Flyover: Network Architectures Basics

        Media
        Protocols
        Connectors
        Network software
        Network OS
        Upper layer

Media - LAN

        twisted pair  - cat 3 and cat 5
        coax - thick wire and thin wire
        spread spectrum  - grouper
        other wireless
        fiber

Media and packaging for WANs

        fiber
        sonet (ppp)
        satellite
                GEOS and LEOS
        the T series
        frame relay
        xDSL
        isdn
        cable modems
        atm

Rules of thumb

        speed of light in fiber =2/3c
        RTT of a lan = 1 ms
        x-country latency = 24 ms
        x-country RTT of a bit = 100 ms
        one-way end-end delay of a satellite = 500 ms

Criteria for evaluating media

        driving distance - mbaudfeet
        characteristics of errors-
                why, burstiness, consequence
        characteristics of failure
                when, where, mtbf, mttr, graceful and graceless
        conservation of technologies and training
        cards
        technological gradients

Key concepts

        length of a bit (speed of signal and prop delay of media)
        latency and bandwidth
        RTT
        delayxbandwidth product and frames in flight
        length of media in frames
        scalability
        orders of magnitude
        economics of speed
        multiplexing - costs and benefits

MAC Protocols

        fddi
        ether -switched, fast, shared, gigabit
        hdlc

Network Protocols

        SNA, Decnet, Appletalk
        IP, IPX
        TCP

Connectors

        Repeaters, Bridges,  Hubs
                level of connectivity
                management issues
                price-performance
        Switches
                types
                management issues
        Routers and hybrids
                cards and backplanes
                cpu
        Gateways
                protocol level
                application level
                political level
        Terminal Servers and Modems -
                types of connectivity
                SLIP and PPP
                stats, callbacks, detail recording
                rack >> standalone

Communications Software

        Network Layer
        Name Service, Routing, Monitoring,
        Routing Issues
                protocols
                        internal vs external  - goals/approaches.
                congestion control
                autonomous systems and routing
                class, classless, ALE and addressing and IP v6
        Multicast

Endpoints and hosts

        Desktops
                middleware
                versions and configurations
                security
        Servers
                data servers
                computation servers
                application servers
                advertising
                performance
        Mainframes
                channels and storage

Network Operating System Software

        Goals - Printing, Shared Files, LAN apps
        Novell, NFS, DCE, NT 5.0
        Sharing applications and data

Upper layer Software

        Session Layer
        Presentation Layer
        Application Layer
        certs and tickets and cookies

User Layer

        Telnet, Ftp, email, Browsers
        Browser wars
        Clients (fat and thin)
        Networked computers

User Support Layer

        Support and training
        Remote access (local and mobile)
        Glue (ids, security, interoperability)