Welcome to Lesson 13 - Advanced WAN Technologies (Chapter 12)
Wide area networking technologies are often very expensive and most companies
rely on third-party vendors, such as the phone company, to provide these services.
POTS/PSTN networks were originally intended to carry voice traffic only. Consequently,
data communication can be a hit-and-miss proposition. PSTN may not be completely
reliable because it is a switched network. Each time a call is placed, a different
path is taken through the network. This means that the quality of each call
is inconsistent. A line can be leased which ensures the quality of the line
and provides for easy troubleshooting in the event that something goes wrong.
However, this configuration is much more costly than regular dial-on-demand
phone lines.
The biggest benefit of digital service is that it is nearly 100% error-free.
DDS circuits guarantee line quality and transmission rates.
CSU/DSUs perform similar functions
to modems, but for digital, rather than analog, transmission.
T1 circuits is one of the most popular WAN solutions today. It provides 1.544 Mbps transmission at a fairly reasonable price. When lower bandwidth is acceptable, a portion of a T1 can be used. Multiplexing allows companies to use a single T1 and still provide separate channels for many different connections. Each T1 channels supports 64 Kbps transmission. Channels are then combined to for T1s, T3s, etc. T3 and T4 cannot be run over standard copper cable, but require fiber-optic.
Switched 56K lines provide digital
communication on-demand and are charged according to the number of minutes used.
That because DSL and cable modems are readily available, switched 56K lines
are not used very often.
Packet-switching networks do not rely on a single pathway. In fact, two packets may not even take the same path through the network. Because the packets are small, their transmission is very fast. If a packet is lost or damaged, the time lost in retransmission is minimal.
Virtual private networks are becoming
more and more popular as systems are able to support VPN connections over the
Internet. Windows NT 4.0, Windows 98, and Windows 95 support PPTP which can
be used to create VPNs. Windows 2000 supports a newer, more secure VPN protocol
called Layer 2 Tunneling Protocol (L2TP).
1. What PSTN line type is sufficient
for most dial-up data connections?
Think about it, then click HERE
to see the answer.
2. Which device server as the attach point for a DDS circuit?
Think about it, then click HERE
to see the answer.
3. What is the bandwidth of a single T1 channel?
Think about it, then click HERE
to see the answer.
4. How do VPNs provide truly secure transmission over the Internet?
Think about it, then click HERE
to see the answer.
Do this quiz after you have completed the lesson:
John’s company needs to connect its 15 offices in the U.S. However, there is concern about cost and they would like to get the most from their money. Because of the centralized database they will be using, transmission must be over 1 Mbps. What type of WAN solution should John choose?
Think about it, then click HERE to see the answer.
Charlie’s network consists of four buildings on a campus in suburban Philadelphia. As a company, they have decided to be on the cutting edge of technology and want to install a new inter-building network which will support video and voice, as well as data at speeds up to 1 Gbps. Which WAN solution should Charlie use?
Think about it, then click HERE to see the answer.
Remember to keep up with your on-line lessons and quizzes!
mdm