Which cable to use ? 
      one should ensure proper cabling of devices while wiring devices together.the following table
shows which cable should be used when wiring the devices together.


 IF DEVICE A has a:          IF DEVICE B has a:          THEN use this cable


computer com port                console of router/switch           rollover

computer NIC                       switch                                  straight-through

computer NIC                        computer NIC                       crossover

 switch port                          router;s ethernet port               straight-through

switch port                             switch port                             crossover

router's Ethernet port               routee;s ethernet port               crossover

computer NIC                        router;s ethernet port                crossover

router;s serial port                   router;s serial port                   cisco serial DCE/DTE cable



                Pinouts for different Ethernet cables

  straight-through cables   crossover cable             Rollover

     pin 1-pin 1                                   pin 1-pin 3                              pin 1-pin 8
   
      pin 2-pin 2                                    pin 2-pin 6                              pin 2-pin 7
 
      pin 3-pin 3                                    pin 3-pin 1                              pin 3-pin 6
   
      pin 4-pin 4                                    pin 4-pin 4                               pin 4-pin 5

      pin 5-pin 5                                    pin 5-pin 5                               pin 5-pin 4

      pin 6-pin 6                                     pin 6-pin 2                               pin 6-pin 3

      pin 7-pin 7                                     pin 7-pin 7                               pin 7-pin 2

      pin 8-pin8                                      pin 8-pin 8                               pin 8-pin 1

Most laptops available today come equipped with usb  ports, not serial ports. for these laptops,
you need a USB-to-serial connecter to access the device ,as shown in figure 1-4

Ethernet cable types

A straight-through cable or crossover cable is a type of ethernet cable used to connect computing devices together directly.

A rollover cable(also known as cisco console cable or a yost cable) is a type of cable that is often used to connect a computer terminal to a router,s console port.

figure1-3 shows examples of the male DTE and the female DEC ends that are on the other side ofa serial or smart serial cable.


                             figure 1-3 v.35 DTE and DCE cables

figure1-2 shows the newer smart serial end of a serial cable that connects to a smarts serial port on your router,smart serial ports are found on modular routers, such as the Isr (800) series,or on older modular routers such as the 1700 or 2600 series,

                                figure 1-2 smart serial cable (1700,1800,2600,2800)

Serial cable types

figure 1-1 shows the DB-60 end of a serial cable that connects to a 2500 series router.

                                                figure 1-1 serial cable (2500)