Large-scale (Campus) Lan design (Part I)

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Large-scale (Campus) Lan design (Part I)

• Introduce campus LANs
• Review basic LAN topologies
• LAN Switching evolution from shared LANs
• LAN Switching vs Routing

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Large-scale (Campus) LAN

• Local area
• constrained to a fixed geographical area

• Uses LAN technologies Ethernet/Fast/Gigabit,
  Token Ring, FDDI, ATM
• Switching and routing technologies

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Example of a campus network
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Basic LAN topologies
                         

• Bus
• RingFDDI
• Star
• All are prone to scalability problems

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Evolution from shared to switched networks

• Factors stressing capabilities of traditional
  (shared) LANS
• Faster CPUs
• Faster Operating Systems
• Network-intensive applications

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Simple LAN switch
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Benefits of switching

• Bandwidth (not shared)
• VLANs
• Security

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Routers

• Routers use Layer 3 information to make routing
  decisions (routing tables) and choose the
  optimal path
• Routers use routing protocols (e.g. OSPF, BGP) to
  exchange updates/routing info
• Routers filter broadcasts and multicasts,
  switches dont can create broadcast storm
• Routers create separate broadcast domains
• Switches dont have network (host) addresses,
  routers do.
• Routers modify destinations physical (not
  network) address

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Switching vs Routing
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Reliability (Fault-Tolerance) Mechanisms

• Layer 2 - STP (Spanning Tree Protocol IEEE 802.1D
  (newer protocols include RSTP and MSTP)

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Spanning Tree Port States
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Reliability (Fault-Tolerance) Mechanisms

• Layer 3 VRRP and HSRP

A typical LAN
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Reliability (Fault-Tolerance) Mechanisms

• Layer 3 VRRP and HSRP

HSRP addressing