Campus LAN Overview

Objectives Identify the technical considerations in campus LAN design Identify the business considerations in campus LAN design Describe the evolutionary approach to campus LAN design

Campus LAN Technical Issues Campus Floor Building Floor Client end stations Server end stations Network infrastructure Network management

Client End-Station Issues Application support issues – Bandwidth demand – Quality of service Platform upgrades Network interface cards (NICs) Cable connectors Wiring Closet Wall plate Wall NIC

High-performance medium NIC Server End-Station Issues Application support issues – Bandwidth demand – Performance requirements Server placement Network interface card Cable connectors

Network Infrastructure Issues Backbone strategy – distributed or collapsed Bandwidth requirements Technology – Fast Ethernet / FDDI/ ATM/ Metro Ethernet Bridging (switching) vs routing

Campus LAN Design Evolution: Bridges and Routers Flat model for small workgroups Routers for large and mixed-media workgroups FDDI backbone with dual-homed routers for fault tolerance

Cable Plant Type Electrical – Coaxial – Twisted-pair Fiber-optic – Multimode – Single-mode Wiring configuration – Home run – Zoned – Distance limitations

Hub Hubs and Structured Cabling Category 5 to the desk Multimode fiber in the riser Hub

Network Management Issues Models – Centralized – Distributed Network management stations User administration –Moves, adds, and changes – Virtual LANs (VLANs) Network management tools – Capabilities – Bandwidth demands – RMON – Scope of support LAN WAN

Business Issues Budget -Preserving current investment -Cost of purchase -Cost of ownership Adhering to standards -Coporate -Industry Planning for growth

Client/Client Bandwidth Time Terminal/Host Alphanumeric Client/Server Graphical Video Campus LAN Design Evolution: New Network Applications

What’s potential problems Media contention Excessive broadcasts Protocols that do not scale well Need to transport new payloads Need for more bandwidth Overloaded backbone Network layer addressing issues Security concerns

Protocols MediaTransport Solving Network Problems

Media contention solved by lan switching Excessive broadcast (protocol related) solved by routing Payload require high bandwidth and predictable low latency, use ATM

Use Switches to Reduce Congestion Avoid congestion on a LAN by using microsegmentation Cascade switches and hubs Tailor availability to the needs of the device

Ethernet collision domain shared bandwidth Broadcasts are visible across subnets Bandwidth Domain versus Broadcast Domain

Broadcast Radiation Shared Multicast and Broadcast Bus Shared Data Bus Point-to-Point Data Bus Shared Multicast and Broadcast Bus Hub Switch Broadcast Filter

Use Routers for Scalable Internetworks Routers serve as broadcast firewalls Routers make clean media conversions Routers consolidate for scalable internetworks

Use Routers to Impose Logical Structure One router divides subnets and networks One router structures an internetwork

LAN switch LAN switch serves 2 functions : dedicated full LAN speed per port; support multiple concurrent transmission paths support bridging (now called layer 2 switching) ASIC based; frame switching by hardware high speed some switches can support layer 3 switching Store-and-forward or Cut-through modes

Layer 3 switch basically a high end LAN switch that can switch at L2 and route at L3 2 types of L3 switches packet by packet cut-through packet by packet L3 switch is essentially a trimmed down router; usually IP based only work like traditional software router

Virtual LAN (VLAN) logical groupings of workgroups in a switch work like physically separate LANs; collision and broadcast is contained within each VLAN simplify move, change and relocate need to internetwork through routers policy based : can be based on physical ports, MAC address or IP subnet can span across multiple switches proprietary; future standard 802.1Q tagging