Part 1
1. What is the basic structure of the Internet?
There are 10 Network Access Points (NAPs) around the country. Also
known as gigapops because they operate at speed exceeding 10Gbps. These NAPs
provide multi-level access to the Internet for regional and local networks in their part
of the county. The fundamental structure of the Internet takes the form of a massive
fully meshed network.
2. Explain how the Internet is a network of networks.
The internet consists of many other networks connecting via various
NAPs and ISPs around the world. Some is having a limited number of hops to
connect while others have as many as 15-17 hops.
3. Compare and contrast an NAP and a MAE.
NAPs emerged on the scene as the former NSFnet began to dissolve and
lose its funding and the commercial sector continued to build in to the internet.
Initially there were 4 NAPs around the country and this number has grown to 10. As
the number of ISPs grew, a new form of network access point called a metropolitan
area exchange (MAE) emerged. MAEs are smaller versions of NAPs and typically
link a set of regional ISPs whose networks come together in major cities. Today
there are about 50 MAEs in the United States.
4. What is a POP?
A POP is short for Point-of-Presence. It is a term that represents the
physical presence of a specific Network Provider in a given geographical area.
5. Explain one reason why you might experience long response times in getting a
Web page from a server in your own city.
If the traffic must travel through multiple hops supported by an ISP, MAE or
NAP that routes its traffic over its own physical network transport and that transport
is structured to take the traffic out of the local area before it can reach the ISP’s
network which is supporting the server, there will be multiple hops and thus much
more overhead involved with the transmission.
6. What types of circuits are commonly used to build the Internet today? What types
of circuits are commonly used to build Internet 2?
Today SONET based transports and ATM are used to build out the Internet
infrastructure. With Internet 2 this trend will continue and will include the introduction
of OC-768 and larger transports as well.
7. Compare and contrast cable modem and DSL.
Both are capable of asymmetric and symmetric transmission. Both require
Ethernet at the core user end. They differ in the range of transmission speeds Xdsl
ranges from 64Kbps up to app. 52Mbps.
Cable modems range from 256Kbps up to 55Mbps. DSL runs over plain old
telephone lines, whereas cable modems require a hybrid coax-fiber optic media.
8. Explain how DSL works.
DSL uses the existing local loop cable, but places different equipment on
the customer premises (i.e., the home or office) and in the telephone company end
office. The equipment that is installed at the customer location is called the customer
premises equipment. The CPE can include a line splitter that is used to separate the
traditional voice telephone transmission from the data transmissions. The line splitter
directs the telephone signals into the normal telephone system, so that if the DSL
equipment fails, voice communications are unaffected. The line splitter also directs
the data transmission into a DSL modem, which is sometimes also called a DSL
router. The DSL modem produces Ethernet 10BaseT packets so it can be connected
directly into a computer or to a hub so that it can serve the needs of a small network.
13. Explain how a cable modem works.
Cable Modems take the signal coming from the NIC card on the PC and
modulate it over typically a coax house cable. The coax cable connects to the fiber optic
cable system that supports all of the premises in a given area. All of the fiber cables in a
given local area terminate into what is called a ‘head end’, which then connects into a
Cabel Modem Termination Service (CMTS). The CMTS connects into a
10/100/1000Mbps Ethernet network operated by the cable company. This Ethernet
network can have one or more gateways out to the Internet.
15. Which is better, cable modem or DSL? Explain.
Most analysts in this regard would argue that DSL has the stronger chance
of emerging as the better. This is because DSL uses a star configuration back to the
CO. Cable Modems employ a hybrid fiber-coax architecture that is ring based.
16. Explain how one type of fixed wireless called wireless DSL works.
The most popular type of fixed wireless is wireless DSL, which requires a line
of sight between the communicating transmitters. For this reason it has limited
application, because it requires tall buildings or towers to be effective. The most
common use today is to provide internet access to multi-tenant buildings such as
remote office buildings, apartment buildings and hotels. Transmitters are used to
connect the building to the ISP and DSL is used inside the building to connect to the
wireless transceiver.
17. Compare and contrast mobile wireless and fixed wireless.
Mobile wireless technologies enable users to access the Internet from any
location where there is mobile wireless service. Widespread mobile wireless Internet
access is probably the next major change in the networking. Mobile wireless Internet
access technologies exist today (e.g., cell phone connections), but most are slow
compared to wired access, whether DSL, cable modem, or simply a dial-up modem.
The most popular type of fixed wireless is wireless DSL, which requires a line of sight
between the communicating transmitters. For this reason it has limited application,
because it requires tall buildings or towers to be effective. The most common use today
is to provide Internet access to multi-tenant buildings such as remote office buildings,
apartment buildings and hotels. Transmitters are used to connect the building to the ISP
and DSL is used inside the building to connect to the wireless transceiver.
18. Explain how WAP works.
Wireless Application Protocol (WAP) provides a set of application and
network protocols called the Wireless Application Environment (WAE) to support mobile
wireless Internet applications. WAP is designed to enable the use of normal Web
application on computer and devices with small display screen operating over low
speed wireless connections.
21. Explain how Ethernet to the home works.
If we were to start over and design an entirely new network for Internet
access from home, we would probably start with Ethernet because of its low cost and
popularity in organizational LANs. Using common protocols would make the whole task
of networking much simpler for everyone involved.
Pioneered by yipes.com, such an approach is exactly what is being used
in several major U.S. cities. With this approach, the common carrier installs a TCP/IP
router with 10Base-T or 100Base-T connections into the customer’s network and an
Ethernet fiber on the other. The IP/Ethernet traffic moves from the router into the
carrier’s Ethernet MAN and then onto the Internet.
25. What is Internet 2?
There are many different organizations currently working on the next
generation of the Internet, including the Abilene network. Vbns, and CA*net. Although
each is working in a slightly different fashion, all join together with one another and parts
of the regular Internet at gigapops (gigabit points of presence).