Network cables confusion?
Shy87
Member Posts: 21 ■□□□□□□□□□
in CCNA & CCENT
was going through cabling standards like...
devices of same time: crossover
different types: straigh through
pc to router: rollover
pc (NIC) to router: crossover
pc to switch (in console connection): Rollover
Lol actually I have been through so many examples and there are so many variations. Can someone tell me from where I can get the complete lists for different types of connections and cables.
The more examples I am doing the more I am getting confused. Can some one help in understanding this.....
devices of same time: crossover
different types: straigh through
pc to router: rollover
pc (NIC) to router: crossover
pc to switch (in console connection): Rollover
Lol actually I have been through so many examples and there are so many variations. Can someone tell me from where I can get the complete lists for different types of connections and cables.
The more examples I am doing the more I am getting confused. Can some one help in understanding this.....
Comments
And you may want to revisit that PC NIC to Router type of cable.
And to really screw with your head, if any of the gear involved uses autoMDIX, then it doesn't matter whether it's a straight through or rollover hehe
I got CCENT exam so I cant remove rollover cable from my vocabulary and what is autoMDIX bla bla blaaa........
You mean straight through or crossover cable?
-Bender
Ok.
The following use cross-over
switch <-> Switch (dce to dce)
switch<-> Hub
PC <-> PC (dte to dte)
PC <-> Router (dte to dte)
Router<->Router (via ethernet)
Straight-through
Switch<->PC
Switch<->Router
ICND2 - Passed 9/03/10
Studying CCNA:S
Hah, yes, I do mean crossover instead of rollover.
So much for me not being susceptible to the power of suggestion
A rollover cable is for console connections, it doesn't transfer data. Period. You connect one end to the network device, you connect one end to a serial port on something that's going to be interfacing with that hardware (usually a laptop or desktop), and that's it. You use rollover cables in order to manage the network equipment.
When it comes to data transfer, it's pretty simple. Do the devices reside on the same layer? If so, you need to a crossover cable. If they do not, you use a straight through cable.
Learning which device is properly assigned to each layer is an exercise I leave to the petitioner
hehe, yea I figured as much, couldn't help pointing it out though
-Bender
I agree, perfectly appropriate, IMHO, especially given that I was trying to educate. Passing along the wrong information, even something so innocuous, is not helpful for the new guy.
typically NIC, router send on 1,2 and receive on 3,6
switch and hub receive on 1,2 and send on 3,6
So NIC -> switch is a straight through cable because the nic is sending on 1,2 and the wires will connect to the switch which is receiving on 1,2.
A switch to switch connection ( I think trunk connection ) will need a crossover cable because you can't send on 3,6 which connects to 3,6 on the other switch which is also trying to send through that same wire. You need to cross the wires of a regular straight through cable so that pins 1,2 will connect to 3,6.
MDI - Medium Dependent Interface
MDIX - Medium Dependent Interface Crossover (transmit/receive internally cross)
Nope, I have needed to make a gigabit cross-over cable a few times before.
No. A Catalyst 3550 for example doesn't support AutoMDIX.
Ok, this answers my questions on why I'm not able to ping a Cisco 2900 Switch from my computer.
I'm connected directly from a rollover cable and was able to assign an ip address to the vlan (yup, I'm new at this).
However I can't ping back to my linux computer:
"Its easier to deceive the masses then to convince the masses that they have been deceived."
-unknown
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Forsaken_GA, what is the best way then to refer to a rollover cable?
Both Cisco books by Lammle and Odom refer to this cable with this name.
"Its easier to deceive the masses then to convince the masses that they have been deceived."
-unknown
It's not about calling it something different, its about not viewing it as integral to a running network. It is integral to managing one and creating one, but it isn't required for packets to flow between destinations.
CCIE Progress - Hours reading - 15, hours labbing - 1
Basically, once your network is up and running the rollover cables wont be doing anything but sitting there for future use if you need console access to configure a router.
as far as crossover and straight-through, think of it this way. There are 8 pins on an ethernet cable. PCs transmit on pin 1 and 2, and recieve on 3 and 6. This means that what gets sent on 1 and 2 needs to arrive on 3 and 6. A crossover cable does this for you, crossing the pins so that 1 and 2 on one side are connected to 3 and 6 on the other, and vice versa.
A straighthrough cable is the same on both ends, meaning 1 and 2 are the same on both. Seems like it would have no use, but the thing is that hubs and switches both perform the crossover internally, meaning that you want straight-through cables when connecting to a swtich or a hub because they do the crossover for you.
mdi/mdix basically means that the NIC can dynamically figure out if what pins it is recieving data on and alter its operation to accomodate, meaning you can use crossover or straightthrough with no consequence if your NIC supports it.
Not exactly.
MDI and MDI-X are two standards describing which pairs that a device will transmit and receive on. What you are referring to is "auto MDIX."
Close enough only works in horseshoes and hand grenades. I'm sure I speak for everyone here when I say we'd rather know for sure and actually pass the exam.
Straightthrough can also be used for connecting 2 switches
conditions one side must be connected with uplink ports.Rember only one side
This has nothing to do with one being an uplink. The uplink port would need some form of AutoMDIX to work like this. Given most uplinks are gigabit, that would explain why it works.
CCIE Progress - Hours reading - 15, hours labbing - 1
Switches and hubs do this crossover internally. Routers and hosts do not.
The crossover needs to be done at some point, whether by the wire or a switch or a hub.
e.g
Layer 3: Router
Layer 2: Switch
Layer 1: P.C, Hub, Repeater etc
If the devices you are connecting share the same layer, e.g Router to Router (L3 - L3) or there is 2 layers difference, e.g P.C - Router then you use a crossover.
If there is only 1 layer between the devices, e.g Switch - Router then its a straight though cable.
e.g P.C - Router: 2 layers = Cross over.
Switch - Switch: Same Layer = Cross over.
P.C - Switch: 1 layer = Straight through.
https://learningnetwork.cisco.com/servlet/JiveServlet/showImage/2-81041-14675/crossed-or-not-crossed.jpg
That is correct, a console cable (Rollover) is only used to transmit keystrokes and receive output information (so you can see what your typing, status and debug messages etc.).
You would need to hook your computer into the switch and assign it an IP in the same subnet as your vlan. I was always taught when troubleshooting start at layer 1 and work your way up, its a good habit to get into.
I think “very senior” gets stuck in there because the last six yahoos that applied for the position couldn’t tell a packet from a Snickers bar.
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