19 S YSTEM-G UARD C ONFIGURATIONSystem-Guard Configuration 235Displaying and Maintaining the System-Guard Function 23620 AAA O VERVIEWIntroduction to AAA 237Introduction to AAA Services 23821 AAA C ONFIGURATIONAAA Configuration Task List 245RADIUS Configuration Task List 251Displaying and Maintaining AAA 262AAA Configuration Examples 263Troubleshooting AAA 26622 MAC A UTHENTICATION C ONFIGURATIONMAC Authentication Overview 269Related Concepts 270Configuring Basic MAC Authentication Functions 270MAC Address Authentication Enhanced Function Configuration 271Displaying and Debugging MAC Authentication 274MAC Authentication Configuration Example 27523 ARP C ONFIGURATIONIntroduction to ARP 277ARP Configuration 279Displaying and Debugging ARP 279ARP Configuration Example 28024 DHCP OVERVIEWIntroduction to DHCP 281DHCP IP Address Assignment 281DHCP Packet Format 283Protocol Specification 28425 DHCP SNOOPING C ONFIGURATIONIntroduction to DHCP Snooping 285DHCP Snooping Configuration 286DHCP Snooping Configuration Example 28626 DHCP/BOOTP C LIENT C ONFIGURATIONIntroduction to DHCP Client 287Introduction to BOOTP Client 287