Scott Empson is an instructor in the Department of Information Systems Technology at the Northern Alberta Institute of Technology in Edmonton, Alberta, Canada, where he has taught for over 21 years. He teaches technical courses in Cisco routing and switching, along with courses in professional development and leadership. Scott created the CCNA Command Quick Reference in 2004 as a companion guide to the Cisco Networking Academy Program, and this guide became the CCNA Portable Command Guide in 2005. Other titles in the series in the areas of CCNP, Wireless, Security, Microsoft, and Linux followed beginning in 2006.

Scott has a Master of Education degree along with three undergraduate degrees: a Bachelor of Arts, with a major in English; a Bachelor of Education, again with a major in English/language arts; and a Bachelor of Applied Information Systems Technology, with a major in network management.

Patrick Gargano has been an educator since 1996, a Cisco Networking Academy Instructor since 2000, and a Certified Cisco Systems Instructor (CCSI) since 2005. He is currently based in Australia, where he is a Content Development Engineer at Skyline ATS, responsible for CCNP Enterprise course development with Learning@Cisco. He previously led the Networking Academy program at College La Cite in Ottawa, Canada, where he taught CCNA/CCNP-level courses, and he has also worked for Cisco Learning Partners Fast Lane UK, ARP Technologies, and NterOne.

In 2018 Patrick was awarded the Networking Academy Above and Beyond Instructor award for leading CCNA CyberOps early adoption and instructor training in Quebec, Canada. Patrick has also twice led the Cisco Networking Academy Dream Team at Cisco Live US.

Patrick’s previous Cisco Press publications include the CCNP Routing and Switching Portable Command Guide (2014) and 31 Days Before Your CCNA Security Exam (2016). His certifications include CCNA (R&S), CCNA Wireless, CCNA Security, CCNA CyberOps, and CCNP (R&S). He holds Bachelor of Education and Bachelor of Arts degrees from the University of Ottawa, and is completing a Master of Professional Studies in Computer Networking at Fort Hays State University (Kansas).

Introduction xix
PART I: LAYER 2 INFRASTRUCTURE
Chapter 1 VLANs 1
Virtual LANs 1
Creating Static VLANs Using VLAN Configuration Mode 2
Assigning Ports to Data and Voice VLANs 2
Using the range Command 3
Dynamic Trunking Protocol (DTP) 3
Setting the Trunk Encapsulation and Allowed VLANs 4
VLAN Trunking Protocol (VTP) 5
Verifying VTP 6
Verifying VLAN Information 7
Saving VLAN Configurations 7
Erasing VLAN Configurations 7
Configuration Example: VLANs 8
Layer 2 Link Aggregation 11
Interface Modes in EtherChannel 12
Default EtherChannel Configuration 12
Guidelines for Configuring EtherChannel 12
Configuring Layer 2 EtherChannel 14
Configuring Layer 3 EtherChannel 14
Configuring EtherChannel Load Balancing 15
Configuring LACP Hot-Standby Ports 16
Monitoring and Verifying EtherChannel 17
Configuration Example: EtherChannel 18
Chapter 2 Spanning Tree Protocol 23
Spanning Tree Protocol Definition 24
Enabling Spanning Tree Protocol 24
Changing the Spanning-Tree Mode 25
Configuring the Root Switch 25
Configuring a Secondary Root Switch 26
Configuring Port Priority 26
Configuring the Path Cost 27
Configuring the Switch Priority of a VLAN 27
Configuring STP Timers 27
Configuring Optional Spanning-Tree Features 28
PortFast 28
BPDU Guard (2xxx/older 3xxx Series) 29
BPDU Guard (3650/9xxx Series) 29
BPDU Filter 30
UplinkFast 30
BackboneFast 31
Root Guard 31
Loop Guard 32
Unidirectional Link Detection 33
Configuring and Verifying Port Error Conditions 33
Enabling Rapid Spanning Tree 36
Rapid Spanning Tree Link Types 36
Enabling Multiple Spanning Tree 37
Verifying the Extended System ID 39
Verifying STP 39
Troubleshooting Spanning Tree Protocol 40
Configuration Example: PVST+ 40
Spanning-Tree Migration Example: PVST+ to Rapid-PVST+ 43
Chapter 3 Implementing Inter-VLAN Routing 45
Inter-VLAN Communication Using an External Router: Router-on-a-Stick 45
Inter-VLAN Communication Tips 46
Inter-VLAN Communication on a Multilayer Switch Through a Switch Virtual Interface 46
Configuring Inter-VLAN Communication on an L3 Switch 47
Removing L2 Switchport Capability of an Interface on an L3 Switch 47
Configuration Example: Inter-VLAN Communication 47
Configuration Example: IPv6 Inter-VLAN Communication 55

PART II: LAYER 3 INFRASTRUCTURE
Chapter 4 EIGRP 61
Enhanced Interior Gateway Routing Protocol (EIGRP) 62
Enabling EIGRP for IPv4 Using Classic Mode Configuration 62
Enabling EIGRP for IPv6 Using Classic Mode Configuration 63
EIGRP Using Named Mode Configuration 64
EIGRP Named Mode Subconfiguration Modes 66
Upgrading Classic Mode to Named Mode Configuration 66
EIGRP Router ID 67
Authentication for EIGRP 67
Configuring Authentication in Classic Mode 67
Configuring Authentication in Named Mode 68
Verifying and Troubleshooting EIGRP Authentication 70
Auto-Summarization for EIGRP 70
IPv4 Manual Summarization for EIGRP 70
IPv6 Manual Summarization for EIGRP 71
Timers for EIGRP 71
Passive Interfaces for EIGRP 72
Pseudo Passive EIGRP Interfaces 72
Injecting a Default Route into EIGRP: Redistribution of a Static Route 73
Injecting a Default Route into EIGRP: ip default-network 74
Injecting a Default Route into EIGRP: Summarize to 0.0.0.0/0 74
Accepting Exterior Routing Information: default-information 75
Equal-cost Load Balancing: maximum-paths 75
Unequal-cost Load Balancing: variance 76
EIGRP Traffic Sharing 76
Bandwidth Use for EIGRP 77
Stub Routing for EIGRP 77
EIGRP Unicast Neighbors 79
EIGRP Wide Metrics 79
Adjusting the EIGRP Metric Weights 80
Verifying EIGRP 80
Troubleshooting EIGRP 82
Configuration Example: EIGRP for IPv4 and IPv6 Using Named Mode 83
Chapter 5 OSPF 87
Comparing OSPFv2 and OSPFv3 88
Configuring OSPF 89
Configuring Multiarea OSPF 89
Using Wildcard Masks with OSPF Areas 90
Configuring Traditional OSPFv3 91
Enabling OSPF for IPv6 on an Interface 91
OSPFv3 and Stub/NSSA Areas 92
Interarea OSPFv3 Route Summarization 92
Enabling an IPv4 Router ID for OSPFv3 93
Forcing an SPF Calculation 93
OSPFv3 Address Families 93
Configuring the IPv6 Address Family in OSPFv3 94
Configuring the IPv4 Address Family in OSPFv3 94
Applying Parameters in Address Family Configuration Mode 94
Authentication for OSPF 95
Configuring OSPFv2 Authentication: Simple Password 95
Configuring OSPFv2 Cryptographic Authentication: SHA-256 96
Configuring OSPFv3 Authentication and Encryption 97
Verifying OSPFv2 and OSPFv3 Authentication 98
Optimizing OSPF Parameters 98
Loopback Interfaces 98
Router ID 99
DR/BDR Elections 99
Passive Interfaces 100
Modifying Cost Metrics 100
OSPF Reference Bandwidth 101
OSPF LSDB Overload Protection 101
Timers 101
IP MTU 102
Propagating a Default Route 102
Route Summarization 103
Interarea Route Summarization 103
External Route Summarization 103
OSPF Route Filtering 104
Using the filter-list Command 104
Using the area range not-advertise Command 104
Using the distribute-list in Command 104
Using the summary-address not-advertise Command 105
OSPF Special Area Types 105
Stub Areas 105
Totally Stubby Areas 106
Not-So-Stubby Areas (NSSA) 106
Totally NSSA 107
Virtual Links 108
Configuration Example: Virtual Links 108
Verifying OSPF Configuration 109
Troubleshooting OSPF 111
Configuration Example: Single-Area OSPF 111
Configuration Example: Multiarea OSPF 114
Configuration Example: Traditional OSPFv3 117
Configuration Example: OSPFv3 with Address Families 120
Chapter 6 Redistribution and Path Control 127
Defining Seed and Default Metrics 128
Redistributing Connected Networks 129
Redistributing Static Routes 129
Redistributing Subnets into OSPF 130
Assigning E1 or E2 Routes in OSPF 130
Redistributing OSPF Internal and External Routes 131
Configuration Example: Route Redistribution for IPv4 131
Configuration Example: Route Redistribution for IPv6 132
Verifying Route Redistribution 134
Route Filtering Using the distribute-list Command 134
Configuration Example: Inbound and Outbound Distribute List Route Filters 134
Configuration Example: Controlling Redistribution with Outbound Distribute Lists 135
Verifying Route Filters 136
Route Filtering Using Prefix Lists 137
Configuration Example: Using a Distribute List That References a Prefix List to Control Redistribution 139
Verifying Prefix Lists 140
Using Route Maps with Route Redistribution 140
Configuration Example: Route Maps 141
Manipulating Redistribution Using Route Tagging 142
Changing Administrative Distance 143
Path Control with Policy-Based Routing 144
Verifying Policy-Based Routing 145
Configuration Example: PBR with Route Maps 146
Cisco IOS IP SLA 147
Configuring Authentication for IP SLA 149
Monitoring IP SLA Operations 150
PBR with Cisco IOS IP SLA 150
Step 1: Define Probe(s) 151
Step 2: Define Tracking Object(s) 152
Step 3a: Define the Action on the Tracking Object(s) 152
Step 3b: Define Policy Routing Using the Tracking Object(s) 152
Step 4: Verify IP SLA Operations 152
Chapter 7 BGP 155
Configuring BGP: Classic Configuration 156
Configuring Multiprotocol BGP (MP-BGP) 157
Configuring BGP: Address Families 158
Configuration Example: Using MP-BGP Address Families to Exchange IPv4 and IPv6 Routes 159
BGP Support for 4-Byte AS Numbers 160
BGP Timers 161
BGP and update-source 161
IBGP Next-Hop Behavior 162
EBGP Multihop 162
Attributes 164
Route Selection Decision ProcessThe BGP Best Path Algorithm 164
Weight Attribute 164
Using AS Path Access Lists to Manipulate the Weight Attribute 166
Using Prefix Lists and Route Maps to Manipulate the Weight Attribute 166
Local Preference Attribute 167
Using AS Path Access Lists with Route Maps to Manipulate the Local Preference Attribute 167
AS Path Attribute Prepending 169
AS Path: Removing Private Autonomous Systems 171
Multi-Exit Discriminator (MED) Attribute 171
Verifying BGP 174
Troubleshooting BGP 175
Default Routes 177
Route Aggregation 177
Route Reflectors 177
Regular Expressions 178
Regular Expressions: Examples 179
BGP Route Filtering Using Access Lists and Distribute Lists 180
Configuration Example: Using Prefix Lists and AS Path Access Lists 181
BGP Peer Groups 182
Authentication for BGP 184
Configuring Authentication Between BGP Peers 184
Verifying BGP...