1.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE I Chapter 6 1
Switching in an
Enterprise Network

2.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 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.

3.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 3
Compare the Types of Switches Used in an
Enterprise Network
 Switching and network segmentation
 Content addressable memory (CAM)
 Virtual circuits

4.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 4
Compare the Types of Switches Used in an
Enterprise Network
 Hardware-based Layer 2 switching
 Software-based Layer-3 (multilayer) switching

5.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 5
Compare the Types of Switches Used in an
Enterprise Network
 Store and forward switching
 Cut-through switching
Fast-forward
Fragment-free

6.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 6
Compare the Types of Switches Used in an
Enterprise Network
 Switch physical security
 Switch access security

7.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 7
Explain How Spanning Tree Protocol Prevents
Switching Loops
 Redundancy in network equipment
 Redundant network links
 Dangers of switching loops
 Broadcast storms

8.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 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

9.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 9
Explain How Spanning Tree Protocol Prevents
Switching Loops
 Determining a root bridge
 Bridge ID (BID)
 Root ports, designated ports, and blocked ports

10.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 10
Explain How Spanning Tree Protocol Prevents
Switching Loops
 STP recalculations
 Minimizing downtime
PortFast
UplinkFast
BackboneFast

11.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 11
Explain How Spanning Tree Protocol Prevents
Switching Loops
 Spanning-tree verification commands

12.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 12
Explain How Spanning Tree Protocol Prevents
Switching Loops
 Rapid Spanning Tree Protocol
 Discarding
 Active topology

13.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 13
Describe and Configure VLANs on a Cisco
Switch
 Virtual LANs
 Logical networks
 Broadcast control
 Transparent to end-users

14.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 14
Describe and Configure VLANs on a Cisco
Switch
 VLAN functions
 VLAN membership
Static
Dynamic

15.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 15
Describe and Configure VLANs on a Cisco
Switch
 VLAN 1: management VLAN
 VLAN numbers and names
 Port assignment

16.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 16
Describe and Configure VLANs on a Cisco
Switch
 VLAN verification commands
 Deleting a VLAN
 Removing a port from a VLAN

17.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 17
Describe and Configure VLANs on a Cisco
Switch
 VLAN ID
 Frame tagging: IEEE 802.1Q

18.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 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

19.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 19
 Extending VLANs across switches
 Configuring a native VLAN
Describe and Configure Trunking and Inter-
VLAN Routing

20.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 20
 Connectivity between different VLANs
 Subinterfaces
 Router-on-a-stick
Describe and Configure Trunking and Inter-
VLAN Routing

21.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 21
 VLAN Trunking Protocol (VTP) purpose and goals
 Management domain
 VTP modes: server, client, transparent
 VLAN database
 Configuration revision number
Maintain VLAN Structure on an Enterprise
Network

22.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 22
Maintain VLAN Structure on an Enterprise
Network
 VTP messages
Summary advertisements
Subset advertisements
Advertisement requests

23.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 23
 Configuring VTP
 Verifying VTP configuration
Maintain VLAN Structure on an Enterprise
Network

24.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 24
 VLANs and IP phones
 VLANs and wireless security
Maintain VLAN Structure on an Enterprise
Network

25.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 25
 VLAN best practices
 VLAN security
Maintain VLAN Structure on an Enterprise
Network

26.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 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.