Chapter 7: Elements of Network Connectivity
Lesson 1: Connectivity Devices
Exercise 7.1: Troubleshooting Problem
What can you do to start the troubleshooting process?
The first step is to carry out a simple test on your hardware.
Much complex equipment is microprocessor-driven hardware with built-in software. Simply by
following the shut-down and restart procedure for these devices (sometimes this is a simple
on-off switch) you can restart the equipment and restore it to proper functioning again.
If shutting down and restarting the entire system does not get the
system running, call the service provider and ask it to test the T1 line and verify that it is
If neither of those two options solve the problem, you will need
to contact your vendor and ask for help in troubleshooting the WAN equipment you have. Very few
experienced systems engineers have the expertise needed to successfully troubleshoot this kind
Lesson 2: Connection Services
Exercise 7.2: Case Study Problem
- Identify at least two network items in each branch-office network site that
Each site could upgrade to include the following:
New cabling: from 10 Mbps Ethernet to 100Mbp Category 5.
New cards: from 10 Mbps Ethernet to 100Base.
New architecture: from linear bus to star bus (100BaseT) with hubs.
- The separate branch offices need to maintain voice and data communications with each
other. Which type of WAN connection (link) might you use to connect the three sites to each
Use a T1 link, because it can carry voice and data simultaneously. (T1 is available through
a carrier such as AT&T, MCI, Sprint, and others.) Note that E1 is a rough equivalent of T1
and is used outside the U.S.
- Which type of device could be used to collect the multiple signals from voice and data
and put them on the same WAN link?
A multiplexer mixes both types of signals and places them on the same WAN link.
- Which type of connectivity device should be used to connect the LAN to the multiple
paths in the WAN illustrated in the diagram above?
A router is the ideal device to connect the LAN to the multiple WAN paths. Routers can use
multiple paths and can use best-path algorithms to determine the best path for each
- An external modem is a small box that is connected to the computer by a
______________ cable running from the computer's port to the modem's computer-cable
- The modem at the _______________ end converts digital signals into analog signals.
- Baud rate refers to the speed of oscillation of the _____________ _____________ on which
a bit of data is carried.
- The bps can be greater than the __________ rate.
- Asynchronous transmission occurs over __________________ __________.
- The Microcom Network Protocol (MNP) is a standard for asynchronous __________ -
- In asynchronous communication, it is possible to double throughput by using
____________________ without having to pay for a faster channel speed.
- Synchronous communication relies on a _____________ scheme coordinated between two
- More advanced, complex repeaters can act as multiport _________ to connect different
types of media.
- Repeaters do not have a __________________ function and so will pass along all data
from one segment to the next.
- A repeater takes a weak signal and ______________________ it.
- A repeater functions at the ________________ layer of the OSI reference model.
- If the volume of traffic from one or two computers or a single department is flooding
the network with data and slowing down the entire operation, a ________________ could isolate
those computers or that department.
- The bridge builds a routing table based on the ________________ addresses of computers
that have sent traffic through the bridge.
- Bridges work at the OSI __________ - _________ layer and, specifically, the
_____________ ______________ ________________ sublayer.
data-link, Media Access Control
- Bridges are often used in large networks that have widely dispersed segments joined by
- Under spanning tree algorithm (STA), software can sense the existence of more than one
_____________, determine which would be the most efficient, and then configure the bridge to
use that one.
- Bridges connect two segments and regenerate the signal at the ______________
- Routers work at the _________________ layer of the OSI reference model.
- Because they must perform complex functions on each packet, routers are
_________________ than most bridges.
- Routers do not look at the destination node address; they look only at the _________________ address.
- Unlike bridges, routers can accommodate multiple active ____________ between LAN
segments and choose among them.
- The two major types of routers are ____________ and __________________.
- A brouter will ______________ nonroutable protocols.
- Most often, gateways are dedicated ________________ on a network.
- The gateway takes the data from one environment, strips it, and repackages it in the
__________________ ___________ from the destination system.
- Gateways are ___________ specific, which means that they are dedicated to a particular
type of transfer.
- With the exception of ADSL, public telephone lines require users to _______________
make a connection for each communication session.
- The three factors an administrator must take into account when considering how best to
implement communication between two modems are __________________, _______________, and
throughput, distance, cost
- Leased lines provide ___________________ connections that do not use a series of
switches to complete the connection.
- A good remote-access option that offers stable lines for companies that are constantly
communicating between networks is to use ______________ lines.
- The ____________ - _____ - _____________ _____________________ _
__________________ allows a remote client to establish a secure connection to the corporate LAN
over the Internet and RAS.
Point-to-Point Tunneling Protocol
- Because the PSTN was designed primarily for voice, _________ - _____ lines do not have
the consistent quality required for secure data communications.
- A dedicated line is _______________ and more _______________ than a dial-up
- One advantage that dedicated lines offer over dial-up lines is that the service company
implements ____________ _______________________ to improve communication, thereby ensuring line
- Digital lines provide ______________ - ___ - _____________ synchronous
- Because DDS uses ________________ communication, it does not require modems.
- T1 uses a technology called ____________________ in which several signals from
different sources are collected into a component and fed into one cable for transmission.
- T1 can accommodate 24 ____________________ data transmissions over each two-wire
- Subscribers who do not need or cannot afford the bandwidth of an entire T1 line can
subscribe to one or more T1 _________________.
- With packet switching, the data is broken down into packets, and each packet is tagged
with a _____________________ _________________ and other information.
- At the destination, the packets are _____________________ into the original
- Two packets from the original data package can arrive out of sequence because they
followed different ____________ to reach the same destination.
- Virtual circuits are composed of a series of ________________ connections between the
sending computer and the receiving computer.
- Because of its extensive ____________ _______________, X.25 can appear to be slow.
- X.25 was originally developed for the __________________ environment.
- Frame-relay data travels from a network over a ________________ _________________ line
to a data switch and into the frame-relay network.
- Frame-relay networks can also provide subscribers with __________________ as needed,
which lets the customer make nearly any type of transmission.
- Frame-relay networks are faster at performing basic ________________ -
__________________ operations than are X.25 networks.
- ATM is an advanced implementation of ______________ ______________ that provides
high-speed data transmission rates.
- ATM transmits data in 53-byte _________ rather than variable-length frames.
- ATM switches are multiport devices that can act as either ____________ to forward data
from one computer to another within a network or _________________ to forward data at high
speeds to remote networks.
- ATM uses switches as ___________________________ to permit several computers to put
data on a network simultaneously.
- ATM can be used with existing _____________ designed for other communications
- Basic Rate ISDN divides its available ________________ into three data channels.
- FDDI is a specification that describes a high-speed (100 Mbps) token-ring LAN that uses
___________ - __________ media.
- FDDI can be used for __________________ networks to which other, low-capacity LANs can connect.
- A computer on an FDDI network can transmit as many frames as it can produce within a
predetermined time before letting the ____________ go.
- Traffic in an FDDI network consists of two similar streams flowing in opposite
directions around two counter-rotating ______________.
- An advantage of the dual-ring topology is ______________________.
- To isolate serious failures in the ring, FDDI uses a system called _________________ in
which a computer that detects a fault sends a signal onto the network.