The document discusses switching in enterprise networks. It compares different types of switches used, including hardware-based layer 2 switches and software-based multilayer switches. It explains how spanning tree protocol prevents switching loops by blocking redundant links. It also describes how to configure and maintain VLANs on Cisco switches, including assigning ports, configuring trunking between switches, and using the VLAN Trunking Protocol to manage VLANs across the network. Inter-VLAN routing is enabled using a layer 3 device with subinterfaces.

1. Switching in an
Enterprise Network
Introducing Routing and Switching in the Enterprise –
Chapter 3
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2. Objectives
 Compare the types of switches used in an enterprise
network.
 Explain how Spanning Tree Protocol prevents
switching loops.
 Describe and configure VLANs on a Cisco switch.
 Describe and configure trunking and Inter-VLAN
routing.
 Maintain VLANs in an enterprise network.
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3. Compare the Types of Switches Used in an
Enterprise Network
 Switching and network segmentation
 Content addressable memory (CAM)
 Virtual circuits
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4. Compare the Types of Switches Used in an
Enterprise Network
 Hardware-based Layer 2 switching
 Software-based Layer-3 (multilayer) switching
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5. Compare the Types of Switches Used in an
Enterprise Network
 Store and forward switching
 Cut-through switching
Fast-forward
Fragment-free
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6. Compare the Types of Switches Used in an
Enterprise Network
 Switch physical security
 Switch access security
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7. Explain How Spanning Tree Protocol Prevents
Switching Loops
 Redundancy in network equipment
 Redundant network links
 Dangers of switching loops
 Broadcast storms
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8. Explain How Spanning Tree Protocol Prevents
Switching Loops
 Create a loop-free logical topology
 Potential loop detection and port blocking
 Redundancy without switching loops
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9. Explain How Spanning Tree Protocol Prevents
Switching Loops
 Determining a root bridge
 Bridge ID (BID)
 Root ports, designated ports, and blocked ports
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10. Explain How Spanning Tree Protocol Prevents
Switching Loops
 STP recalculations
 Minimizing downtime
PortFast
UplinkFast
BackboneFast
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11. Explain How Spanning Tree Protocol Prevents
Switching Loops
 Spanning-tree verification commands
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12. Explain How Spanning Tree Protocol Prevents
Switching Loops
 Rapid Spanning Tree Protocol
 Discarding
 Active topology
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13. Describe and Configure VLANs on a Cisco
Switch
 Virtual LANs
 Logical networks
 Broadcast control
 Transparent to end-users
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14. Describe and Configure VLANs on a Cisco
Switch
 VLAN functions
 VLAN membership
Static
Dynamic
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15. Describe and Configure VLANs on a Cisco
Switch
 VLAN 1: management VLAN
 VLAN numbers and names
 Port assignment
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16. Describe and Configure VLANs on a Cisco
Switch
 VLAN verification commands
 Deleting a VLAN
 Removing a port from a VLAN
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17. Describe and Configure VLANs on a Cisco
Switch
 VLAN ID
 Frame tagging: IEEE 802.1Q
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18. Describe and Configure Trunking and Inter-
VLAN Routing
• Trunk port characteristics
Point-to-point link
Carry multiple-VLAN traffic over single link
• Support for frame tagging
• Trunk modes
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19. Describe and Configure Trunking and Inter-
VLAN Routing
 Extending VLANs across switches
 Configuring a native VLAN
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20. Describe and Configure Trunking and Inter-
VLAN Routing
 Connectivity between different VLANs
 Subinterfaces
 Router-on-a-stick
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21. Maintain VLAN Structure on an Enterprise
Network
 VLAN Trunking Protocol (VTP) purpose and goals
 Management domain
 VTP modes: server, client, transparent
 VLAN database
 Configuration revision number
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22. Maintain VLAN Structure on an Enterprise
Network
 VTP messages
Summary advertisements
Subset advertisements
Advertisement requests
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23. Maintain VLAN Structure on an Enterprise
Network
 Configuring VTP
 Verifying VTP configuration
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24. Maintain VLAN Structure on an Enterprise
Network
 VLANs and IP phones
 VLANs and wireless security
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25. Maintain VLAN Structure on an Enterprise
Network
 VLAN best practices
 VLAN security
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26. Summary
 Switches forward traffic using store and forward or cut-through
techniques
 Basic security features should be applied to switches
 A VLAN is a way to group hosts on the same logical network even
though they may be physically separated
 Frame tagging allows a switch to identify the source VLAN of an
Ethernet frame.
 A Layer 3 device is needed to move traffic between different
VLANs.
 Subinterfaces allow router interfaces to support multiple VLANs.
 VLAN Trunking Protocol provides centralized control, distribution
and maintenance of VLANs.
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27. © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 27