I have two question about simulation on QulaNet simulator:
I want to build a network on QualNet Simulator, each node in this network send a message [application layer message] to other nodes in its range. I read in the manual there are two types of application layer protocol, one for generating traffic (ex: CBR), and one for application layer routing protocol(ex: BellmanFord), i wonder which type i should follow to apply what i mentioned in the first two lines.
I think there is no need to any routing protocol, in the GUI there is a "None" choice, but i didn't find the source code of it yet ! Where i can find it.
Thanks,
Dont confuse with Bellmanford and CBR protocols.Bellmanford is a routing protocol but they placed under Application layer for their programming convienience.
CBR is your actual Data traffic so you can see all the statistics related to your data traffic under cbr(client,server).When coming to network routing protocol in QulaNet if you did not configured any routing protocol by default it will take Bellmanford as routing protocol for which you can see the statistics under application layer.
Related
I am completely new to ns3. All the tutorials that are given in the repo mainly consist of echo servers where they are sending a packet of specific size and receiving the echo. I want to design a real world scenario where the server offers some service. e.g. the client node takes a string in lower case as input and sends to server. The server changes it to upper case and returns to client and client prints it on console. How to model this exact situation in ns3 ? I could not get any solution even after searching for a lot of time and I am not getting any way of actually interacting with the user in ns3.
Your question is very general and cannot be answered in a few lines. You can find the ns3 repository here LoRaWAN ns-3 module. It contains end devices, a gateway, and a server. A server is responsible for interacting with end devices in many ways. For example, the network server can control the end device's data rate, transmit power, and bandwidth. It also notifies end devices with downlink acknowledgment through a gateway. Based on my opinion, this module can be helpful for your mentioned scenario. If you do not want to violate the tcp/ip protocol stack you should modify the MAC commands used in this module to fulfill your needs.
I am struggling to describe simply what the IP Application layer actually “is”. Some of my terminology may be “not quite right”, so I am happy to be corrected on my terminology as well. Is the application layer a “thing”? Or is it more “conceptual” than that? Is the Application layer on a particular node solely that collection of protocols (such as FTP, POP3, HTTP) that an application needs to adhere to if it is to successfully communicate with another remote application?
Conversely, if I write a program that does not strictly conform to an application protocol (say FTP) then there is nothing in the local “application layer” that will “stop” my attempt to communicate to the remote end using an invalid command? Whereas, if the remote end does conform to the application protocol, then it will reject or ignore my invalid communication attempt?
Or again, I could define my own protocol (not necessary as I guess all scenarios are already covered), and as long as my protocol was “robust and consistent” I could use it to communicate between two remote applications and everything would work? Or, is the Application layer a “thing” separate from the protocols?
The application layer is everything that's inside the application - that is, not within the IP stack (which covers network and transport layers).
If you want your application to communicate with an FTP server it needs to be able to speak FTP in order to work. If you write your own client-server protocol you can do whatever you want.
The network layers are there to make your life easier and to make applications compatible with each other. You can use or not use whatever you seem fit.
“An application needs to communicate with another application on a remote system. Any communication can be thought of as the exchange of messages and data between two partners. There are rules (protocols) that define for an application: what commands are available, the sequence that they can be exchanged between partners and any limitations on the data exchanged. For example: communication with an HTTP server uses commands: GET, POST and PUT (and others), whereas communication with an SMTP (mail) server uses: MAIL, RCPT and DATA, and similarly for other protocols. There are different protocols depending on the nature of the communication e.g. text message transfer, file transfer or video streaming. Any commands that are sent by either partner that do not obey those protocol rules is either: not delivered to, ignored or rejected by the remote application. Nothing prohibits application partners using their “own” communication protocol – for example Skype developed an uses its own protocol. However, there are standard protocols that handle most conceivable communication needs, so developing a new protocol may be unnecessary. If an application uses a “private” protocol its communication will be limited to remote applications that support the same private protocol. In addition to protocols, in a practical, real-world, system there are programming libraries (Programming interfaces) that enable the end-user application to request and participate in this communication. It is the end-user application’s responsibility to interact (send and receive data and parameters) with the (local programming) interface and the comms system’s responsibility to process those requests and deliver the data. In simplistic terms, one data transmission starts at one application and ends at another. However, IP provides other applications, such as DNS, that are used to set up connections, but the operation of these is not visible at the end-user application level. In summary, the collection of protocols and the programming interfaces available and used by an end-user application is the application layer on a system.”
We're prototyping a jgroups-based cluster node messaging system that will replace one that was JDBC-based. There are a lot of folks in my organization who are concerned about adding more multicast traffic to an already busy network, so I'm getting some pushback on a UDP/multicast solution.
I know JGroups can be configured to be TCP only, but I do not want to have to force a configuration step into the application where each node has to be identified ahead of time in a config file.
What I'd like then is to see if we can get a hybrid working here where multicast is used ONLY for group membership operations (discovery, heartbeats, failure detection), but messaging is all TCP-based.
I'm not finding examples of that in my searches, however, and am therefore questioning whether JGroups can be configured this way.
Can it, and any example configs showing how?
Thanks!
As for discovery, using MPING you can do that - it uses IP multicast to discover new nodes, although these later respond via the main transport (TCP in your case).
As for FD/FD_ALL, I don't think it's possible, the protocols are designed to use the main transport. You'd have to write your own FD protocol, shouldn't be that complicated.
However, if you can use UDP, you probably should. It's up to you whether you send a message to one node, multiple ones or all of them - for one destination there will be unicast UDP, for few destinations (if you set the anycast option) will be multiple unicasts used and only for all nodes the UDP will reduce the network load by multicasting. It's really up to the application, UDP just allows multicasts.
I'm writing a bit of desktop software which has two components. Component B queries component A. Creating a web service seems like an ideal way to do IPC in principle. The data model fits, there are ready-made client and server libraries, a well known way to encode and decode parameters etc.
But setting up an HTTP server on a network socket doesn't seem right for a local application. For example what port do I choose? I don't really want people to be able to scan and talk to the app from outside etc.
So I was thinking that I might be able to do HTTP over a domain socket. Does that make any sense? Is there any precedence for it? Is there an equivalent protocol that I could use for IPC which has the same properties as HTTP (requests for specified resources (URIs), encoded parameters, response)?
Looking for C libraries (and possibly Go and ObjC for bonus points).
Binding to the loopback interface only (127.0.0.1) solves your "external visibility" problem, only processes on the local machine will be able to connect.
It does not solve your port allocation problem though, the port number you choose might be taken by the time your app starts. Then your server can't bind and your client connects to the other process bound to your port.
Old, less hip, but CORBA implementations tend to have the problems you have not thought of yet figured out already.
My app needs to access two network cards. One to receive data (eth0) and another to send data (3G modem).
Normally, the kernel force the app to work with only one card at a time.
Is there any thing that I can do to make it run?
Thank you.
The kernel does no such thing.
The kernel will route your traffic to the most appropriate end destination based upon the routing information and networks each card is assigned. However, if you are using TCP, your bidirectional communication will use only one route as there is only one address associated with that connection.
If you are trying to implement an multi-homing send/receive system, this is not supported in normal TCP - you will need to use a different protocol, likely implemented in the kernel.
The kernel is not forcing you to use a single interface. It just chooses a default interface if you don't specify otherwise. You can specify a specific interface by specifying it's IP address in the bind() command. To get a list of the available interfaces and their names, use the ioctl(SIOCGIFCONF) function.
Here's an example: http://techpulp.com/2008/10/get-list-of-interfaces-using-siocgifconf-ioctl/
You can make two different UDP sockets bind to separate NICs with the bind(2) and send on one and listen on the other.