Diving into the ISO OSI Network Stack Discussion
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Original title as the thread started off as "FibreChannel Switch Types" but turned into a deep dive into the ISO OSI Networking stack.
@dafyre said in Networking clear up question:
Just like you have FC switches...Are they regular switches that are only used for FibreChannel or are they switches that can only connect to FibreChannel cards?
What?
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Example Fibre Channel Switch:
Can that only be used by connecting to a FibreChannel card in a server, or can it also be used for regular switching as well?
Edit: if this is going to derail the topic too much, fork it, please.
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@dafyre said in FibreChannel Switch Types:
Can that only be used by connecting to a FibreChannel card in a server, or can it also be used for regular switching as well?
What is regular switching? It's a FibreChannel switch, it connects to FibreChannel. Like any normal switch. I'm unclear what you are defining as "normal" here I think.
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@dafyre said in FibreChannel Switch Types:
Can that only be used by connecting to a FibreChannel card in a server,
Do you mean instead of FibreChannel cards in other switches?
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I am trying to determine where the cohorts in the other thread were coming up with the term "iSCSI switch".
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@dafyre said in FibreChannel Switch Types:
I am trying to determine where the cohorts in the other thread were coming up with the term "iSCSI switch".
Well you can have a switch dedicated to iSCSI or as is used in many cases, you need one that is faster or handles iSCSI's needs better. You don't just use a normal switch for your SAN. But iSCSI is about iSCSI. This thread is about Fibre Channel. They two are competitors in the "use case" world and unrelated on the network.
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Fibre Channel is Layer 2, just like Ethernet. So of course you can layer TCP/IP on top of it, which is called IPFC, and then put iSCSI on top of TCP/IP. FC just replaces Ethernet in your ISO OSI stack. No one would ever do this, but you can.
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@dafyre said in FibreChannel Switch Types:
... or can it also be used for regular switching as well?
This is the bit that I don't understand. I'm only aware of switches being switches. What defines a normal switch differently from the "connects servers with FC cards" that you describe, because that sounds like normal switching to me.
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@scottalanmiller said in FibreChannel Switch Types:
@dafyre said in FibreChannel Switch Types:
I am trying to determine where the cohorts in the other thread were coming up with the term "iSCSI switch".
Well you can have a switch dedicated to iSCSI or as is used in many cases, you need one that is faster or handles iSCSI's needs better. You don't just use a normal switch for your SAN. But iSCSI is about iSCSI. This thread is about Fibre Channel. They two are competitors in the "use case" world and unrelated on the network.
That's my point... with iSCSI you can use a regular old fashioned Ethernet switch.
In general, with FibreChannel devices would use a switch made and built specifically for FibreChannel... Right? (Except for FCoE)
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@dafyre said in FibreChannel Switch Types:
That's my point... with iSCSI you can use a regular old fashioned Ethernet switch.
Ah, I'm pretty sure that you are using the term "normal" to mean "Ethernet". That's a very confusing way to use it. Ethernet and FiberChannel are both full fledged Layer 2 networking technologies. They are direct competitors and share nothing at all. A FibreChannel switch is exactly like an Ethernet switch, but switches FB not Ethernet. One is not more normal than the other. Ethernet is more popular today than FC, but that's all.
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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.
