chapter 19 -- networking technologies past and present

(rev. March 29, 2015)

Notes On Chapter Nineteen -- Networking Technologies Past and Present

19.0 Study Guide
- Be able to discuss these technologies (much of this is review from previous chapters)
  - T-series circuits
  - OC circuits
  - DSL & cable modems
  - WiFi and WiMax
  - ARPA net
  - X.25
  - ATM
  - MPLS
  - VoIP
19.1 Introduction
- Quick summary of technologies that have had a lasting impact
  - because the technology is still being used, or
  - because they contributed ideas that are still important.
19.2 Connection and Access Technologies
- 19.2.1 Synchronous Optical Networks or Digital Hierarchy (SONET/SDH)
  - "permits a physical ring to be constructed with the purpose of providing redundancy"
- 19.2.2 Optical Carrier (OC)
  - Signaling used on optical fiber
- 19.2.3 Digital Subscriber Line (DSL and Cable Modems
  - Principle current technology for broadband to homes and small businesses.
  - DSL offers 1 to 6 Mbps
  - Cable modem offers up to 53 Mbps to be shared by a group
  - Fiber to the curb or home is expected to eventually replace DSL and cable modem.
- 19.2.4 WiMAX and WiFi
  - Wi-Fi is a set of LAN technologies widely adapted to implement small inexpensive LANs. Data rates have increased impressively over a relatively short period of development.
  - WiMAX is a wireless broadband technology that can provide the infrastructure for a MAN.
  - WiMAX is in use providing access to subscribers, and also in backhaul applications, e.g. between cell towers and a service providers central network facility.
  - There are two versions of WiMAX - one for fixed stations and one for 'mobile endpoints'.
- 19.2.5 Very Small Aperture Satellite
  - Provides Internet service to homes and small businesses.
  - High data rates
  - Long Delays
- 19.2.6 Power Line Communications (PLC)
  - Uses high frequency to send data through power lines.
  - Much research has been done, but not much deployment.
19.3 LAN Technologies
- 19.3.1 IBM Token Rings
  - IBM created this token-passing ring LAN technology.
  - Originally 4 Mbps and later 16 Mbps
  - Widely accepted in the corporate sector for many years
- 19.3.2 Fiber and Copper Distributed Data Interconnect (FDDI and CDDI)
  - In the late 1980's and early 90's, this was the answer to slow 10 Mbps Ethernets and 16 Mbps IBM Token Rings.
  - FDDI offered 100 Mbps data rates and a redundant counter-rotating ring technology
  - There was some reluctance to adopt it because of the expense and expertise required to deal with fiber.
  - CDDI (copper implementation) was introduced to help lower cost and complexity.
  - FDDI and CDDI eventually became obsolete because customers preferred Ethernet.
- 19.3.3 Ethernet
  - Ethernet is now extremely dominant as a network technology.
  - However Ethernet evolved and changed drastically compared to its original form.
19.4 WAN Technologies
- 19.4.1 ARPANET
  - A project of the US Defense Department Advanced Research Projects Agency (DARPA).
  - One of the first packet-switched WANs
  - Originally connected researchers in academia and the military
  - Precursor to the Internet
  - Provided the first Internet backbone
- 19.4.2 X.25
  - Early standard for WAN technology developed by what is now the International Telecommunications Union (ITU).
  - Popular with public carriers in its time
  - Was more popular in Europe than the US
  - Had a traditional WAN design: leased lines connected by packet switches having directly-connected computers.
  - Connection oriented
  - Invented before the era of PC's.
  - Often used to connect remote terminals
  - CSU Stanislaus' first connection to the Internet was over an X.25 link that provided a path to the Chancellor's Office.
- 19.4.3 Frame Relay
  - Invented by long-distance voice carriers
  - Inventors envisioned it to bridge LAN segments at LAN data rates of 4-100 Mbps.
  - Connection oriented
  - Expensive
  - Lower-bandwidth versions (56Kbps - 1.5 Mbps) were somewhat cheaper.
  - Popular until lower cost alternatives came along
- 19.4.4 Switched Multi-megabit Data Service (SMDS)
  - Invented by long-distance voice carriers
  - Based on an IEEE standard
  - High Speed
  - Small packet headers
  - Connectionless
  - Didn't catch on - partly because telephone companies were more comfortable with connection-oriented technologies.
- 19.4.5 Asynchronous Transfer Mode (ATM)
  - Designed to "do it all" - WAN, LAN, voice, video, data
  - Promised superior scalability, partly through the use of "label switching" technology that would get packets through switches faster than conventional forwarding methods.
  - Features included quality of service guarantees (e.g. bandwidth minimums and delay maximums)
  - It enjoyed limited success for quite a few years
  - It was pretty much gone by 2015.
- 19.4.6 MultiProtocol Label Switching (MPLS)
  - A follow-on from ATM technology
  - Label switching used at the center of the Internet
  - Provides a way to allow packets to follow a specific path (a service for which some users will pay extra).
- 19.4.7 Integrated Services Digital Network (ISDN)
  - An early service created by phone companies to perform better than dial-up modem service.
  - Now mostly supplanted by DSL, cable modem and 3G cellular services.
- 19.4.8 Voice and Video over IP (VoIP): SIP and H.323
  - Popular technologies - one can purchase routers that give priority to VoIP traffic.
  - The IETF Session Initiation Protocol (SIP) and ITU H.323 are two standards for implementing VoIP and integrating it with telephone company networks.
- 19.4.9 Software Defined Networking (SDN) and OpenFlow
  - The idea: separate network management software from the networking devices being managed
  - For example OpenFlow software on a PC running Linux managing the forwarding configuration on an Ethernet switch.
  - Provides owners with network management software that works with arbitrary vendor's equipment