Network in Nachos

Here we are going to show you a little introduction of how networking works in NachOS.

In Nachos we have two main classes: 

The network class

The postoffice class

Network

The network class is not directly used by the user. It is the Link between nachOS and sockets TCP/IP.

It has four methods:

• Send: Sends a packet to a NachOS machine.
• Receive: If there is a packet, it receives it. If not, it returns with a 0.
• CheckPktAvail: It activates regularly to verify if a packet arrives.
• SendDone: When it receives the packet, it calls a manager  in order to organize it.

For communication, NachOS uses PacketHeader and MailHeader.

They both contain:

To (Destination of the packet)

From (Origin of the packet)

Length (Size of the packet)

Postoffice

Example of postoffice

• Sends a packet to a given address
• Waits for a message and prints it once received
• Sends another packet to the same address
• Waits for a message and prints it once received

Now we are going to explain some other important files in the network folder and we are going to show you some code

• nettest.cc  (nachos/code/network)

Here is where we run the routines of the network test.

• post.h, post.cc  (nachos/code/network)

They help to synchronize the data sent and received. (like a messenger)

Here we show you some code 

Post.h

       Post.cc

• network.h, network.cc (nachos/code/machine)

They are a physical network hardware emulation. 

Network.h

        Network.cc

References:


bit.ly/vtlhRr