Volume 27 • No 03 • 2004
ISSN 0742-468X • Since 1978
On-line Since 2000
Internetworking:
Cabling Cisco Devicessubmitted bySemSim.com
Editor’s Note:This article is a bit of a departure from our other features, even those that branch away from GIS. But, as GIS gets increasingly web-enable, I believe it is important that users and developers understand a little bit about what goes on in a server room. So, here is an excellent article written by the folks at www.SemSim.com a site dedicated to Cisco certification.
In this article, you will learn about how Cisco devices are
connected to a network.
One of the most common cable endings for connecting Cisco devices
is UTP (Unshielded Twisted Pair). UTP is a cable that has four
pairs of wires twisted inside it to eliminate electrical
interference. UTP cables are connected using RJ-45 connectors
that have eight connector pins. The data equipment that is used
for internetworking is classified as Data Terminal Equipment (DTE
e.g. router interfaces) and Data Communication Equipment (DCE
e.g. A WAN connects DTEs through DCE network).
UTP cables are used in many configurations and for different
purposes, to form an internetwork including: Straight-through,
Crossover and Rollover. The applications of UTP include: Serial
transmission, Integrated Service Digital Network (ISDN)
connections, Console connections and Modular & fixed
interfaces. A discussion on these follows.
- Straight-Through Cable A straight-through cable is the standard network cable connection
and is used to connect the source and destination computers
through an internetworking device. Specifically, you can use it
to connect a host to a hub or switch
- Crossover Cable
In a crossover cable, the standard RJ-45 cable between the source
and destination computers is cross-connected. A crossover cable
can be used to connect: two computers, two hubs, hub to a switch,
cable modem to a router or two router interfaces.
- Rollover Cable
These Cisco proprietary cables used to connect to a router or
switch console port. In a rollover cable (8 pins), RJ-45
connectors are usually present at each end and are used to
connect router and computer ports. Pin 1 on one end of cable
connects to Pin 8 at the other end of the cable, similarly, Pin 2
connects Pin 7, and so on.
- Serial Transmission
All WANs use serial transmission, which can pass one bit at a
time over a single channel. Cisco provides a 60-pin serial
connector for one end of the cable while other end of the cable
may be EIA/TIA-232, V.35, EIA/TIA-449, X.21 or others.
- ISDN Connections
ISDN refers to a collection of standards that define a digital
architecture that can carry integrated voice and data, using the
public-switched network. ISDN BRI (Basic Rate Interface) is a two
64 kbps Bearer channels (2B) plus one 16 kbps Data channel (D)
service. ISDN BRI terminates at the customer premise with the U
interface.
- Console Connections
A console is a type of DTE through which commands are entered
into the host device. Most Cisco devices support the RJ-45
console connection. A rollover cable with an RJ-45 connector is
used to connect the PC or terminal to the console port of the
Cisco device.
- Modular and Fixed Interfaces
Unlike a fixed interface router, a modular interface router
allows you to add new interface cards without buying a new
router. In the fixed interface series, you refer to the
interfaces as: interface_type interface_number
For example, the first serial interface on a Cisco 2503 router
would be referred to as serial 0. Higher routers have modular
interfaces that allow you to change the interfaces as and when
required. Here, the interfaces are referred to as:
interface_type module_number/interface_number
To practice such commands you can download a free router
simulator from http://www.SemSim.com and proceed to the
Troubleshooting 1 exercise that configures ethernet 0 interface.
SemSim.com provides training for Cisco certification exams: CCIE,
CCNP, CCNA, CCDP, CCDA. It offers free learning resources and
router simulation labs. For more information and free trial of
the router simulator visit http://www.SemSim.com
Internetworking: Cabling Cisco Devices
Copyright© 2004 by http://www.SemSim.com
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