Chapter 12: Managing Internet Services
Overview
Over the last few years, businesses have learned to turn what was once a loose allegiance of academic and military computer networks into a global tool for managing data, communication and commerce. Although the Internet is now widely used, it can be a blizzard of confusion for organizations that wish to exploit it to its full potential. An organization must consider how it accesses the Internet and which Internet service provider (ISP) can best help the enterprise meet its goals.
ISP Architectures
·
The
Internet backbone carriers offer wholesale Internet services to Internet service
providers.
·
Some service
providers offer private exchanges
·
The backbone
networks meet at network access points (NAP) or metropolitan area exchanges
(MAE).
·
There are
eleven MAEs in the United States.
·
There are
no “carrier-neutral exchange mechanisms” at the network access points.
·
Packets of
data often get to their destinations through circuitous routes.
·
Packets that
are traveling through nearby points are sometimes handed off to other carriers;
this is known as “Hot Potato” routing.
Internet Access Alternatives
Dial-up
·
Most residential
access to the Internet is through dial-up.
·
For simple
e-mail access and other low bandwidth needs where only a dial tone is needed,
dial-up offers the widest availability to the Internet.
·
Dial-up is
not desirable for businesses that must have an “always on” Internet connection.
·
The fastest
dial-up speeds currently available are around 53 Kb/s.
·
Dial-up offers
very good security.
Digital Subscriber Line
·
DSL is offered
by ILECs, CLECs and ISPs at a number of speeds.
·
ILECs offer
DSL with dial tone over a POTS (plain old telephone service) line.
·
DSL service
terminates in a DSL access multiplexer.
·
Voice and
Data are separated at the multiplexer.
Types
of Service:
·
ADSL Asymmetrical DSL = 1.5 to 9 Mb/s downstream @ 18,000 ft.
·
HDSL High-bit-rate digital subscriber line = 1.544 or 2.048
Mb/s downstream @ 15,000 ft.
·
SDSL Single-pair digital subscriber line = 1.544 or 2.048 Mb/s
downstream @ 10,000 ft.
·
VDSL Very-high-bit-rate digital subscriber line = 13 to 53 Mb/s
downstream @ 1,000 to 4,500 ft.
·
IDSL ISDN digital subscriber line = 144 Kb/s downstream @ 15,000
ft.
Cable Modems
·
Allows access
to the Internet through a shared coaxial cable
·
Data carried
through coaxial to the node at which point it is transferred to fiber optics
from the node to the head end.
·
Cable modems
are useless for the millions of businesses that do not have cable service.
Dedicated T-1 Access
·
T-1’s 1.536-Mb
channel is connected directly to the Internet service provider.
·
Unlike cable
Internet access, full T-1 is not a “community” shared line.
·
Using fractional
T-1 may not offer a significant cost savings over full T-1.
·
Most large
corporations access the Internet with dedicated T-1.
Frame Relay
·
DSL is being
used more and more as a frame relay access circuit.
·
Frame relay
is especially useful as an ISP access medium for those companies that already
have a frame relay network in place.
·
A permanent
virtual circuit (PVC) can be made for Internet traffic on an existing frame
relay network.
Wireless
·
Offered by
some ISPs over point-to-point microwave
·
Not very different
from point-to-point T-1
·
ISP provides
towers with line-of-site access to its customers.
Evaluating ISP Service
·
It is important
that an organization keeps track of outages and network speed so that it can
determine if the service level agreement is being adhered to.
·
ISPs that
can host from different locations around the country are most useful. If its
network is busy and mission-critical applications need to be delivered promptly,
then an ISP with only one host may be too slow for the organization.
·
ISPs with
extensive data caching capabilities are best suited to deliver frequently accessed
information from localized servers rather than transporting the data inefficiently
across the whole network.
ISP Selection Considerations
·
Before choosing
an ISP, a company must list what it wants most out of Internet service.
·
Most companies
list e-mail access at the top of their priority lists followed by full-time
dedicated Internet access.
·
To convey
a professional image, most companies choose not to use an ISPs domain name;
a domain name that identifies the company is registered instead.
E-Mail Services
·
Can you use
your own e-mail applications or are you limited to the ISPs proprietary e-mail
system?
·
Does the ISP
provide multiple mailboxes?
Security Provisions
·
Are firewall
services provided by the ISP?
·
Can the ISP
evaluate gaps in the security on the companies interface?
·
Is remote
access virtual private network (VPN) supported?
Web-Hosting Services
·
Does the ISP
offer collocation space for the company’s server?
·
Are web page
development and uploading assistance services offered?
·
Is Unix shell
access provided for telnet or FTP?
·
How much storage
space can the ISP provide?
·
Are mirroring
services provided?
·
Can a company
retrieve statistics regarding web site traffic from its ISP/ hosting service?
Customer Service
·
Is there 24/7
live customer support?
·
Does the ISP
own the customer service department or is it outsourced to another company?
·
Are the customer
service employees highly trained specialists or low wage “technicians” who may
not have the expertise to adequately service customer inquires?
Access Methods
·
Determine
all of the ways a company can access the Internet.
·
Dedicated
“always on” access vs. dial-up
·
Does the ISP
provide toll-free dial-up access?
·
What are the
highest possible upstream/downstream capabilities for each dial-up line?
·
What are the
crucial differences between DSL, cable and fixed-wireless access in terms of
cost and reliability?
Financial Stability
·
Is the ISP
an established leader in its industry or a struggling little start-up with little
hope of survival?
·
Even if the
ISP is a leader, is it in so much debt that any shortfall in revenue could seriously
jeopardize the amount of money spent on technical infrastructure or customer
support?