What is the Internet?

It’s My Internet and I want it Now!

Enjoying myself in front of a Internet Service Provider

Internet: A network of connections

What is the Internet Used For?

1. Email
2. WWW (webpages)
3. Voice Over IP (VoIP)

How the Internet is Organized.

1. Intranet: A network used internally by an enterprise. Virtual Private Networks (VPN): Allows workers to connect to a company’s Intranet from away.
2. Extranet: A network used by an enterprise to connect with customers and suppliers.

History: The POTS network supported only voice and fax, but the internet supports that and data applications such as the World Wide Web and email.

Classified by size:

1. Wide Area Network (WAN): Owned by large Internet Service Providers (ISPs) and cover continents.
2. Metropolitan Area Network (MAN): Owned by ISPs and cover metropolitan areas.
3. Local Area Network (LAN): Network within small area such as a residence, school, laboratory, university campus, or office building.

Networks are connected by routers.

1. Edge routers: connect two networks. Use Authentication, Bandwidth Management, and Quality of Service (QoS).
2. Core routers: Within IP networks. Use high speed packet forwarding and QoS.

LAN technologies:

1. Firewall: Contains rules to prevent user access to unsecured applications and unauthorized access to the network (LAN).
2. Router: Forwards IP packets within the network and connects the LAN to other LANs.
3. Hub: Receives IP packets and broadcasts the packet to all other ports. Ports are destinations.
4. Switch: Sends IP packet to only one port.
5. Access Point: Base station for wireless LAN that connects wireless to wired.
6. Domain Name System (DNS): Server that translates domain names to an IP address.
7. Host: Any computer that connects to the LAN.
8. DHCP Server: Assigns IP addresses to hosts.
9. E-mail Server: Sends and receives emails.
10. Proxy Server: Controls application traffic. Caches content to speed up transfers.
11. Virtual LANs (VLANs): Allow users not to be close to the LAN. Allows greater network management. Allow for mobile backhauls which help control network traffic.

What is IP Protocol?

How data is handled in the internet.

Here is the stack of how data is handled.

1. Application Layer: Specific to the host’s use for the internet. Example is Simple Mail Transfer Protocol for email. There is also HTTP, FTP, and VolIP.
2. Transport Layer: Uses Transmission Control Protocol (TCP) to break down the email data into multiple segments/packets, each has its own header. Alternate to TCP is UDP.
3. Network Layer: IP adds a header (source and destination) and the data is now known as a IP packer/IP datagram.
4. Data Link Layer: Ethernet adds its own header for information about transferring packets on the LAN. Alternate to Ethernet is ATM, Frame Relay, and Wireless. IP is great because it can work with all kinds of Data Link Layers.
5. Physical Layer: Uses wires or wireless to transfer the data.

Information is then sent through the stack in reverse to get to the host/client.

What is needed for IP to work?

1. Large Address Space: With a large number of devices, a large number of IP addresses are needed.
2. Host Configuration: A way to manage the growth of IP networks. Uses Dynamic Host Configuration Protocol (DHCP) and Point-to-Point Protocol (PPP) to automatically configure network parameters.
3. Security: Large amount of government and enterprise use that needs to be protected. Protocols used such as IPSec, Secure Socket Layer (SSL) and Remote Dial Up Access User Services (RADIUS). Firewall and application proxy are used as well.
4. Guaranteed QoS: Commercial applications like voice calls need low delay and high reliability. Tools that can be used are DiffServ and IntServ (RSVP) protocols.
5. Large Packet Size: To support data intensive applications like move downloads.
6. Mobility: Mobile IP protocol or General Packet Radio Service (GPRS) are used to provide mobility for wireless IP devices.
7. Doesn’t allow broadcast addresses for improved bandwidth efficiency and security.
8. Anycast is introduced to allow applications to discuver services they might need without network knowledge.
9. Address Resolution Protocol (ARP): Matches physical or layer 2 addresses with network or IP addresses. This speeds up getting attached to a new network as mobile users roam.

What is Next for IP? IPv6 (version 6)

1. Large number of IP addresses: Supports 128 bits long IP addresses. These are assigned automatically.
2. QoS: Flow labels are introduced to improve QoS.
3. Security: IPSec are built into IPv6.
4. Mobility: 3GPP is standard.
5. Packet Size: Packet sizes up to 4 GB are supported.
6. IPv6 is not backwards compatible with IPv4.

Moving from IPv4 to IPv6

Option 1: Require routers and hosts to support both.

Option 2: Tunneling: Enables interconnection of IP clouds.

Option 3: Translation: Used when an IPv6 only host has to communicate with an IPv4 host. Uses Application-Level Gateways (ALGs) for conversion from IPv4 to IPv6.