Diving into the ISO OSI Network Stack Discussion
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@dafyre said in FibreChannel Switch Types:
In general, with FibreChannel devices would use a switch made and built specifically for FibreChannel... Right? (Except for FCoE)
Right FCoE is FC encapsulated over Ethernet. So that would still use an Ethernet switch. But iSCSI over TCP/IP over FC would use a FC switch. The switch is determined by the layer 2 protocol that you are using as a switch is just a handy term for a "multiport layer 2 bridge."
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@scottalanmiller said in FibreChannel Switch Types:
Ah, I'm pretty sure that you are using the term "normal" to mean "Ethernet".
Yeah. A second word I could have chosen was standard... but even then, Ethernet and FC are two different standards, lol.
Thanks for straightening my head a bit.
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@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.
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@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.
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@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.
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IP is Layer 3
TCP is Layer 4
SSL is Layer 6
iSCSI is Layer 7 -
@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?
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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?
