Understanding Protocols

[storeyalan]

When we talk about router implemented “protocols” (eg HDLC, PPP ) are we talking about hard code embedded into the router IC’s, which, when instructed by IOS coding, performs a specific task on data ( ie HDLC or PPP data encapsulation). Or is it part of the IOS itself ?

When we talk about “other” “protocols”, are we talking about operating system executables or kernel code, which performs a specific task on data prior to transmission/reception via the NIC..

I keep hearing the term protocol but would like to see some code or view an executable somewhere (if you get my meaning)

So far the term protocol has not been demonstrated, merely referred to………..

As an example, when referring to a hard disk, we can take a lid off a pc, point to the hard disk, remove it and even take the disk lid off.

Can we somehow do the same with protocols ?

I realise a protocol is merely a set of rules, BUT the protocol still has to be implemented. How is this done ?

Alan

[scottmac]

"Protocol" as a term, refers to a set of rules ... nothing more, nothing less. I.e., "If you want to talk to me across this serial link, your system must deliver the information using this binary format (signaling protocol), the binary information must translate into this frame format (ethernet protocol), and use a specific set of code so that the information can be directed up the (TCP/IP protocol) stack and sent to the right process."

If you want tangible material to examine the rules, then you look in the rulebook ... which in this case are the collection of RFCs generated since the inception of the Internet.

Other protocols can be reviewed by reading the IEEE specs for the given protocol, or the agreements (conventional rules, not necesarily "the law") created by the various Forums (ATM Forum, Frame-Relay Forum, etc.)

If you want to see the protocols "in action," then you'll need the proper analyzer; for example, to see TCP/IP and / or Ethernet in action, connect something like an NAI Sniffer or Ethereal to your LAN and watch the various handshakes, acknowledgements, and broadcasts.

The protocol itself is conceptual, you can read about the concept. To see the effects of the protocol, you need something to translate it into a visible medium ... like a Sniffer / Ethereal.

Good Luck

Scott

[storeyalan]

I understand your explanation, however looking at your last sentence, something "conceptual" cannot have an "effect". Only something real can have an effect on something else. Take a simple frame transmitted over the WAN. Unless both WAN interfaces are set for say PPP, then they will not recognise the frame. Therfore it follows that the WAN interface must be referencing or calling upon a PPP protocol in order to "encode" or "decode" the packet.

Webopedia explanation for protocol states the protocol is implemented in hardware or software. http://www.webopedia.com/TERM/p/protocol.html

Therfore either the router IOS or onboard ic's carry out the encapsulation. Therfore it follows code must exist to carry out this action. What do you think ?

Alan

[scottmac]

The hardware and / or software are producing the effect according to the concepts of the protocol.

The hardware and / or software must have rules to follow or a goal to accomplish ... those are the protocols established by any of the aforementioned comittees or standards bodies.

I'm sticking with "Protocols are Rules;" how the protocols are executed is a different issue

For example, in the US, if you want prescription drugs, you go to the doctor, he prescribes 'em, and you pick 'em up at a pharmacy.

It doesn't matter matter HOW you got to the doctor or the pharmacy ... drive a car, ride a bike, walk, skateboard ... doesn't matter ... the protocol says you just have to pick them up (or in some rare cases, have them delivered).

It also doesn't matter how the doctor notifies the pharmacy that you are entitled to the medication; he can write a 'scipt, call it in, fax it in ... he just has to notify the place that you are entitled to collect the medication if you choose to do so.

Protocol is one thing, execution of the protocol is another.

FWIW

Scott

[storeyalan]

OK, I see where you are coming from. I suppose I am more interested in finding out an example of protocol implementation and how this is done in hardware or software. I'm studying at the moment and when learning about something I like to follow it right to the "nth" degree. In this case seeing an example of protocol implementation. I'm not really sure where to go from here, but you've certainly helped.

Alan - UK

[scottmac]

Another source for "nuts & bolts" info on how a protocol functions might be the programming libraries and/or class references ("class" being a module of programming code).

For example, if you were to look up "gethostbyname" you see what information must be passed to the process, and the expected return info relative to a DNS request.

Most networking applications & OpCode is not done "from scratc" by hand; usually it is done by building from existing modules (classes and methods) within the programming language (C, C++, C#, Java ...).

Looking through the references for these classes and methods would likely give you some insight as to how the specific protocols work (at least at the software level).

If ou poke around some of the microcontroller boards, there are also some examples of coding to specific protocols, including ethernet, usb, and firewire.

Some popular microcontrollers are Intel 8051 (and similar) , Zilog Z80 Acclaim! and Encore!, Blackfin, PIC (16x, 18x series), Atmel, and many more ...

Just a thought.

Good Luck

Scott