1. Large-scale (Campus) Lan design (Part I)
Introduce campus LANs
Review basic LAN topologies
LAN Switching: evolution from shared LANs
LAN Switching vs Routing

2. 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

3. Example of a campus network

4. Basic LAN topologies Bus Ring FDDI Star
                         
Basic LAN topologies
Bus
Ring FDDI
Star
All are prone to scalability problems

5. Evolution from shared to switched networks
Factors stressing capabilities of traditional (shared) LANS:
Faster CPUs
Faster Operating Systems
Network-intensive applications

6. Simple LAN switch

7. Benefits of switching
Bandwidth (not shared)
VLANs
Security

8. 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 don’t – can create broadcast storm
Routers create separate broadcast domains
Switches don’t have network (host) addresses, routers do.
Routers modify destination’s physical (not network) address

10. Switching vs Routing

11. Reliability (Fault-Tolerance) Mechanisms
Layer 2 - STP (Spanning Tree Protocol IEEE 802.1D (newer protocols include RSTP and MSTP)

12. Spanning Tree Port States

13. Reliability (Fault-Tolerance) Mechanisms
Layer 3 – VRRP and HSRP
A typical LAN

14. Reliability (Fault-Tolerance) Mechanisms
Layer 3 – VRRP and HSRP
HSRP addressing