Everyone said router need a straight-through cable to connect to switch. Why?
I can't see any spec like that on the standard. Is it a habit?
In networking world, devices are identified as Terminal equipments & communications equipments.
Terminal equipments: includes desktops & routers
communication euipments: switches
Similar devices are connected via cross cable & non-similar devices are connected with straight.
Its a standard.
DTE to DTE is crossed cable
DCE to DCE is crossed cable
DTE to DCE is straight cable
Same device is crossed, different device is straight.
But now, new devices support Auto-MDIX. Doesn't matter which cable you use. But sometimes, for troubleshooting sanity, use the standard.