How Does the Internet Work?
`
`© 2002 Rus Shuler @ Pomeroy IT Solutions, all rights reserved
`
`Contents
`
`1. Introduction
`2. Where to Begin? Internet Addresses
`3. Protocol Stacks and Packets
`4. Networking Infrastructure
`5. Internet Infrastructure
`6. The Internet Routing Hierarchy
`7. Domain Names and Address Resolution
`8. Internet Protocols Revisited
`9. Application Protocols: HTTP and the World Wide Web
`10. Application Protocols: SMTP and Electronic Mail
`11. Transmission Control Protocol
`12. Internet Protocol
`13. Wrap Up
`14. Resources
`15. Bibliography
`Introduction
`
`How does the Internet work? Good question! The Internet's growth has become explosive and it seems
`impossible to escape the bombardment of www.com's seen constantly on television, heard on radio, and
`seen in magazines. Because the Internet has become such a large part of our lives, a good understanding
`is needed to use this new tool most effectively.
`
`This whitepaper explains the underlying infrastructure and technologies that make the Internet work. It
`does not go into great depth, but covers enough of each area to give a basic understanding of the
`concepts involved. For any unanswered questions, a list of resources is provided at the end of the paper.
`Any comments, suggestions, questions, etc. are encouraged and may be directed to the author at
`rshuler@gobcg.com.
`Where to Begin? Internet Addresses
`
`Because the Internet is a global network of computers each computer connected to the Internet must
`have a unique address. Internet addresses are in the form nnn.nnn.nnn.nnn where nnn must be a
`number from 0 - 255. This address is known as an IP address. (IP stands for Internet Protocol; more on
`this later.)
`
`The picture below illustrates two computers connected to the Internet; your computer with IP address
`1.2.3.4 and another computer with IP address 5.6.7.8. The Internet is represented as an abstract object in-
`between. (As this paper progresses, the Internet portion of Diagram 1 will be explained and redrawn
`several times as the details of the Internet are exposed.)
`
`Dropbox Exhibit 1021 - Page 1
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`

`

`Diagram 1
`
`If you connect to the Internet through an Internet Service Provider (ISP), you are usually assigned a
`temporary IP address for the duration of your dial-in session. If you connect to the Internet from a local
`area network (LAN) your computer might have a permanent IP address or it might obtain a temporary one
`from a DHCP (Dynamic Host Configuration Protocol) server. In any case, if you are connected to the
`Internet, your computer has a unique IP address.
`
`Check It Out - The Ping Program
`
`If you're using Microsoft Windows or a flavor of Unix and have a connection to the Internet, there is a
`handy program to see if a computer on the Internet is alive. It's called ping, probably after the sound
`made by older submarine sonar systems.1 If you are using Windows, start a command prompt window.
`If you're using a flavor of Unix, get to a command prompt. Type ping www.yahoo.com. The ping
`program will send a 'ping' (actually an ICMP (Internet Control Message Protocol) echo request
`message) to the named computer. The pinged computer will respond with a reply. The ping program
`will count the time expired until the reply comes back (if it does). Also, if you enter a domain name (i.e.
`www.yahoo.com) instead of an IP address, ping will resolve the domain name and display the
`computer's IP address. More on domain names and address resolution later.
`
`Protocol Stacks and Packets
`
`So your computer is connected to the Internet and has a unique address. How does it 'talk' to other
`computers connected to the Internet? An example should serve here: Let's say your IP address is 1.2.3.4
`and you want to send a message to the computer 5.6.7.8. The message you want to send is "Hello
`computer 5.6.7.8!". Obviously, the message must be transmitted over whatever kind of wire connects your
`computer to the Internet. Let's say you've dialed into your ISP from home and the message must be
`transmitted over the phone line. Therefore the message must be translated from alphabetic text into
`electronic signals, transmitted over the Internet, then translated back into alphabetic text. How is this
`accomplished? Through the use of a protocol stack. Every computer needs one to communicate on the
`Internet and it is usually built into the computer's operating system (i.e. Windows, Unix, etc.). The protocol
`stack used on the Internet is refered to as the TCP/IP protocol stack because of the two major
`communication protocols used. The TCP/IP stack looks like this:
`
`Protocol Layer
`
`Comments
`
`Application Protocols Layer
`
`Protocols specific to applications such as WWW, e-mail, FTP, etc.
`
`Transmission Control Protocol
`Layer
`
`TCP directs packets to a specific application on a computer using a
`port number.
`
`Internet Protocol Layer
`
`IP directs packets to a specific computer using an IP address.
`
`Dropbox Exhibit 1021 - Page 2
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`

`

`Hardware Layer
`
`Converts binary packet data to network signals and back.
`(E.g. ethernet network card, modem for phone lines, etc.)
`
`If we were to follow the path that the message "Hello computer 5.6.7.8!" took from our computer to the
`computer with IP address 5.6.7.8, it would happen something like this:
`
`Diagram 2
`
`1. The message would start at the top of the protocol stack on your computer and work it's way
`downward.
`2. If the message to be sent is long, each stack layer that the message passes through may break the
`message up into smaller chunks of data. This is because data sent over the Internet (and most
`computer networks) are sent in manageable chunks. On the Internet, these chunks of data are
`known as packets.
`3. The packets would go through the Application Layer and continue to the TCP layer. Each packet is
`assigned a port number. Ports will be explained later, but suffice to say that many programs may be
`using the TCP/IP stack and sending messages. We need to know which program on the destination
`computer needs to receive the message because it will be listening on a specific port.
`4. After going through the TCP layer, the packets proceed to the IP layer. This is where each packet
`receives it's destination address, 5.6.7.8.
`5. Now that our message packets have a port number and an IP address, they are ready to be sent
`over the Internet. The hardware layer takes care of turning our packets containing the alphabetic text
`of our message into electronic signals and transmitting them over the phone line.
`6. On the other end of the phone line your ISP has a direct connection to the Internet. The ISPs router
`examines the destination address in each packet and determines where to send it. Often, the
`packet's next stop is another router. More on routers and Internet infrastructure later.
`7. Eventually, the packets reach computer 5.6.7.8. Here, the packets start at the bottom of the
`destination computer's TCP/IP stack and work upwards.
`8. As the packets go upwards through the stack, all routing data that the sending computer's stack
`added (such as IP address and port number) is stripped from the packets.
`9. When the data reaches the top of the stack, the packets have been re-assembled into their original
`form, "Hello computer 5.6.7.8!"
`Networking Infrastructure
`
`So now you know how packets travel from one computer to another over the Internet. But what's in-
`between? What actually makes up the Internet? Let's look at another diagram:
`
`Dropbox Exhibit 1021 - Page 3
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`

`

`Diagram 3
`
`Here we see Diagram 1 redrawn with more detail. The physical connection through the phone network to
`the Internet Service Provider might have been easy to guess, but beyond that might bear some
`explanation.
`
`The ISP maintains a pool of modems for their dial-in customers. This is managed by some form of
`computer (usually a dedicated one) which controls data flow from the modem pool to a backbone or
`dedicated line router. This setup may be refered to as a port server, as it 'serves' access to the network.
`Billing and usage information is usually collected here as well.
`
`After your packets traverse the phone network and your ISP's local equipment, they are routed onto the
`ISP's backbone or a backbone the ISP buys bandwidth from. From here the packets will usually journey
`through several routers and over several backbones, dedicated lines, and other networks until they find
`their destination, the computer with address 5.6.7.8. But wouldn't it would be nice if we knew the exact
`route our packets were taking over the Internet? As it turns out, there is a way...
`
`Check It Out - The Traceroute Program
`
`If you're using Microsoft Windows or a flavor of Unix and have a connection to the Internet, here is
`another handy Internet program. This one is called traceroute and it shows the path your packets are
`taking to a given Internet destination. Like ping, you must use traceroute from a command prompt. In
`Windows, use tracert www.yahoo.com. From a Unix prompt, type traceroute
`www.yahoo.com. Like ping, you may also enter IP addresses instead of domain names. Traceroute
`will print out a list of all the routers, computers, and any other Internet entities that your packets must
`travel through to get to their destination.
`
`If you use traceroute, you'll notice that your packets must travel through many things to get to their
`destination. Most have long names such as sjc2-core1-h2-0-0.atlas.digex.net and fddi0-
`0.br4.SJC.globalcenter.net. These are Internet routers that decide where to send your packets. Several
`routers are shown in Diagram 3, but only a few. Diagram 3 is meant to show a simple network structure.
`The Internet is much more complex.
`Internet Infrastructure
`
`The Internet backbone is made up of many large networks which interconnect with each other. These
`large networks are known as Network Service Providers or NSPs. Some of the large NSPs are UUNet,
`CerfNet, IBM, BBN Planet, SprintNet, PSINet, as well as others. These networks peer with each other to
`exchange packet traffic. Each NSP is required to connect to three Network Access Points or NAPs. At
`the NAPs, packet traffic may jump from one NSP's backbone to another NSP's backbone. NSPs also
`interconnect at Metropolitan Area Exchanges or MAEs. MAEs serve the same purpose as the NAPs but
`
`Dropbox Exhibit 1021 - Page 4
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`

`

`are privately owned. NAPs were the original Internet interconnect points. Both NAPs and MAEs are
`referred to as Internet Exchange Points or IXs. NSPs also sell bandwidth to smaller networks, such as
`ISPs and smaller bandwidth providers. Below is a picture showing this hierarchical infrastructure.
`
`Diagram 4
`
`This is not a true representation of an actual piece of the Internet. Diagram 4 is only meant to demonstrate
`how the NSPs could interconnect with each other and smaller ISPs. None of the physical network
`components are shown in Diagram 4 as they are in Diagram 3. This is because a single NSP's backbone
`infrastructure is a complex drawing by itself. Most NSPs publish maps of their network infrastructure on
`their web sites and can be found easily. To draw an actual map of the Internet would be nearly impossible
`due to it's size, complexity, and ever changing structure.
`The Internet Routing Hierarchy
`
`So how do packets find their way across the Internet? Does every computer connected to the Internet
`know where the other computers are? Do packets simply get 'broadcast' to every computer on the
`Internet? The answer to both the preceeding questions is 'no'. No computer knows where any of the other
`computers are, and packets do not get sent to every computer. The information used to get packets to
`their destinations are contained in routing tables kept by each router connected to the Internet.
`Routers are packet switches. A router is usually connected between networks to route packets between
`them. Each router knows about it's sub-networks and which IP addresses they use. The router usually
`doesn't know what IP addresses are 'above' it. Examine Diagram 5 below. The black boxes connecting the
`backbones are routers. The larger NSP backbones at the top are connected at a NAP. Under them are
`several sub-networks, and under them, more sub-networks. At the bottom are two local area networks with
`computers attached.
`
`Dropbox Exhibit 1021 - Page 5
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`

`

`Diagram 5
`
`When a packet arrives at a router, the router examines the IP address put there by the IP protocol layer on
`the originating computer. The router checks it's routing table. If the network containing the IP address is
`found, the packet is sent to that network. If the network containing the IP address is not found, then the
`router sends the packet on a default route, usually up the backbone hierarchy to the next router. Hopefully
`the next router will know where to send the packet. If it does not, again the packet is routed upwards until
`it reaches a NSP backbone. The routers connected to the NSP backbones hold the largest routing tables
`and here the packet will be routed to the correct backbone, where it will begin its journey 'downward'
`through smaller and smaller networks until it finds it's destination.
`Domain Names and Address Resolution
`
`But what if you don't know the IP address of the computer you want to connect to? What if the you need to
`access a web server referred to as www.anothercomputer.com? How does your web browser know where
`on the Internet this computer lives? The answer to all these questions is the Domain Name Service or
`DNS. The DNS is a distributed database which keeps track of computer's names and their corresponding
`IP addresses on the Internet.
`
`Many computers connected to the Internet host part of the DNS database and the software that allows
`others to access it. These computers are known as DNS servers. No DNS server contains the entire
`database; they only contain a subset of it. If a DNS server does not contain the domain name requested
`by another computer, the DNS server re-directs the requesting computer to another DNS server.
`
`Dropbox Exhibit 1021 - Page 6
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`

`

`Diagram 6
`
`The Domain Name Service is structured as a hierarchy similar to the IP routing hierarchy. The computer
`requesting a name resolution will be re-directed 'up' the hierarchy until a DNS server is found that can
`resolve the domain name in the request. Figure 6 illustrates a portion of the hierarchy. At the top of the tree
`are the domain roots. Some of the older, more common domains are seen near the top. What is not shown
`are the multitude of DNS servers around the world which form the rest of the hierarchy.
`
`When an Internet connection is setup (e.g. for a LAN or Dial-Up Networking in Windows), one primary and
`one or more secondary DNS servers are usually specified as part of the installation. This way, any Internet
`applications that need domain name resolution will be able to function correctly. For example, when you
`enter a web address into your web browser, the browser first connects to your primary DNS server. After
`obtaining the IP address for the domain name you entered, the browser then connects to the target
`computer and requests the web page you wanted.
`
`Check It Out - Disable DNS in Windows
`
`If you're using Windows 95/NT and access the Internet, you may view your DNS server(s) and even
`disable them.
`
`If you use Dial-Up Networking:
`Open your Dial-Up Networking window (which can be found in Windows Explorer under your CD-ROM
`drive and above Network Neighborhood). Right click on your Internet connection and click Properties.
`Near the bottom of the connection properties window press the TCP/IP Settings... button.
`
`If you have a permanent connection to the Internet:
`Right click on Network Neighborhood and click Properties. Click TCP/IP Properties. Select the DNS
`Configuration tab at the top.
`
`You should now be looking at your DNS servers' IP addresses. Here you may disable DNS or set your
`DNS servers to 0.0.0.0. (Write down your DNS servers' IP addresses first. You will probably have to
`restart Windows as well.) Now enter an address into your web browser. The browser won't be able to
`resolve the domain name and you will probably get a nasty dialog box explaining that a DNS server
`couldn't be found. However, if you enter the corresponding IP address instead of the domain name, the
`browser will be able to retrieve the desired web page. (Use ping to get the IP address prior to disabling
`DNS.) Other Microsoft operating systems are similar.
`
`Dropbox Exhibit 1021 - Page 7
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`

`

`Internet Protocols Revisited
`
`As hinted to earlier in the section about protocol stacks, one may surmise that there are many protocols
`that are used on the Internet. This is true; there are many communication protocols required for the
`Internet to function. These include the TCP and IP protocols, routing protocols, medium access control
`protocols, application level protocols, etc. The following sections describe some of the more important and
`commonly used protocols on the Internet. Higher level protocols are discussed first, followed by lower
`level protocols.
`Application Protocols: HTTP and the World Wide Web
`
`One of the most commonly used services on the Internet is the World Wide Web (WWW). The application
`protocol that makes the web work is Hypertext Transfer Protocol or HTTP. Do not confuse this with the
`Hypertext Markup Language (HTML). HTML is the language used to write web pages. HTTP is the
`protocol that web browsers and web servers use to communicate with each other over the Internet. It is an
`application level protocol because it sits on top of the TCP layer in the protocol stack and is used by
`specific applications to talk to one another. In this case the applications are web browsers and web
`servers.
`
`HTTP is a connectionless text based protocol. Clients (web browsers) send requests to web servers for
`web elements such as web pages and images. After the request is serviced by a server, the connection
`between client and server across the Internet is disconnected. A new connection must be made for each
`request. Most protocols are connection oriented. This means that the two computers communicating with
`each other keep the connection open over the Internet. HTTP does not however. Before an HTTP request
`can be made by a client, a new connection must be made to the server.
`
`When you type a URL into a web browser, this is what happens:
`
`1. If the URL contains a domain name, the browser first connects to a domain name server and
`retrieves the corresponding IP address for the web server.
`2. The web browser connects to the web server and sends an HTTP request (via the protocol stack) for
`the desired web page.
`3. The web server receives the request and checks for the desired page. If the page exists, the web
`server sends it. If the server cannot find the requested page, it will send an HTTP 404 error
`message. (404 means 'Page Not Found' as anyone who has surfed the web probably knows.)
`4. The web browser receives the page back and the connection is closed.
`5. The browser then parses through the page and looks for other page elements it needs to complete
`the web page. These usually include images, applets, etc.
`6. For each element needed, the browser makes additional connections and HTTP requests to the
`server for each element.
`7. When the browser has finished loading all images, applets, etc. the page will be completely loaded in
`the browser window.
`
`Check It Out - Use Your Telnet Client to Retrieve a Web Page Using HTTP
`
`Telnet is a remote terminal service used on the Internet. It's use has declined lately, but it is a very
`useful tool to study the Internet. In Windows find the default telnet program. It may be located in the
`Windows directory named telnet.exe. When opened, pull down the Terminal menu and select
`Preferences. In the preferences window, check Local Echo. (This is so you can see your HTTP request
`when you type it.) Now pull down the Connection menu and select Remote System. Enter
`www.google.com for the Host Name and 80 for the Port. (Web servers usually listen on port 80 by
`default.) Press Connect. Now type
`GET / HTTP/1.0
`
`Dropbox Exhibit 1021 - Page 8
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
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`

`

`and press Enter twice. This is a simple HTTP request to a web server for it's root page. You should see
`a web page flash by and then a dialog box should pop up to tell you the connection was lost. If you'd
`like to save the retrieved page, turn on logging in the Telnet program. You may then browse through the
`web page and see the HTML that was used to write it.
`
`Most Internet protocols are specified by Internet documents known as a Request For Comments or
`RFCs. RFCs may be found at several locations on the Internet. See the Resources section below for
`appropriate URL's. HTTP version 1.0 is specified by RFC 1945.
`Application Protocols: SMTP and Electronic Mail
`
`Another commonly used Internet service is electronic mail. E-mail uses an application level protocol called
`Simple Mail Transfer Protocol or SMTP. SMTP is also a text based protocol, but unlike HTTP, SMTP is
`connection oriented. SMTP is also more complicated than HTTP. There are many more commands and
`considerations in SMTP than there are in HTTP.
`
`When you open your mail client to read your e-mail, this is what typically happens:
`
`1. The mail client (Netscape Mail, Lotus Notes, Microsoft Outlook, etc.) opens a connection to it's
`default mail server. The mail server's IP address or domain name is typically setup when the mail
`client is installed.
`2. The mail server will always transmit the first message to identify itself.
`3. The client will send an SMTP HELO command to which the server will respond with a 250 OK
`message.
`4. Depending on whether the client is checking mail, sending mail, etc. the appropriate SMTP
`commands will be sent to the server, which will respond accordingly.
`5. This request/response transaction will continue until the client sends an SMTP QUIT command. The
`server will then say goodbye and the connection will be closed.
`A simple 'conversation' between an SMTP client and SMTP server is shown below. R: denotes messages
`sent by the server (receiver) and S: denotes messages sent by the client (sender).
`
` This SMTP example shows mail sent by Smith at host USC-ISIF, to
` Jones, Green, and Brown at host BBN-UNIX. Here we assume that
` host USC-ISIF contacts host BBN-UNIX directly. The mail is
` accepted for Jones and Brown. Green does not have a mailbox at
` host BBN-UNIX.
`
` -------------------------------------------------------------
`
` R: 220 BBN-UNIX.ARPA Simple Mail Transfer Service Ready
` S: HELO USC-ISIF.ARPA
` R: 250 BBN-UNIX.ARPA
`
` S: MAIL FROM:<Smith@USC-ISIF.ARPA>
` R: 250 OK
`
` S: RCPT TO:<Jones@BBN-UNIX.ARPA>
` R: 250 OK
`
` S: RCPT TO:<Green@BBN-UNIX.ARPA>
` R: 550 No such user here
`
` S: RCPT TO:<Brown@BBN-UNIX.ARPA>
` R: 250 OK
`
` S: DATA
` R: 354 Start mail input; end with <CRLF>.<CRLF>
` S: Blah blah blah...
` S: ...etc. etc. etc.
`
`Dropbox Exhibit 1021 - Page 9
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`

`

` S: .
` R: 250 OK
`
` S: QUIT
` R: 221 BBN-UNIX.ARPA Service closing transmission channel
`This SMTP transaction is taken from RFC 821, which specifies SMTP.
`Transmission Control Protocol
`
`Under the application layer in the protocol stack is the TCP layer. When applications open a connection to
`another computer on the Internet, the messages they send (using a specific application layer protocol) get
`passed down the stack to the TCP layer. TCP is responsible for routing application protocols to the
`correct application on the destination computer. To accomplish this, port numbers are used. Ports can
`be thought of as seperate channels on each computer. For example, you can surf the web while reading e-
`mail. This is because these two applications (the web browser and the mail client) used different port
`numbers. When a packet arrives at a computer and makes its way up the protocol stack, the TCP layer
`decides which application receives the packet based on a port number.
`
`TCP works like this:
`
`When the TCP layer receives the application layer protocol data from above, it segments it into
`manageable 'chunks' and then adds a TCP header with specific TCP information to each 'chunk'.
`The information contained in the TCP header includes the port number of the application the data
`needs to be sent to.
`When the TCP layer receives a packet from the IP layer below it, the TCP layer strips the TCP
`header data from the packet, does some data reconstruction if necessary, and then sends the data
`to the correct application using the port number taken from the TCP header.
`
`This is how TCP routes the data moving through the protocol stack to the correct application.
`TCP is not a textual protocol. TCP is a connection-oriented, reliable, byte stream service. Connection-
`oriented means that two applications using TCP must first establish a connection before exchanging data.
`TCP is reliable because for each packet received, an acknowledgement is sent to the sender to confirm
`the delivery. TCP also includes a checksum in it's header for error-checking the received data. The TCP
`header looks like this:
`
`Diagram 7
`
`Notice that there is no place for an IP address in the TCP header. This is because TCP doesn't know
`anything about IP addresses. TCP's job is to get application level data from application to application
`reliably. The task of getting data from computer to computer is the job of IP.
`
`Dropbox Exhibit 1021 - Page 10
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`

`

`Check It Out - Well Known Internet Port Numbers
`
`Listed below are the port numbers for some of the more commonly used Internet services.
`
`FTP
`Telnet
`SMTP
`HTTP
`Quake III
`Arena
`
`20/21
`23
`25
`80
`27960
`
`Internet Protocol
`
`Unlike TCP, IP is an unreliable, connectionless protocol. IP doesn't care whether a packet gets to it's
`destination or not. Nor does IP know about connections and port numbers. IP's job is too send and route
`packets to other computers. IP packets are independent entities and may arrive out of order or not at all.
`It is TCP's job to make sure packets arrive and are in the correct order. About the only thing IP has in
`common with TCP is the way it receives data and adds it's own IP header information to the TCP data.
`The IP header looks like this:
`
`Diagram 8
`
`Above we see the IP addresses of the sending and receiving computers in the IP header. Below is what a
`packet looks like after passing through the application layer, TCP layer, and IP layer. The application layer
`data is segmented in the TCP layer, the TCP header is added, the packet continues to the IP layer, the IP
`header is added, and then the packet is transmitted across the Internet.
`
`Diagram 9
`
`Dropbox Exhibit 1021 - Page 11
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`

`

`Wrap Up
`
`Now you know how the Internet works. But how long will it stay this way? The version of IP currently used
`on the Internet (version 4) only allows 232 addresses. Eventually there won't be any free IP addresses left.
`Surprised? Don't worry. IP version 6 is being tested right now on a research backbone by a consortium of
`research institutions and corporations. And after that? Who knows. The Internet has come a long way
`since it's inception as a Defense Department research project. No one really knows what the Internet will
`become. One thing is sure, however. The Internet will unite the world like no other mechanism ever has.
`The Information Age is in full stride and I am glad to be a part of it.
`
`Rus Shuler, 1998
`Updates made 2002
`Resources
`
`Below are some interesting links associated with some of the topics discussed. (I hope they all still work.
`All open in new window.)
`
`http://www.ietf.org/ is the home page of the Internet Engineering Task Force. This body is greatly
`responsible for the development of Internet protocols and the like.
`
`http://www.internic.org/ is the organization responsible for administering domain names.
`
`http://www.nexor.com/public/rfc/index/rfc.html is an excellent RFC search engine useful for finding any
`RFC.
`
`http://www.internetweather.com/ shows animated maps of Internet latency.
`
`http://routes.clubnet.net/iw/ is Internet Weather from ClubNET. This page shows packet loss for various
`carriers.
`
`http://navigators.com/isp.html is Russ Haynal's ISP Page. This is a great site with links to most NSPs and
`their backbone infrastructure maps.
`Bibliography
`
`The following books are excellent resources and helped greatly in the writing of this paper. I believe
`Stevens' book is the best TCP/IP reference ever and can be considered the bible of the Internet. Sheldon's
`book covers a much wider scope and contains a vast amount of networking information.
`
`TCP/IP Illustrated, Volume 1, The Protocols.
`W. Richard Stevens.
`Addison-Wesley, Reading, Massachusetts. 1994.
`Encyclopedia of Networking.
`Tom Sheldon.
`Osbourne McGraw-Hill, New York. 1998.
`
`Although not used for writing this paper, here are some other good books on the topics of the Internet and
`networking:
`
`Firewalls and Internet Security; Repelling the Wiley Hacker.
`William R. Cheswick, Steven M. Bellovin.
`Addison-Wesley, Reading, Massachusetts. 1994.
`Data Communications, Computer Networks and Open Systems. Fourth Edition.
`Fred Halsall.
`
`Dropbox Exhibit 1021 - Page 12
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`

`

`Addison-Wesley, Harlow, England. 1996.
`Telecommunications: Protocols and Design.
`John D. Spragins with Joseph L. Hammond and Krzysztof Pawlikowski.
`Addison-Wesley, Reading, Massachusetts. 1992.
`
`Dropbox Exhibit 1021 - Page 13
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`