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Networking 1 A crash course in networking (Because Networking 101 requires more time) Networking 1 Tutorial_2006.ppt Page 1 Network Design Triangle Maturity Policy $$$ Cost $$$ Protocols Architecture Scalability Mobility Security QoS Bandwidth Networking 1 Tutorial_2006.ppt © 2004 Syzygy Engineering – Will Ivancic Page 2 Protocol Stack OSI Model TCP/IP Model Application Application E-Mail, FTP, Web Browsing, etc… Transport Transport TCP, UDP, SCTP, etc… Network Network Data Link Data Link Physical Physical Presentation Session Networking 1 Tutorial_2006.ppt IPv4, IPv6 IEEE 802, SONET Frame Relay (HDLC), etc… Wire, Fiber, RF, etc… Page 3 CCSDS relationship with the OSI Layers Networking 1 Tutorial_2006.ppt Page 4 Network Layers • Why Layering? – Flexibility – Extensibility – Divide and conquer • Transport Layer – Protocols to move data between end systems • Network Layer – End-to-End addressing – Routing and Forwarding • Data Link Layer – Point-to-Point addressing – Maps Network to physical layers – Provides media access (CDMA, TDMA, FDMA, Collision Sense Multiple Access, Aloha) Networking 1 Tutorial_2006.ppt Page 6 Why all the confusion with TCP? • TCP/IP (Transmission Control Protocol/Internet Protocol Suite) – A suite of protocols – Over 4000 Request for Comments (RFCs) – NOTE! Often times the term TCP is used as short hand for the TCP/IP protocol Suite. Lately, an attempt has been made to use IP for identify the TCP/IP protocols suite to alleviate the confusion between the TCP/IP suite and TCP the transport protocol. • TCP (Transmission Control Protocol) – A Reliable Transport Protocol – Designed for fairness • Optimized for shared links • Congestion Control (Multiplicative Decrease / Additive Increase) • Self-Probing to discover link capacity – Delay and bandwidth sensitive (bandwidth/delay product) • UDP (User Datagram Protocol) – An Unreliable Transport Protocol – No Congestion Control – Insensitive to delay • IPv4 and IPv6 (Internet Protocol version 4 and Internet Protocol version 6) – Internet Protocols used to identify and route packets – Source and Destination Addresses – Quality of Service Bits – Hop Count (Used to keep packets from propagating continuously – IP is insensitive to delay Networking 1 Tutorial_2006.ppt Page 7 Routing • Dynamic Routing is a service (application) • Types/Terms – Default (Route of last resort) – Static (Predetermined) – Dynamic • Interior Gateway Protocols – RIP (Routing Information Protocol) » Small Networks – Open Shortest Path First (OSPF) » Many additional metrics available » Widely used in large networks (e.g. DoD, Businesses, Universities) • Exterior Gateway Protocols – BGP (Boarder Gateway Protocol) » Used in the Big Internet such as between ISPs (Internet Service Providers) – MANETs (Mobile Ad hoc NETworks) • Self-configuring and self-organizing network of mobile nodes usually connected via wireless links • Proactive routing protocols Optimized Link State Routing (OLSR), Open Shortest Path First (OSPF) extension – Applicable for relatively stable networks – Suitable for large and dense networks • Reactive routing protocol Ad Hoc On-Demand Distance Vector (AODV), Dynamic Source Routing protocol (DSR), Dynamic MANET On-demand (DYMO) Networking 1 Tutorial_2006.ppt – Applicable to highly dynamic networks Page 8 Delay/Disruption Tolerant Networking (DTN) Store Forward DTN • Long delays • Need to schedule assets DTN • Opportunistic • Low delay • Possibly no need to schedule assets DTN is really an application overlay that has aspects of scheduling, data transport and routing. Networking 1 Tutorial_2006.ppt Page 9 Network Security • Where – Data/Application • End-to-End – Transport • Transport Layer Security (TLS) • End-to-End – Network • IPsec (IP Security) • End-to-End – Data-Link Layer (Bulk Encryption) • Key Types – Symmetric • Pre-placed Keys • Insensitive to delay – Asymmetric • Public Key Infrastructure (PKI) • Generally sensitive to delay • Issues – Key Management – Policy Management – ITAR • Point-to-Point Networking 1 Tutorial_2006.ppt Page 10 Network – Rules of Thumb • Metcalfe's law: The value of a telecommunications network is proportional to the square of the number of users of the system (N2). Actually N(N-1)/2 – Internet,World Wide Web Operating systems, Applications, Social networking • Andrew Odlyzko’s and Benjamin Tilly’s law: The value of a network with N members is not n squared, but rather N x log(N) – Reason: Not all potential connections in a network are equally valuable. • Reed's law: the utility of large networks, particularly social networks, can scale exponentially with the size of the network. – The number of possible sub-groups of network participants is 2N-N-1 , where N is the number of participants. This grows much more rapidly than either • the number of participants, N, • or the number of possible pair connections, N(N-1)/2 – Even if the utility of groups available to be joined is very small on a pergroup basis, eventually the network effect of potential group membership can dominate the overall economics of the system Networking 1 Tutorial_2006.ppt Page 11 Summary and Important Information • Network design entails Policy, Protocols and Architecture • Protocols are tools – Be sure to apply the proper tool relative to the environment being used. • TCP/IP is a suite of international commercial-off-the-shelf protocols – Protocols that require handshaking or a response/replay do not work over long delays and intermittently connected networks – Protocols that require infrastructure may not necessarily be applicable to space unless caching of information is used. – Many TCP/IP protocols are delay insensitive and can be utilized in a variety of environments. • Default routes and Static routes can get one in trouble – be careful • One of the great powers of COTS products is the debugging tools • There was an excellent tutorial on the distinctions between routing, switching, and bridging at the following URL: – http://www3.ietf.org/proceedings/06mar/slides/rbst-0.pdf Networking 1 Tutorial_2006.ppt Page 12