COP 5615: Distributed Operating System Principles | Weekly Assignment Week 4: 09-13 September
We discussed the lowest levels in basic networking model i.e. physical and data link layer
There are two connection mechanism- Ethernet and Infiband. Ethernet has 4 types of network card for
high performance computing namely 100Gbps, 40Gbps, 10Gbps and 1Gbps whereas Infiband has
14Gbps and 56Gbps per channel cards. While ethernet is more widely used, Infiband advantages lies in
flatter topology, less computing power and lower latency.
Communication protocols-
There are two types of communication-
Transient communication: In this the sender discards message when it cannot be delivered at the next
server, or at the receiver.
Persistent communication: A message is stored at a communication server as long as it takes to deliver
it.
The Client server communication is based on transient synchronous communication where both client
and server have to be active at the same time and client gets blocked until it gets a reply.
SSL: For secured communication between two browser and server SSL(HTTPS) is used and which uses
public private key pair for authentication. It can be one way or two way. SSL is replaced by TLS 1.2.
SSH: It is used to encrypt message between two computers. Like one computer securely accessing
another computer.
Telnet and FTP are less secure protocols.
Messaging -
RPC: Remote Procedure Call (RPC) is a protocol to request a service from a program located in another
computer connected through a network. It uses client server model and is a sequential operation. In the
RPC model, the underlying implementation creates a stub for each remote procedure. When your
application calls the "remote procedure" the stub packs up the parameters, sends them over the next
work, invokes, the remote version of the procedure, takes the return values and send them back over
the network to the caller, the stub unpacks the return values and the application then receives them.
Both the client server has to agree to same encoding. To have asynchronous RPC we can send multiple
RPC. It works on top of socket.
A socket provides access to the transport to implement the RPC protocol. The server binds a port and
start listening on it. The client requests a connection and server accepts it. Then there is a receive send
loop where anything can be sent. It remains open until connection is closed.
-Saurabh Prasad