Atm has it's own reference model as well, the BISDN model. With respect to
the OSI model, I put the entire ATM model at the physical layer. However,
some people would put different aspects of ATM at higher layers, for example
the PNNI routing protocol, the most complex beast known to the networking
world yet.. It is a routing protocol, much like OSPF, but its still designed
for the transport across the physical medium. Its a tough call.
--
Scott Mountenay
On 20 May 2000 10:43:39 -0400, Brian Lodwick <[EMAIL PROTECTED]> wrote:
>What about -ATM ? how do you put this monster into the organized model?
>>>>Brian
>>From: "Chuck Larrieu" <[EMAIL PROTECTED]>
>>Reply-To: "Chuck Larrieu" <[EMAIL PROTECTED]>
>>To: <[EMAIL PROTECTED]>
>>Subject: RE: Connection(less) services
>>Date: Sat, 20 May 2000 07:24:57 -0700
>>
>>I saw an interesting statement in a book I was browsing recently: Ray
>>Horak,
>>in Communications Systems and Networks, calls UDP a layer seven protocol
>>while TCP is a layer four protocol. When I saw that, I immediately went to
>>my Radcom world of Protocols poster, and read their definition of layer
>>four, which does indeed say "reliable" I have not seen it argued this way
>>before, but I understand where the author is coming from. If layer four is
>>reliable, and UDP is not, it cannot be layer four.
>>
>>I know some folks warn about trying to crunch everything into the OSI
>>model.
>>I believe the purpose of studying the model is 1) to provide a structured
>>view of data communications 2) a means of structuring a troubleshooting
>>methodology 3) so one can at least be conversant with the terminology when
>>listening to all the presentations about what hardware or software operates
>>at what layer. I myself have begun to look at the world using a variant of
>>the ip model- physical/data link, network, transport, everything else.
>>Someone else on the group once suggested a box with four sections -
>>connection, connectionless on one axis and reliable, unreliable on the
>>other. As his learning process he would place a protocol into each section
>>based on the intersection. TCP = connection, reliable; frame relay PVC =
>>connection, unreliable, and so on.
>>
>>Chuck
>>
>>-----Original Message-----
>>From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of
>>Howard C. Berkowitz
>>Sent: Friday, May 19, 2000 8:42 PM
>>To: mikey; [EMAIL PROTECTED]
>>Subject: Re: Connection(less) services
>>
>> >According to the OSI model, layer 3 is connectionless and layer 4 is
>> >connection oriented. However, one must remember that the OSI model is
>> >theoretical.
>>
>>And the OSI model has been extended by ISO, considerably beyond the
>>simple seven layers. Unfortunately, the extensions, such as the
>>internal organization of the network layer, the object-oriented
>>refinements of the application layer, management, etc., are rarely
>>presented.
>>
>> >Specific protocol implementations do not necessarily adhere to
>> >the OSI model.
>>
>>Actually, the main OSI Reference Model defined in ISO 7498 was
>>connection-oriented at all levels. Connectionless operation was
>>described in one of the Annexes to 7498 -- can't tell you the
>>specific annex number from memory.
>>
>>In the actual OSI protocol suite, CLNP was the connectionless network
>>layer protocol, and the connection-mode network protocol was a
>>particular X.25 subset.
>>
>> >
>> >Example: TCP and UDP are both layer 4, one is connection oriented the
>>other
>> >is connectionless. Also, take a look at the IPX stack, it does not map
>> >nicely to the OSI model.
>>
>>
>>Quite correct.
>>
>> >
>> >mikey
>> >Oscar Rau <[EMAIL PROTECTED]> wrote in message
>> >[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
>> > > When you look at TCP and UDP applications, they are placed
>> > > in the Transport layer of the OSI model. Some of the Cisco
>> > > certification literature suggests that connection oriented
>> > > services and connectionless services are handled by Layer 3
>> > > which is the network layer.
>> > >
>> > > Which layer is primarily responsible for connection oriented
>> > > and connectionless services?
>> > >
>> > > Thank you in advance.
>> > > --
>> > >
>> > > Oscar Rau
>> > > [EMAIL PROTECTED]
>> > >
>> > > ___________________________________
>> > > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html
>> > > FAQ, list archives, and subscription info: http://www.groupstudy.com
>> > > Report misconduct and Nondisclosure violations to
>>[EMAIL PROTECTED]
>> > > ---
>> >
>> >
>> >___________________________________
>> >UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html
>> >FAQ, list archives, and subscription info: http://www.groupstudy.com
>> >Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
>>
>>___________________________________
>>UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html
>>FAQ, list archives, and subscription info: http://www.groupstudy.com
>>Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
>>
>>___________________________________
>>UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html
>>FAQ, list archives, and subscription info: http://www.groupstudy.com
>>Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
>
>________________________________________________________________________
>Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com
>
>___________________________________
>UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html
>FAQ, list archives, and subscription info: http://www.groupstudy.com
>Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
>---
___________________________________
UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html
FAQ, list archives, and subscription info: http://www.groupstudy.com
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
