I am currently researching on SDN in mobile networks (LTE). for that i am looking for a simulator, need advise.
I have gone through NS3 and it appears as it supports Openflow Switches, but couldn't find documentation for that purpose. Need help in simulating SDN network in LTE. any suggestion/advise would be highly appreciated.
Thanks,
Shahzoob
NS-3 has a module called ofsoftswitch13 which might be quite helpful in your case. It implements controller entity as well as OF 13 protocol.
I did an undergraduate thesis on this topic and used Mininet and Ns-3 together using this project. We primarily did validity testing on this platform to determine it's accuracy and limitations (especially at scale). The wireless model is very good until a very clear performance degradation when the CPU usage reaches (100/n)% - where n is the number of available cores on the machine (for a single threaded implementation).
Related
Can someone explain to me what is CAN BUS protocol stack? Is it CAN BUS+ higher layers, like CANopen with 7 layers or something else, and can someone explain how can I use CAN stack, how I connect it with CAN bus, and why I need it?
Thank you
Yes it is CAN hardware with higher layer protocols, such as CANopen, J1939 or DeviceNet.
In terms of the "OSI model", it only really makes sense to speak of layers 1-3 and 7, where CAN is layers 1 and 2 and a protocol like CANopen roughly provides layers 3 and 7. Roughly, since CAN-open also comes with hardware specifications such as baudrate, sync point & stub length recommendations.
What's known as a "protocol stack" is really just a library with a platform-independent API, usually delivered with hardware-specific drivers. If the vendor claims that they support a particular MCU, then it usually means that you get the drivers from the vendor.
So basically you buy this pre-made library and integrate your program with it, then get standardized protocol behavior on the CAN bus, necessary to communicate with other nodes implementing the same protocol. Writing such a library yourself is no small task, particularly not for CANopen which is a big standard, where you are probably just going to use some 10% of the available functionality.
I am currently setting up a testing SDN environment, so I am familiar with the sdn concept (separating the Control Plane from the Data Plane of a Switch).
Within my research I was often reading about VXLAN when there was talking of SDN.
Now I am a bit confused, because I understand VXLAN as a Tunneling Protocol and I dont know how this would be related to my idea of SDN.
Another question I would like to ask is: Would it be possible to Connect a Switch over several non-sdn Networks to a existing SDN Topology/ SDN Controller with the VXLAN Technology?
Thank you in advance
you should differenciate between SDN as a concept and VXLAN as a tunneling protocol.
The later used to tag packets and hence you can do some kind of seperation in layer-2. This technique helps with network slicing and have been used in flowvisor.
Forwarding traffic through non SDN network have been studied in many works. I suggest you to read the last one
Magneto: Unified Fine-grained Path Control in Legacy and OpenFlow Hybrid Networks
Good luck
I am a ME undergrad and am designing an implant device that requires programming knowledge. I honestly have no idea how to get started and am looking for advice. Basically what I need is a way to control a stepper motor. Stepper motor's use steps (pulses) to rotate the gear head. Now this motor I'm using needs 20 steps to revolve once. I need to be able to control the # of steps I want in a day per say. The motor I'm purchasing comes with an encoder which I'm guessing connects to the circuit board. Now what I want to do is have an external control (like a remote control for a toy)that can set these rates. I don't know anything about radio transmitters, or how to program the circuit board to do this for me. Any help would be appreciated, or books I can look into, websites, or tutorials. Thanks.
There are many ways of solving this problem, but it is more of a systems engineering question than a programming question; until you know what the system looks like, there is no way of determining what parts will be implemented in software. More details would be required to provide a specific answer.
For example what are the security/safety considerations?
What wireless technology do you need to use? e.g. RF or IR, if RF then licensing may be an issue, and that may vary from country to country. You could use BlueTooth, ZigBee, or even WiFi, but these technologies are probably more expensive and complex than necessary for such a simple application. If IR then is immunity from interference from TV remotes or PC IrDA ports or similar required?
If the commands/signals from the remote are complex you will probably need both the remote and the motor driver to incorporate a micro-controller and software. On the other hand if you just need increase/decrease functions then it would be entirely possible to implement the remote functionality you describe without any processing at all (depending on teh communication technology you choose).
What is the motor encoder for? Stepper motors do not normally need an encoder since the controller can simply count steps executed in either direction to determine position. Is the encoder incremental or absolute? If it is incremental, then it is certainly not needed; if it is absolute than it may be useful if you need to know the exact position of the motor on power-up without having to perform an initialisation or requiring end-stop switches.
You mentioned a "circuit board"; what hardware do you already have? What does it do? Do you have documentation for it? If it is commercially available, can you provide a link so we can see the documentation?
As you can see you have more system-level design issues to solve before you even consider software implementation, so the question is not yet ready to be answered here on SO. I suggest you seek out your university's EE department and team-up with someone with electronics expertise do design a complete system, then consider the software aspects.
Well worth taking a look at the Microchip site:
http://www.microchip.com/forums/f170.aspx
They produce microcontrollers that can be programmed to do exactly what you require (and a lot more).
I have been tasked to write a device driver for an embedded device which will communicate with the micro controller via the SPI interface. Eventually, the USB interface will be used to download updated code externally and used during the verification phase.
My question is, does anyone know of a good reference design or documentation or online tutorial which covers the implementation/design of the USB protocol stack/device driver within an embedded system? I am just starting out and reading through the 650 page USB v2.0 spec is a little daunting at the moment.
Just as a FYI, the micro controller that I am using is a Freescale 9S12.
Mark
Based upon goldenmean's (-AD) comments I wanted to add the following info:
1) The embedded device uses a custom executive and makes no use of a COTS or RTOS.
2) The device will use interrupts to indicate data is ready to be retrieved from the device.
3) I have read through some of the docs regarding Linux, but since I am not at all familiar with Linux it isn't very helpful at the moment (though I am hoping it will be very quickly).
4) The design approach, for now at least, it to write a device driver for the USB device then a USB protocol layer (I/O) would reside on top of the device driver to interpret the data. I would assume this would be the best approach, though I could be wrong.
Edit - A year later
I just wanted to share a few items before they vanish from my mind in case I never work on a USB device again. I ran into a few obstacles when developing code and getting it up and running for the first.
The first problem I ran into was that when the USB device was connected to the Host (Windows in my case) was the host issues a Reset request. The USB device would reset and clear the interrupt enable flags. I didn't read the literature enough to know this was happening, thus I was never receiving the Set-Up Request Interrupt. It took me quite a while to figure this out.
The second problem I ran into was not handling the Set-Up Request for Set_Configuration properly. I was handling it, but I was not processing the request correctly in that the USB device was not sending an ACK when this Set-Up Request came in. I eventually found this out by using a hardware USB protocol analyzer.
There were other issues that I ran into, but these were the two biggest ones that took me quite a while to figure out. The other issue I had to worry about is big-endian and little-endian, Freescale 9S12 vs USB data format (Intel), respectively.
I ended up building the USB device driver similar to UART device drivers I had done in the past. I have posted the code to this at the following URL.
http://lordhog.wordpress.com/2010/12/13/usb-drive
I tend to use structures a lot, so people may not like them since they are not as portal as using #defines (e.g., MAX3420_SETUP_DATA_AVAIL_INT_REQR 0x20), but I like them since it makes the code more readable for me. If anyone has questions regarding it please feel free to e-mail and I can try to give some insight to it. The book "USB Complete: The Developer's Guide" was helpful, so long as you knew what areas to concentrate on. This was a simple application and only used low-speed USB.
While writing a device driver for any interface (USB, Parallel port, etc...) the code needed to be developed would depend upon whether there is any Operating System(OS), RTOS running on that Processor/Micro controller.
e.g. if thats going to run say WinCE - It will have its own Driver development Kit , and steps to be followed in the device driver development. Same for any other OS like Linux, symbian.
If its going to be a plain firmware code(No OS) which is going to control the processor/microcontroller, then it's a different situation altogether.
So based on either of the above situation u are in, one needs to read & understand:-
1.) The Hardware Specification of the processor/micro controller development board - Register files, ports, memory layout, etc.
2.) USB spec
3.) Couple of pointers i found quickly. Google shud be ur friend!
http://www.lrr.in.tum.de/Par/arch/usb/usbdoc/ - Linux USB device driver
http://www.microsoft.com/technet/archive/wce/support/usbce.mspx
-AD
I've used an earlier edition of USB Complete by Jan Axelson. Indeed very complete.
From the editorial review:
Now in its fourth edition, this developer's guide to the Universal Serial Bus (USB) interface covers all aspects of project development, such as hardware design, device firmware, and host application software.
I'm curious, why did you pick the 9S12? I used it at a previous job, and was not pleased.
It had lousy gcc support so we used Metrowerks
which may have been okay for C, but often generated buggy C++
had a lousy IDE with binary project files!
The 9s12 was also slow, a lot of instructions executed in 5 cycles.
Not very power efficient, either.
no barrel shifter, made operations that are common in embedded code slow
not that cheap.
About the only thing I dislike more is an 8051. I'm using an ARM CortexM3 at my current job, it's better than a 9S12 in every way (faster clock, more work done per clock, less power consumption, cheaper, good gcc support, 32-bit vs. 16-bit).
I don't know which hardware you're planning to use but assuming that's flexible, STMicro offers a line of microcontrollers with USB/SPI support and a library of C-code that can be used with their parts. -- I've used their ARM7 series micros for years with great success.
Here is an excellent site maintained by Jonathan Valvano, a professor at the University of Texas. He teaches four courses over there (three undergraduate, one graduate), all are about using a 9S12 microcontroller. His site contains all the lecture notes, lab manuals, and more importantly, starter files, that he uses for all his classes.
The website looks like it's from the 90's, but just dig around a bit and you should find everything you need.
users.ece.utexas.edu/~valvano/
Consider AVR for your next MCU project because of it's wonderful LUFA and V-USB libraries.
I'm working on a project using the Atmel V71. The processor is very powerful and among lot's of high end connectivity offered on chip is a USB engine that will do device or host modes for 480 Mhz or 48Mhz (not USB 3.0). The tools are free and come with a number of host and device USB example projects with all the USB stack code right there. It supports 10 end points and all the transfers are done via DMA so you have most of the processor horsepower available for other tasks. The Atmel USB stack works without needing an RTOS
I'd like to have an application monitor written in C# monitoring a set of Forex trading positions. It would be connected via USB to a real set of "traffic lights" sat on a desk which it would use to indicate system status. Can anybody suggest a good solution?
Normally I'd say parallel port or some other such thing, but if you've got your hopes up for USB, then definitely have a look at the Arduino. It's a very low cost microcontroller that can run standalone, or can talk to a PC through a number of flexible interfaces (including USB).
It is extremely popular with the hobbyist community, and as such, there are a number of entry-level projects to get one started with the device. Price on Sparkfun is $35 USD for a fully assembled USB-enabled version.
I have used the concepts in this CodeProject article to successfully light up LEDs.
It might meet your requirements if:
You can use parallel port instead of usb (or maybe usb to parallal cable/dongle)
You are ready to tackle some soldering and simple electronic tinkering
You can modify the vb code to monitor your status
As the author mentions in the article, you can destroy your computer's parallel port (and worse!) if you are not very careful.
In addition, a good engineer would insist that you isolate the lights from the port to further protect the computer. (relays, triacs, opto isolators, etc.)
That being said, it does work!
The easiest solution is to buy a USB traffic light, rather than building one yourself. E.g. USB Ampel. With a simple API included, it would probably be much easier.
Traditionally people have used the X10 automation framework for this kind of thing. People at my company use it to control lava lamps to indicate the status of our continuous integration build.
There's a pointer over at How does one get started writing applications that interact with x10 protocol?
One step further is to build something yourself using a microcontroller platform like the Arduino. Some examples of what is possible with the Arduino platform are available on the Arduino Playground page.
An article on how to make traffic lights using an Arduino is available at Instructables.
Channel9 has a video from the Microsoft PDC showing how some developers use a "Build Bunny" for something similar: PDC2008 ShowOff Entry: Brian the Build Bunny
There's also more information and source code here.
Try using simple usb experimentation interfaces such as Phidgets (Www.phidgets.com) or the Velleman k8055 USB experimentation board (http://www.velleman.be/ot/en/product/view/?id=351346).
We used this product at my last job to control a set of revolving traffic lights when a build would break on our CI server. The Ethernet is nice so that you are not limited to the 3M range of USB and it is as easy as opening a TCPClient to port 10000 and sending a "1R1\r".
http://www.6bit.com/products/smartrelayE.php?products_id=33