved to CSV (Comma Separated Values) files for easy batch running. CSV files can be then viewed in Excel and charts can be generated instantly.

Multi-hop Partial grooming nodes (OXCs) are planed for future versions. Least Loaded Routing is also coming soon.

Limitations and assumptions:

  • The simulator supports only single fibre links.
  • All wavelengths on all fibres can support the same maximum number of groomable time slots.

So far, the highest priority in the development of Hegons has been performance in terms of speed. I tried to optimized the code to make it run as fast a possible. Since there is always a tradeoff between speed and memory usage, Hegons can indeed consume a considerable amount of RAM. However, Hegons will not be memory hungry unless the network is really large (More than 100 nodes) with allot of links. Memory requirements grow exponentially with large networks as the simulator stores shortest paths from each source to each destination nodes.

Finally, The project is still under development. I’m always willing to hear from interested people. Your feedback is welcome.

CCNA Certified!!

Just got my CCNA (Cisco Certified Network Associate) certification today. After more than 2 months of studying I managed to pass the final ICND exam after doing the INTRO exam a month ago. More info about CCNA can be found here http://cisco.netacad.net. Also, a great forum for CCNA learners is http://www.firewall.cx.

DiskSims development is currently on pause, until I finish a currently worked on paper on optical networks. Also, I’m working on a new simulator, “Hegons” a Heterogeneous Grooming Optical Network Simulator. Ya ya ya, I know… you have no idea of what I’m talking about. Explanations are coming later on.

Exhibition at KU

Last Wednesday, DiskSims has been presented in an exhibition for graduate students projects held in Kuwait University. A number of different projects from different colleges have been presented too. The picture shows me (at the left) presenting DiskSims and our new algorithms to the minister of information Mr. Anas Al-rishaid (the man holding the paper).

I had little time to prepare for the event. I just finished the poster on Tuesday. And at Wednesday morning I came in a rush to my table at the exhibition to find that all other presenters had DATA SHOWS (Projecters) while I didn’t. I was never told I should. How careless am I. I called every one I new who could help, but no gain. Then the minister came and he was passing on the tables one by one. Man that was embarrassing. I was nervous. But thank god, a person I new there told me about an unused data show there. I was like pfeww… :). I rushed to connect it to my laptop before the minister approaches me. Since that moment every thing went so fine.

Allot of the people who passed by stopped and took a look. Some were asking questions. Some took our brochure. Overall, it was nice. The event was broadcast on national TV at night. Unfortunately……. errrrr or fortunately, I didn’t appear.


Release of DiskSims beta version. A disk-scheduling simulator that I have been developing as my masters degree project.

This is a skimmed beta version of the full simulator. Many features are disabled that are part of our two newly proposed scheduling algorithms (SLOOK and BO-PATH). Some other features are also still under implementation. The basic simulation and automated chart printing for common scheduling algorithms are fully working.

The full version of DiskSims will be released as soon as we (me and Dr.Ayed Salman) publish the new two algorithms on paper. The full version will include the source code and will probably be released under the GNU General Public License.

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