What is the difference between Straight-through, Crossover, and Rollover cables?
Straight-through (same pinout both ends) connects unlike devices like PC-to-switch; crossover (T568A on one end, T568B on the other) connects like devices; rollover is Cisco's console-config cable.
* Straight-through keeps the same pinout for unlike devices; crossover swaps A/B for like devices; rollover is Cisco's console-config cable. *
| Cable Type | Standard | Application |
|---|---|---|
| Straight-through | Both ends T568A or both ends T568B | Host to Network Device (PC to switch, router to switch) |
| Crossover | One end T568A, other end T568B | Like devices: Host-to-Host, Switch-to-Switch, Router-to-Router |
| Rollover | Cisco proprietary | Host serial port to Console Port for device configuration |
Note: Crossover is considered legacy because most modern NICs use Auto-MDIX to automatically detect and adjust for cable type.
Go deeper:
-
Straight-through, crossover & rollover pinouts — Computer Cable Store — all three wiring schemes with the pin maps spelled out. -
Ethernet over twisted pair — Wikipedia — how a T568A/T568B end-mismatch makes a crossover, and why Auto-MDIX makes it legacy.