.Which type of Category 5 unshielded twisted-pair (UTP) cable is used to work as a trunk between two switches?
A. RJ-45 straight-through
B. RJ-41 crossover
C. RJ-11 straight-through
D. RJ-45 crossover
Correct Answer: D
An RJ-45 crossover cable connects two switches. To act as a trunk a trunking protocol such as ISL or 802.1q must be configured on the link. . A trunk is a connection between two switches that is used to carry traffic from multiple VLANs.
In general, the rule to follow when choosing between a straight-through and a crossover cable is:
– When connecting like devices (i.e. router to router, switch to switch), use a crossover cable.
– When connecting dissimilar devices (i.e. switch to router), use a straight-through cable.
The one exception to this rule is when connecting a computer NIC to a router, in which case a crossover cable is used. Be aware, however, that many devices, including network cards in computers, now have the ability to sense automatically when they are connected to a like device and adapt to the connection, making crossover cables unnecessary in those situations.
You should not choose an RJ-45 straight-through cable. The cable type to be used depends on the circuit connection of the hardware. To connect two switches, a crossover cable is required. The difference between a straight-through cable and a crossover cable lies in the location of the wire termination on the two ends of an RJ-45 cable. If the UTP cable wire connects Pin 1 of one side to Pin 1 of other side and Pin 2 to 2 through all eight pins of the RJ 45 connector, the cable is said to be straight-through. On the other hand, if Pin 1 of one side of an RJ-45 cable connects to Pin 3 of the other end, and Pin 2 connects to Pin 6 of the other end, it is known as a crossover cable. A straight-through cable is used to connect a computer’s network interface card (NIC) to a hub or switch.
You should not choose an RJ-41 crossover cable. RJ-41 is a single-line universal data jack normally associated with fixed-loss loop (FLL) or programmed (P) modems. It is not used between switches.
You should not choose an RJ-11 straight-through cable type. RJ-11 UTP cables have four pins and are used to connect voice instruments. RJ-11 UTP cables are not intended for connecting computers and transferring data. They are commonly used for telephones and modems.
Note: Cisco switches have an auto-mdix feature that notices when the wrong cabling pinouts are used, and readjusts the switch’s logic so that the cable will work.
Select the appropriate cabling type based on implementation requirements
Cisco Documentation > Internetwork Design Guide > Designing Switched LAN Internetworks > Technologies for Building Switched LAN Internetworks
Cisco > Troubleshooting Technotes > Cisco 7000 Series Routers > Cabling Guide for Console and AUX Ports > Types of RJ-45 Cabling