Link technologies Reaching the Network of networks Alberto Escudero-Pascual firstname.lastname@example.org@it.kth.se http://www.it.kth.se/~aep Royal Institute of Technology Sweden 1st International Workshop on Open Access 4-7 June 2003, Stockholm, Sweden
Link level technologies… or how to get connected to the Internet Goal: Brief technical overview of some of the most common technologies to connect to Internet in developing countries… How: What is the Internet? What is to be connected? Review five (radio) link level technologies.
What is the Internet? Federal Networking Council (DoD, NASA et al), Internet Monthly Reports, October 1995 agrees that the following language reflects our definition of the term "Internet". "Internet" refers to the global information system that: is logically linked together by a globally unique address space based on the Internet Protocol (IP) or its subsequent extensions/follow-ons; is able to support communications using the Transmission Control Protocol/Internet Protocol (TCP/IP) suite or its subsequent extensions/follow-ons, and/or other IP-compatible protocols; and provides, uses or makes accessible, either publicly or privately, high level services layered on the communications and related infrastructure described herein.
What is the Internet? The Internet is a group of interconnected networks which has evolved more-or-less independently of any social, political, or governmental control. The Internet is a network of networks - billions of computers, all connected together. The Internet is the internet of networks
What is the Internet? Humanities and Arts: Sharing Center Stage on the Internet, IETF RFC2150, 1997 People, computers and information electronically linked around the world by a common Protocol for communicating with each other.
Connected to the Internet? Reach a computer that can exchange IP packets with other computers around the world at anytime. Reach the linked, reach those connected. or reach a concrete service gateway. Connect to the Internet is to make sure that the information that we send (receive) can reach a place where can be routed (forwarded) inside of IP packet to others. Connect to the Internet is being able to reach a IP-based Post office
Reaching the linked world… VSAT DVB (MPE) Wi-Fi (IEEE 802.11) Packet Radio (AX.25) HF-Mail
DVB (Digital Video Broadcast) Users access Web sites through their low-speed Internet connection Receive multimegabit data streams back through a TV dish antenna on the roof. The DVB cards convert incoming RF satellite signals and place them back in the TCP/IP stack. DVB uses IP encapsulation technology to make Internet traffic look like MPEG-2 data. Cheap receivers (200 USD)
AX.25 is considered the defacto standard protocol for amateur radio since early 70s 3-30 Mhz (HF), 140 Mhz (VHF) and 435 Mhz (UHF) Connected & connectionless modes of operation, and is used either by itself for point-point links, or to carry other protocols such as TCP/IP and NetRom. For HF packet, 300 BPS data is used over single side band (SSB) modulation. For 1200/2400 bps UHF/VHF packet, commonly available narrow band FM voice radios are used. For high speed packet (starting at 9600 bps), special radios or modified FM radios must be used.