Peer Communication

[derkit]

Reading about the infamous OSI model, and have come across the term "Peer Communication".

Is it simply, an appearance of what happens with all information sent across a network?

I know that for two different systems to communicate with each other, the data needs to go down through all the layers (being encapsulated a bit more each time), across the physical layer to the recipient machine, and then back up the layers (being decapsulated) to the same layer that it left on the sending machine. Is this process another way of saying peer communication, ie all comms-through-the-layers is peer communication?

I've checked Exam Cram 2 and Meyers to really no avail of the term.

[dmarsh26]

Peer to Peer is an architectural model as opposed to Client-Server etc.

http://en.wikipedia.org/wiki/Peer-to-peer

Both models use the same network infrastructure and libraries, its the architecture and application layer protocols that define how they are used. Which machines talk to who and when...

[hbroomhall]

I understand it to mean the concept that each layer communicates with its equivalent layer on the other machine.

To illustrate this I'd offer a page from my favourite book.

Edit: I'm assuming you didn't mean 'Peer to peer'

Harry.

[derkit]

Originally Posted by hbroomhall

I understand it to mean the concept that each layer communicates with its equivalent layer on the other machine.

To illustrate this I'd offer a page from my favourite book.

Edit: I'm assuming you didn't mean 'Peer to peer'

Harry.

Thanks Harry and dmarsh for the super quick response

Harry - that's exactly what I was reading about - it seemed like it was a label for a concept, I just wanted to make sure it wasn't trying to explain something else and I wasn't getting it! phew!

[derkit]

The link you gave - the TCP/IP guide - is it something worth bookmarking for my level (very entry-level networking!!) ?

[dmarsh26]

I've said it before and i'll say it again, the OSI 7 layer model is a THEORETICAL MODEL, it does not exist, nobody ever implements it, it exists to describe a theorectial architecture of how communications takes place. It provides a rough framework for people to work within, but they can and do deviate from it.

Imagine you are creating you own computer, and your own OS, and your own communications stack, how would you go about it ? I have worked on projects that have done this, and they did not reference the 7 layer model once, but they did broadly adhere to its principles, because they are sound layered architecture principals.

For example how might the same program work over serial RS232, Ethernet and other physical mediums without a layered architecture ? Reuse is obtained and higher reliability and less code to test by creating reusable modules in each layer that are interchangeable.

Look here :-

http://en.wikipedia.org/wiki/Transport_layer

Describes OSI 7 layer and TCP/IP 5 layer models/architectures.

[derkit]

Originally Posted by dmarsh26

I've said it before and i'll say it again, the OSI 7 layer model is a THEORETICAL MODEL.

Sorry about you having to say it again - I haven't really given it much thought until now.

Sounds like quite a few principles where its good to have a general direction to go in, but the exact details can be as fluid as you like.

Will have a look at that link also.

[dmarsh26]

http://www.certforums.co.uk/forums/thread19423.html#12

Sorry derkit, guess I should post when I don't have a headache !