1. LAN Switching and Wireless – Chapter 1 Vilina Hutter, Instructor
LAN Design
LAN Switching and Wireless – Chapter 1
Vilina Hutter, Instructor

2. Hierarchical Network Design
3 layered model
Access, Distribution, & Core Layers
Each layer has specific functions
Facilitates modularity
Modularity facilitates scalability and enhanced performance
In small networks, the core and distribution layers can be combined—known as the collapsed core model

3. Access Layer End user devices PCs, phones, printers
Access to network for users
Can include any networking device

4. Distribution Layer Controls the flow of network traffic
Policy implementation
Broadcast containment
VLAN connectivity
Switches and Routers

5. Core Layer
High-speed backbone
Routers or switches
Redundant links

6. Physical Layout of a Hierarchical Design
Less easy to see the hierarchical design layers in the physical layout!

7. Benefits of a Hierarchical Design
Use graphic
Use graphic

8. Four Design Principles
Network Diameter
Bandwidth Aggregation
Redundant Links
Start at the Access Layer!

9. Network Diameter
How many devices a packet must cross to reach its destination
Lower is better!

10. Bandwidth Aggregation
Combining several parallel links between two switches to form one logical link

11. Redundant Links
Used between devices at the core and distribution layer to ensure network availability

12. Start at the Access Layer!
Business needs are met at the access layer
All network design is driven by the needs of the business and its users
U.S.A.F’s Network Centric Collaborative Targeting (NCCT) system

13. Converged Networks Networks that carry video, data, and voice
Convergence has been slowed by installed analog phone infrastructure
Advantages of convergence:
One network to manage
One set of cabling
One ring to rule them all
Lower management costs
New technology options
Softphones, webcams
Videoconferencing

14. Selecting Network Devices
Traffic Flow Analysis
To select the right switches, network designers must accommodate present and projected network traffic requirements
Traffic flow analysis tools are available to track, record, and analyze traffic patterns on a network

15. User Communities Analysis
Consider the number of devices that need to join the network now and in the projected future
Switch port number planning
Consider any special traffic flow needs for particular applications used by a particular user community
If a community uses a traffic-intensive application, they should be located physically close to their server to reduce network diameter for the workers
Smaller diameter for HR Dept.

16. Data Stores and Data Servers Analysis
Examine traffic patterns between clients and their servers and between servers and data storage
Potential bottlenecks between clients and servers can be reduced by aggregating bandwidth and by installing powerful switches
High traffic volume between servers will have less impact on the entire network if the servers are physically close to each other
Typically, all servers are located in a secure data center
Distribution layer switches are also located in the data center

17. Topology Diagram Analysis
Careful examination of a detailed topology map will all identification of potential bottlenecks
Traffic flow analysis can then be focused on those likely problem spots

18. Switch Features Form Factor Performance PoE (Power over Ethernet)
Fixed or modular hardware configuration
Rack units (thickness)
Stackable vs. non-stackable
Performance
Port density
Forwarding rates
Bandwidth aggregation
PoE (Power over Ethernet)
Layer 3 Functionality

19. Match the Appropriate Cisco Switch to each Layer in the Hierarchical Network Design Model
Identify the considerations used to select a switch for a hierarchical network
Graphics from section pages 2 & 3

20. Form Factor—Fixed vs. Modular
Fixed configuration switches cannot be modified or upgraded
Modular switches accept line cards
Line cards contain the ports
Line cards can be added or upgraded
The larger the chassis, the more line cards can be supported

21. Form Factor--Stackable
Stackable switches can be connected by a backplane cable
Allows a group of switches to effectively act as one switch
Backplane cables use a special fast port to connect switches
Cross-connections allow for fast recovery if a single switch fails
Graphics found in section & 1.2.2

22. Match the Appropriate Cisco Switch to each Layer in the Hierarchical Network Design Model
Identify the switch features found in each level in a hierarchical network
Section – all of the graphics on pages 1-3 are good

23. Performance—Port Density
Number of ports available on a single switch
Higher port density is more efficient
Space considerations
Power outlets/consumption
Fixed switches support a maximum density of 48 ports
Modular switches support up to ports
If many fixed switches are installed, they must all be uplinked, consuming ports for link aggregation
Modular switches support the line port aggregation via the backplane

24. Performance—Forwarding Rates
How much total data the switch can forward per second
Especially at the distribution and core layers, the switch must support full speed on all port simultaneously
At the access layer, switches are limited by the uplink capability, so the forwarding rate is less crucial

25. Switch Performance—Link Aggregation
All switches should support link aggregation to avoid uplink bottlenecks

26. Switch Performance—PoE
PoE is the ability to provide electrical power to devices over the Ethernet ports
Particularly useful for IP phones or access points which may need to be located away from electrical power lines
PoE is an expensive feature, which should not be ordered unless needed

27. Switch Performance— Layer 3 Functionality
Known as multilayer switching
Supports routing function and security policy implementation

28. Access Layer Switch Features

29. Distribution Layer Switch Features
Distribution layer switches are typically implemented in pairs to ensure availability. It is also recommended that distribution layer switches support multiple, hot swappable power supplies

30. Core Layer Switch Features
Because of the high workload carried by core layer switches, they tend to operate hotter than access or distribution layer switches, so they should have more sophisticated cooling options. Many true, core layer-capable switches have the ability to swap cooling fans without having to turn the switch off.

31. Switch Model Selection
Use graphic

32. Summary
Hierarchical Design model addresses performance, scalability, maintainability & manageability issues.
Traffic Analysis is used to monitor network performance.
Hierarchical Design Model is composed of 3 layers:
Access
Distribution
Core
Switches selected for each layer must meet the needs of each hierarchical layer as well as the needs of the business.