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Campus Networks, Various Topics Eric Brown, Network Architect, VT Agenda • • • • • • • • • • • Network Cardinality Switching versus Routing Network Topology Wireless Coverage, Use, Engineering Internet Connectivity Electronic Message Boards Copyright Complaints Network Security Network Documentation TCP Future Network Cardinality • • • • • • • • • • • • 35,000 users 6 primary switching centers 120 buildings 415 equipment rooms 100,000 horizontal links 27,000 active wired Ethernet connections 1500 access switches 450 distribution switches 50 routers (core, IPv6, data-center, WAN, border) 13,000 phones (5000 that never get used) 5000 cable television connections 200 modem pool connections Switching versus Routing • How has routing/switching tradeoff changed over time • One large bridged LAN (c. 1985) • Routed IP + Appletalk + IPX, FDDI ring core, Other protocols bridged (c. 1992) • ATM + Emulated LAN: Ouch! (c. 1995) • Gigabit Ethernet core, Ethernet to Ethernet routing (c. 1999) • Increasing reach of routing: to some buildings (c. 2006) Switching versus Routing • Liabilities of switching: • Generally no visibility into switched network unless you are on it • No support for multiple valid paths, • ARP is hearsay and potentially dangerous • Both IP and Ethernet have a notion of mutlicast • Implementing multicast requires some mapping between layers • High risk of soft failures (a misplaced root in a large network can lead to very inefficient operation) • No real support for default gateway redundancy, we have to fake it through VRRP or HSRP • No TTL, i.e. no stop gap way to remove old frames from the network Switching versus Routing • Benefits of switching • Network Address use efficiency, too small of subnets leads to inefficient use of IP addresses • Address portability • Simple network configuration • Subnets create convenient boundary for implementing policy “Soft Failure” in the LAN Primary Backup ROOT “Soft Failure” in the LAN Primary ROOT ?! Backup SPANNING KUDZU! Diameter = 8?! Core Topology BUR Core Switch/Router Remote Access ISB Data Center SHA Core Switch/Router ISB Core Switch/Router OWE Core Switch/Router HIL Core Switch/Router ISB Border Switch/Router MSAP ISB Border Router ISB Border Router Internet Internet2 McLean NLR Ashurn CAS Core Switch/Router Remote offices DSL/T-1 Wireless Coverage Wireless Utilization Current Wireless Deployment • • • • • Over 20,000 Registered Users Over 6,000 Simultaneous Users, Daily 1,726 Light-weight Wireless Access Points 24 Cisco wireless controllers 2 Stand-alone Application Services Appliances providing NAT • 6 RADIUS Servers • 1 Very Tired Spectrum Analyzer Wireless RF planning Equinix MBC 10GE Cassell National Lambda Rail MAX / Internet2 Level3 Cogent Equinix Exchange Hurricane Electric Cogent TransitRail Future Internet Connectivity MBC 10GE McLean Verizon 10 GE ISB Network Metrics Internet – 10G Ethernet – Daily Internet – 10G Ethernet – Monthly Classroom Emergency Notification Openfire INS Alert Agent Jabber/XMPP OAMP Sign Controller Diagnostic Agent Sign Controller SSH sign sign sign Sign Agents and Adapters Sign Controller