Cabling/port question
CDelapena2
Member Posts: 15 ■□□□□□□□□□
in CCNA & CCENT
Hello all,
I understand when you connect a router fastethernet port to a switch fastethernet port it has to be done with a straight through cable because they are not 'like' devices. This is because they transmit and receive on different pins. But they're both switch ports aren't they? So why the whole different pins deal if they're the exact same port types and what about other devices like modems, riverbeds and fortigate devices that also have switch ports. How do you what pins they transmit on. I was told earlier that the reason why is because router switch ports are layer 3 meaning they can be assigned IP addresses and that the ports on switches don't do anything at layer 3 but on a 3550 it is possible to implement the no switchport command which now makes it a layer 3 port just like the router yet you still need a straight through to connect it to the router. Are these not identical switchports with exact same capabilities? If so why do they transmit on different pins? Can someone shed some light on why this is?
Thanks for your input and time.
I understand when you connect a router fastethernet port to a switch fastethernet port it has to be done with a straight through cable because they are not 'like' devices. This is because they transmit and receive on different pins. But they're both switch ports aren't they? So why the whole different pins deal if they're the exact same port types and what about other devices like modems, riverbeds and fortigate devices that also have switch ports. How do you what pins they transmit on. I was told earlier that the reason why is because router switch ports are layer 3 meaning they can be assigned IP addresses and that the ports on switches don't do anything at layer 3 but on a 3550 it is possible to implement the no switchport command which now makes it a layer 3 port just like the router yet you still need a straight through to connect it to the router. Are these not identical switchports with exact same capabilities? If so why do they transmit on different pins? Can someone shed some light on why this is?
Thanks for your input and time.
Comments
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CDelapena2
Member Posts: 15 ■□□□□□□□□□
I'm aware that MIDX is now available making the whole straight through/cross over problem nonexistant but Here's a question: is there any difference at all between a 3550 switchport with "no switchport" command on it and a router's fastethernet port? At this point they're both in the same layer of the OSI model but you would still need a straight-through to make them talk. So would the only difference between them be the pins they transmit on?
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boobobobobob
Member Posts: 118
The no switchport command has nothing to do with changing the transmit and recieve pins on a switch. The command tells the switch that the specific interface you typed to command on is no longer layer 2 ie: does not participate in spanning-tree and doesn't have a VLAN assigned to it. Layer 3 interfaces can also have IP addresses assigned to it and can participate in routing updates.
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pamccabe
Member Posts: 315 ■■■□□□□□□□
My guess, and that is all this is, is that it has to do with the hardware, specifically the ASICs inside the routers and switches.
