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

1
Large-scale (Campus) Lan design (Part II)

• VLANs
• Hierarchical LAN design

2
Virtual LANs (VLANs)
3
Virtual LANs (VLANs)

• VLANs consist of end systems that are members of
  a single logical broadcast domain.
• A VLAN has no physical proximity constraints for
  the broadcast domain
• A VLAN can span various pieces of network
  equipment that support VLAN trunking protocols
  between them
• Without a router, hosts in 1 VLAN cant
  communicate with hosts in another VLAN

4
Single-switch VLANs
5
VLAN Benefits

• VLANs break networks into smaller broadcast
  domains
• VLANs provide security
• Easier network management
• Well-behaved VLANs usually follow 80/20 network
  design rule

6
VLAN Example
7
VLAN Trunking

• Trunk high-speed connection between
  internetworking devices
• Switches use Trunking protocol to exchange
  information about VLAN configuration (e.g. IEEE
  802.1Q, Ciscos ISL)
• With trunking, tags are added to all the frames
  traveling on the trunk

8
VLANs are shared through trunks
9
VLAN Implementation

• By port each port must belong to only 1 VLAN
• By protocol single port can support more than 1
  VLAN
• By a user-defined value e.g. MAC address

10
Single switch VLANs
11
Backbone

• Traditional
• Collapsed

12
Redundancy in the Backbone
13
Distributed backbone (multiple collapse points)
14
Hierarchical Design

• Access
• Distribution
• Core

15
Hierarchical Design
16
Central Routing
17
Distributed Routing
18
Small campus
19
Medium campus
20
Large campus