Diving into the ISO OSI Network Stack Discussion
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@dafyre said in FibreChannel Switch Types:
@scottalanmiller said in FibreChannel Switch Types:
@dafyre said in FibreChannel Switch Types:
@scottalanmiller said in FibreChannel Switch Types:
@dafyre said in FibreChannel Switch Types:
... with iSCSI you can use a regular old fashioned Ethernet switch.
Can, assuming you are pumping it over Ethernet. If you put it over Token Ring, FC or other layer two option, you cannot. iSCSI is independent of this layer.
Right. iSCSI is an IP protocol, higher up in the stack at layer 4 or 5.
It's an application protocol, layer 7.
What makes it Application layer instead of Session layer?
The final layer is always application, that's where the stack has to end. A session layer communications wouldn't do anything, other than operate as a VPN - and a VPN is an incomplete stack that's running just waiting for Layer 7 to come along. iSCSI actually talks to something that isn't in the network stack, and only L7 can do that. iSCSI is the same as HTTP, SMTP, XMPP, RTP and so forth.
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Remember that nothing about iSCSI is sessions related, it's not part of the networking, its the payload from the application.
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@scottalanmiller said in FibreChannel Switch Types:
Remember that nothing about iSCSI is sessions related, it's not part of the networking, its the payload from the application.
How is it not session level? it's communication between two hosts.
If SQL belongs at the session level, then so would iSCSI.
https://blogs.cisco.com/cloud/an-osi-model-for-cloud -
@dafyre said in FibreChannel Switch Types:
@scottalanmiller said in FibreChannel Switch Types:
Remember that nothing about iSCSI is sessions related, it's not part of the networking, its the payload from the application.
How is it not session level? it's communication between two hosts.
No it is not, it is the application protocol consumed by the initiator.
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@dafyre said in FibreChannel Switch Types:
If SQL belongs at the session level, then so would iSCSI.
https://blogs.cisco.com/cloud/an-osi-model-for-cloudI don't agree with CIsco and their marketing. That does not match the actual OSI stack. iSCSI is the final deliverable of the network, it is the application "end user" product here... the payload. It doesn't interact with the stack.
SQL in that stack is misleading, it isn't like anything else there. It's many levels higher, because it obviously is L8 because you type it directly, which you never do even with L7.
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So that means you would put things like NFS, and NetBios at the application layer too? (pulling again, from the Cisco page for reference).
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@dafyre said in FibreChannel Switch Types:
So that means you would put things like NFS, and NetBios at the application layer too? (pulling again, from the Cisco page for reference).
Of course, which is where they are accepted by the industry to be and always have been. Remember that Cisco calls when they do Ethernet too, but isn't part of the standard. Cisco and standards are oil and water. That's the last place you should be looking for how networking works, they have their own agenda, they own definitions and their own compatibility.
https://en.wikipedia.org/wiki/Application_layer
iSCSI is layer 7. SQL is not part of the network at all but you can call it L8, the layer directly above the network stack. But if you've ever worked with a database, it is really obvious that SQL is a language that humans work in, so is above the stack. Just like BASH is not part of the network stack. Or PowerShell. Of a text based video games.... those are applications. Applications are above the application layer of the OSI stack, not part of it.
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To make it a little more clear, let's assume we encrypt some database traffic on a very typical network....
Database Application Itself - SQL | Layer 7 : MySQL Protocol | Layer 5/6 : TLS | Layer 4 : TCP Port 3306 | Layer 3 : IP Address 192.168.0.4 | Layer 2: Ethernet MAC Address | Layer 1 : GigE 802 Standard -
So as you can see from the example, the MySQL Protocol is the Layer 7 Application protocol, that's the protocol used by the application itself that it puts onto the wire. SQL is a language for querying the database and doesn't get placed onto the wire directly, but might sometimes be part of a payload that is handled by MySQL. But if it is part of a payload, then it is inside of the L7 MySQL protocol.
If SQL was a protocol at layer five, think of the implications. That would mean that the Adobe PDF sitting on your desktop, which is quite clearly an end user file, was actually some kind of "Network traffic in stasis".
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@scottalanmiller said in FibreChannel Switch Types:
@dafyre said in FibreChannel Switch Types:
So that means you would put things like NFS, and NetBios at the application layer too? (pulling again, from the Cisco page for reference).
Of course, which is where they are accepted by the industry to be and always have been. Remember that Cisco calls when they do Ethernet too, but isn't part of the standard. Cisco and standards are oil and water. That's the last place you should be looking for how networking works, they have their own agenda, they own definitions and their own compatibility.
https://en.wikipedia.org/wiki/Application_layer
iSCSI is layer 7. SQL is not part of the network at all but you can call it L8, the layer directly above the network stack. But if you've ever worked with a database, it is really obvious that SQL is a language that humans work in, so is above the stack. Just like BASH is not part of the network stack. Or PowerShell. Of a text based video games.... those are applications. Applications are above the application layer of the OSI stack, not part of it.
Wikipedia is not a good place to go, lol. I had this open in my browser tab already...
https://en.wikipedia.org/wiki/List_of_network_protocols_(OSI_model)
Which puts iSCSI at Layer 4, and NetBios, NFS and a few others at Layer 5.
My page has been more recently updated. I win.
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Seriously though. How you would fill out the OSI model?
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@dafyre said in FibreChannel Switch Types:
@scottalanmiller said in FibreChannel Switch Types:
@dafyre said in FibreChannel Switch Types:
So that means you would put things like NFS, and NetBios at the application layer too? (pulling again, from the Cisco page for reference).
Of course, which is where they are accepted by the industry to be and always have been. Remember that Cisco calls when they do Ethernet too, but isn't part of the standard. Cisco and standards are oil and water. That's the last place you should be looking for how networking works, they have their own agenda, they own definitions and their own compatibility.
https://en.wikipedia.org/wiki/Application_layer
iSCSI is layer 7. SQL is not part of the network at all but you can call it L8, the layer directly above the network stack. But if you've ever worked with a database, it is really obvious that SQL is a language that humans work in, so is above the stack. Just like BASH is not part of the network stack. Or PowerShell. Of a text based video games.... those are applications. Applications are above the application layer of the OSI stack, not part of it.
Wikipedia is not a good place to go, lol. I had this open in my browser tab already...
https://en.wikipedia.org/wiki/List_of_network_protocols_(OSI_model)
Which puts iSCSI at Layer 4, and NetBios, NFS and a few others at Layer 5.
My page has been more recently updated. I win.
SO they are claiming that no socket is used for iSCSI traffic? That it replaced TCP?
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@dafyre said in FibreChannel Switch Types:
Seriously though. How you would fill out the OSI model?
Excellent question
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@dafyre said in FibreChannel Switch Types:
Seriously though. How you would fill out the OSI model?
What do you mean?
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@scottalanmiller said in FibreChannel Switch Types:
@dafyre said in FibreChannel Switch Types:
Seriously though. How you would fill out the OSI model?
What do you mean?
He means that you define things differently than what we understand of the OSI model although that may just be our misunderstanding of it
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@dafyre said in FibreChannel Switch Types:
@scottalanmiller said in FibreChannel Switch Types:
@dafyre said in FibreChannel Switch Types:
So that means you would put things like NFS, and NetBios at the application layer too? (pulling again, from the Cisco page for reference).
Of course, which is where they are accepted by the industry to be and always have been. Remember that Cisco calls when they do Ethernet too, but isn't part of the standard. Cisco and standards are oil and water. That's the last place you should be looking for how networking works, they have their own agenda, they own definitions and their own compatibility.
https://en.wikipedia.org/wiki/Application_layer
iSCSI is layer 7. SQL is not part of the network at all but you can call it L8, the layer directly above the network stack. But if you've ever worked with a database, it is really obvious that SQL is a language that humans work in, so is above the stack. Just like BASH is not part of the network stack. Or PowerShell. Of a text based video games.... those are applications. Applications are above the application layer of the OSI stack, not part of it.
Wikipedia is not a good place to go, lol. I had this open in my browser tab already...
https://en.wikipedia.org/wiki/List_of_network_protocols_(OSI_model)
Which puts iSCSI at Layer 4, and NetBios, NFS and a few others at Layer 5.
My page has been more recently updated. I win.
https://en.wikipedia.org/wiki/ISCSI
That page shows iSCSI as riding on top of TCP, not replacing it. And it gets port numbers. Only L7 services get port numbers, AFAIK. I don't know of any exception to that.
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@wirestyle22 said in FibreChannel Switch Types:
@scottalanmiller said in FibreChannel Switch Types:
@dafyre said in FibreChannel Switch Types:
Seriously though. How you would fill out the OSI model?
What do you mean?
He means that you define things differently than what we understand of the OSI model although that may just be our misunderstanding of it
I just gave an example though. It's hard to say why you see it differently as my understanding of the model is my understanding of it
Other than things floating between L5 and L6 as a natural consequence of TCP/IP being a four layer model, I don't see these as really convoluted. iSCSI, for example, is the payload of the network stack, so L7 without question. How could it be anything else? SQL Isn't part of that stack, quite obviously. What makes it seem like it is, other than some confused kid at Cisco making a chart - this is Cisco that told a Spicecorps that without 14Tb/s you couldn't watch YouTUbe. -
So my question then would be, in your view of the OSI model and what iSCSI does, where would you put it in the stack knowing that it is the "final deliverable" of the communications in question and that it will be consumed directly by the final application and that it plays no role in the delivery, it is the thing "to be delivered." Where would you put it knowing what it is?
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Likewise, where do you picture things like PDF, HTML, Word, SQL and other "file formats" that are not networking components at all but are document formats used internally by humans or applications? Would you put them into the networking stack even though they are file formats? And what role do they play when sitting on disk? Is the disk a "time frozen" snap of the network? If Word is an underpinning network component, what application protocol rides on top of it?
