| Author |
Message |
CJ
Guest
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 Posted:
Tue Apr 12, 2005 8:18 pm Post subject:
Re: OSI Model |
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I understand how OSI works in general. But I can know alot of information
about alot of things....doesn't mean its of any use to me.
From what I am reading knowing the OSI is a "nice to know" thing, but
knowing it, unless I am a protocol developer or something, is useless to me.
Sound about right?
"catwalker63" <_catwalker63_@hotmamamail.com> wrote in message
news:Xns9635D5BA2DD3Bcatwalker63athotmail@216.196.97.136...
| Quote: | "CJ" <chrisj@illicom.net> prattled ceaslessly in
news:AwH6e.689$Cz3.64167@monger.newsread.com:
I studied the OSI model, but nobody could ever tell me why I need to
know it.
The answer I always got was "you definitely need to know the OSI
model" but when I ask why I always get "you just do".
Can anyone tell me why I need to know it and how I would apply the
knowledge? Perhaps a lab exercise or something??
Thanks,
CJ
The OSI model is a theoretical model that specifies, in a very general
way, how data gets from the application on one machine across the network
to the application on another machine. There are no labs unless you are
developing a protocol to operate at a layer in the model. Understanding
the model helps you undestand how the protocols fit together to get data
onto the network and back off of it.
--
Catwalker
aka Pu$$y Feet
BS, MCP, MCSA
MCNGP #43
www.mcngp.com
faq.mcngp.com
"If man could be crossed with the cat, it would improve man, but it would
deteriorate the cat." Mark Twain |
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catwalker63
Guest
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| Posted:
Tue Apr 12, 2005 8:48 pm Post subject:
Re: OSI Model |
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"CJ" <chrisj@illicom.net> prattled ceaslessly in
news:12W6e.726$Cz3.75041@monger.newsread.com:
| Quote: | I understand how OSI works in general. But I can know alot of
information about alot of things....doesn't mean its of any use to me.
From what I am reading knowing the OSI is a "nice to know" thing, but
knowing it, unless I am a protocol developer or something, is useless
to me.
Sound about right?
|
No, it is useful to know if you want to understand how networks work. It
is also necessary if you are contemplating any type of certification in
networking. Those layers will come up over and over again.
--
Catwalker
aka Pu$$y Feet
BS, MCP, MCSA
MCNGP #43
www.mcngp.com
faq.mcngp.com
"If man could be crossed with the cat, it would improve man, but it would
deteriorate the cat." Mark Twain |
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Al Dykes
Guest
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| Posted:
Tue Apr 12, 2005 10:22 pm Post subject:
Re: OSI Model |
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In article <Xns9636484FCB54Ecatwalker63athotmail@216.196.97.136>,
catwalker63 <_catwalker63_@hotmamamail.com> wrote:
| Quote: | James Knott <james.knott@rogers.com> prattled ceaslessly in
news:ouqdnYBYXaCkOsbfRVn-pg@rogers.com:
Patrick Schaaf wrote:
Definitely not. The OSI model has no relevance in practice.
Actually, at one time, it was intended to be the "standard", but
instead, TCP/IP became the defacto standard.
http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/osi_prot.htm
The OSI model is not a protocol suite. TCP/IP is a protocol stack based
on the OSI or DOD model. TCP/IP did not replace the OSI model, it
followed it. The OSI model is a very general specification for how to
build a protocol stack.
--
Catwalker
aka Pu$$y Feet
BS, MCP, MCSA
MCNGP #43
www.mcngp.com
faq.mcngp.com
"If man could be crossed with the cat, it would improve man, but it
would deteriorate the cat." Mark Twain
|
IP and parts of the ISO _standard_ were co-developed. The problem is
that RFC standards process emphesised practical working functionality
designed by the programers that wrote the code as they went and the
OSI standard was written by teco engineers who included every function
they could think of without any thought of was it was possibe to code.
It took years for products based on OSI mode to be useful.
--
a d y k e s @ p a n i x . c o m
Don't blame me. I voted for Gore. |
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James Knott
Guest
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| Posted:
Wed Apr 13, 2005 11:07 am Post subject:
Re: OSI Model |
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catwalker63 wrote:
| Quote: | Actually, at one time, it was intended to be the "standard", but
instead, TCP/IP became the defacto standard.
http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/osi_prot.htm
TCP/IP is a protocol suite. The OSI model is a general model for
networking. TCP/IP follows the OSI and DOD model and the various
protocols in the suite fit into the model at different layers.
|
At one time, OSI was intended to be the common networking method, but didn't
make it. It was at that point that it was declared a "model". |
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James Knott
Guest
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| Posted:
Wed Apr 13, 2005 11:11 am Post subject:
Re: OSI Model |
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catwalker63 wrote:
| Quote: | It's just a method of learning the general layers of the protocol
stack. It's also a stack that was intended to be used, but was soon
surpassed by TCP/IP.
Once again, OSI is not a protocol stack. It is a general model that was
actually followed when developing TCP/IP as well as other protocol
stacks.
|
From http://www.tcpipguide.com/free/t_HistoryoftheOSIReferenceModel.htm
"One interesting aspect of the history of the OSI Reference Model is that
the original objective was not to create a model primarily for educational
purposes-even though many people today think that this was the case. The
OSI Reference Model was intended to serve as the foundation for the
establishment of a widely-adopted suite of protocols that would be used by
international internetworks-basically, what the Internet became. This was
called, unsurprisingly, the OSI Protocol Suite.
However, things didn't quite work out as planned. The rise in popularity of
the Internet and its TCP/IP protocols met the OSI suite head on, and in a
nutshell, TCP/IP won. Some of the OSI protocols were implemented, but as a
whole, the OSI protocols lost out to TCP/IP when the Internet started to
grow." |
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Al Dykes
Guest
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| Posted:
Wed Apr 13, 2005 1:08 pm Post subject:
Re: OSI Model |
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In article <8P2dndeaErgeYMHfRVn-sA@rogers.com>,
James Knott <james.knott@rogers.com> wrote:
| Quote: | catwalker63 wrote:
Actually, at one time, it was intended to be the "standard", but
instead, TCP/IP became the defacto standard.
http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/osi_prot.htm
TCP/IP is a protocol suite. The OSI model is a general model for
networking. TCP/IP follows the OSI and DOD model and the various
protocols in the suite fit into the model at different layers.
At one time, OSI was intended to be the common networking method, but didn't
make it. It was at that point that it was declared a "model".
|
You need a smiley after that. The ISO folks were very serious about a
model.
--
a d y k e s @ p a n i x . c o m
Don't blame me. I voted for Gore. |
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Al Dykes
Guest
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| Posted:
Wed Apr 13, 2005 1:11 pm Post subject:
Re: OSI Model |
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|
In article <8P2dndaaErjJY8HfRVn-sA@rogers.com>,
James Knott <james.knott@rogers.com> wrote:
| Quote: | catwalker63 wrote:
It's just a method of learning the general layers of the protocol
stack. It's also a stack that was intended to be used, but was soon
surpassed by TCP/IP.
Once again, OSI is not a protocol stack. It is a general model that was
actually followed when developing TCP/IP as well as other protocol
stacks.
From http://www.tcpipguide.com/free/t_HistoryoftheOSIReferenceModel.htm
"One interesting aspect of the history of the OSI Reference Model is that
the original objective was not to create a model primarily for educational
purposes-even though many people today think that this was the case. The
OSI Reference Model was intended to serve as the foundation for the
establishment of a widely-adopted suite of protocols that would be used by
international internetworks-basically, what the Internet became. This was
called, unsurprisingly, the OSI Protocol Suite.
|
Instead of "model" a better word would be to call it an architecture
for communications between objects. It was open ended. So was the RFC
process developed IP, for that matter.
--
a d y k e s @ p a n i x . c o m
Don't blame me. I voted for Gore. |
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| Back to top |
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David Ross
Guest
|
| Posted:
Wed Apr 13, 2005 8:07 pm Post subject:
Re: OSI Model |
|
|
| Quote: | IP and parts of the ISO _standard_ were co-developed. The problem is
that RFC standards process emphesised practical working functionality
designed by the programers that wrote the code as they went and the
OSI standard was written by teco engineers who included every function
they could think of without any thought of was it was possibe to code.
It took years for products based on OSI mode to be useful.
|
Yep. In the 80s when this was being done it was very apparent that the
folks running the ISO process were from the mainframe sized side of the
camp. Of course this was when minicomputers and PCs were exploding and a
single meg of ram was a big deal. For many systems at the time to give
up all their ram to a protocol stack that no one was really using doomed
it from the start. And to be honest TCP/IP didn't even work very well
until the ram situation improved. These protocols need buffers to work
well. :) |
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Al Dykes
Guest
|
| Posted:
Wed Apr 13, 2005 8:25 pm Post subject:
Re: OSI Model |
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|
In article <ScGdnR6NDr-K4cDfRVn-og@portbridge.com>,
David Ross <news02@raleighthings.com> wrote:
| Quote: | IP and parts of the ISO _standard_ were co-developed. The problem is
that RFC standards process emphesised practical working functionality
designed by the programers that wrote the code as they went and the
OSI standard was written by teco engineers who included every function
they could think of without any thought of was it was possibe to code.
It took years for products based on OSI mode to be useful.
Yep. In the 80s when this was being done it was very apparent that the
folks running the ISO process were from the mainframe sized side of the
camp.
|
Worse. ISO was the international side of Ma Bell and the rest of the
telecom industry which for many countries was part of it's national
postal service.
The mainframe vendors were busy building their own proprietary
networks; SNA (IBM) and DECNET (DEC) were the big ones. IP was in the
universities and research labs. At least these products worked, within
the family. It's a stretch to say that overall the X. standards ever
came up to expectations.
Of course this was when minicomputers and PCs were exploding and a
| Quote: | single meg of ram was a big deal. For many systems at the time to give
up all their ram to a protocol stack that no one was really using doomed
it from the start. And to be honest TCP/IP didn't even work very well
until the ram situation improved. These protocols need buffers to work
well. :)
|
--
a d y k e s @ p a n i x . c o m
Don't blame me. I voted for Gore. |
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| Back to top |
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Robert Redelmeier
Guest
|
| Posted:
Wed Apr 13, 2005 8:44 pm Post subject:
Re: OSI Model |
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David Ross <news02@raleighthings.com> wrote:
| Quote: | Yep. In the 80s when this was being done it was very
apparent that the folks running the ISO process were from
the mainframe sized side of the camp. Of course this was
when minicomputers and PCs were exploding and a single
meg of ram was a big deal. For many systems at the time to
give up all their ram to a protocol stack that no one was
really using doomed it from the start. And to be honest
TCP/IP didn't even work very well until the ram situation
improved. These protocols need buffers to work well. :)
|
I think TinyTCP will run nicely in 50 kB. The bigger problem was there
usually was no-one to talk to. When there was, no-one minded 50 kB of
lock-down after around 1980 or so when at least 16 kb chips existed.
Prior to that, UUCP ruled because it needed much less (2 kB?).
-- Robert |
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CJ
Guest
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| Posted:
Wed Apr 13, 2005 10:03 pm Post subject:
Re: OSI Model |
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|
"J. Clarke" <jclarke.usenet@snet.net.invalid> wrote in message
news:d3heph0dnm@news3.newsguy.com...
| Quote: | CJ wrote:
I understand how OSI works in general. But I can know alot of
information
about alot of things....doesn't mean its of any use to me.
From what I am reading knowing the OSI is a "nice to know" thing, but
knowing it, unless I am a protocol developer or something, is useless to
me.
Sound about right?
Until some guy in a job interview asks you to explain your understanding
of
the OSI model.
|
Which is fine...but it still is useless to me otherwise. Ok...so I know how
a packet is created on one end and deconstructed on the other....phffft.
| Quote: |
"catwalker63" <_catwalker63_@hotmamamail.com> wrote in message
news:Xns9635D5BA2DD3Bcatwalker63athotmail@216.196.97.136...
"CJ" <chrisj@illicom.net> prattled ceaslessly in
news:AwH6e.689$Cz3.64167@monger.newsread.com:
I studied the OSI model, but nobody could ever tell me why I need to
know it.
The answer I always got was "you definitely need to know the OSI
model" but when I ask why I always get "you just do".
Can anyone tell me why I need to know it and how I would apply the
knowledge? Perhaps a lab exercise or something??
Thanks,
CJ
The OSI model is a theoretical model that specifies, in a very general
way, how data gets from the application on one machine across the
network
to the application on another machine. There are no labs unless you are
developing a protocol to operate at a layer in the model. Understanding
the model helps you undestand how the protocols fit together to get data
onto the network and back off of it.
--
Catwalker
aka Pu$$y Feet
BS, MCP, MCSA
MCNGP #43
www.mcngp.com
faq.mcngp.com
"If man could be crossed with the cat, it would improve man, but it
would
deteriorate the cat." Mark Twain
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net) |
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James Knott
Guest
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| Posted:
Wed Apr 13, 2005 10:58 pm Post subject:
Re: OSI Model |
|
|
Al Dykes wrote:
| Quote: | At one time, OSI was intended to be the common networking method, but
didn't make it. It was at that point that it was declared a "model".
You need a smiley after that. The ISO folks were very serious about a
model.
|
Please check the info and link I posted in another message. |
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Al Dykes
Guest
|
| Posted:
Thu Apr 14, 2005 1:28 am Post subject:
Re: OSI Model |
|
|
In article <aHg7e.780$Cz3.87456@monger.newsread.com>,
CJ <chrisj@illicom.net> wrote:
| Quote: | "J. Clarke" <jclarke.usenet@snet.net.invalid> wrote in message
news:d3heph0dnm@news3.newsguy.com...
CJ wrote:
I understand how OSI works in general. But I can know alot of
information
about alot of things....doesn't mean its of any use to me.
From what I am reading knowing the OSI is a "nice to know" thing, but
knowing it, unless I am a protocol developer or something, is useless to
me.
Sound about right?
Until some guy in a job interview asks you to explain your understanding
of
the OSI model.
Which is fine...but it still is useless to me otherwise. Ok...so I know how
a packet is created on one end and deconstructed on the other....phffft.
|
You'll use it to understand some new service you haven't heard of yet
or to explain something to someone else. For instance:
http://www.pt.com/tutorials/ss7/stack.html
--
a d y k e s @ p a n i x . c o m
Don't blame me. I voted for Gore. |
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Al Dykes
Guest
|
| Posted:
Thu Apr 14, 2005 1:58 am Post subject:
Re: OSI Model |
|
|
In article <trSdnQnG-NCAOcDfRVn-sg@rogers.com>,
James Knott <james.knott@rogers.com> wrote:
| Quote: | Al Dykes wrote:
At one time, OSI was intended to be the common networking method, but
didn't make it. It was at that point that it was declared a "model".
You need a smiley after that. The ISO folks were very serious about a
model.
Please check the info and link I posted in another message.
|
I did, and didn't agree with it. Maybe we were quibbling over words.
G*d knows enough words were spilled in this topic in the late
70s/early 80s. The goal was, of course, to create specifications for
interoperable protocols that many companies could implement. But
those protocols are not the model. I'll agree that the use of the
model to describe protocols unrelated to X.dot was probably
unintended.
People forget that the full phrase was "ISO Reference Model". Google
for that and you'll find article after article saying that the purpose
was (and still is) to be a framework for interoperability.
For instance:
www.scit.wlv.ac.uk/~jphb/comms/std.7layer.html
ISO in association with CCITT have produced a model for Open
Systems Interconnection. This is a very loose standard which
promotes the development of protocols designed to permit open
systems interconnection. It also functions as a framework into
which existing standards may be slotted. It should act as an
aid in designing future protocol standards.
See this URL for an example of how the model is used to describe SS7,
which is NOT compatible with the X.dot standards.
http://www.pt.com/tutorials/ss7/stack.html
--
a d y k e s @ p a n i x . c o m
Don't blame me. I voted for Gore. |
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James Knott
Guest
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| Posted:
Thu Apr 14, 2005 10:51 am Post subject:
Re: OSI Model |
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Al Dykes wrote:
| Quote: | I did, and didn't agree with it. Maybe we were quibbling over words.
G*d knows enough words were spilled in this topic in the late
70s/early 80s. The goal was, of course, to create specifications for
interoperable protocols that many companies could implement. But
those protocols are not the model. I'll agree that the use of the
model to describe protocols unrelated to X.dot was probably
unintended.
People forget that the full phrase was "ISO Reference Model". Google
for that and you'll find article after article saying that the purpose
was (and still is) to be a framework for interoperability.
|
It currently is a "model", but as someone else mentioned, it wasn't a model
for TCP/IP, which was in service before there was an ISO stack. You'll
also find TCP/IP doesn't quite line up with ISO. Also, you can find a lot
of stuff on the net, that isn't entirely accurate. |
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