5.1. Naming and Numbering Interfaces5.1.1. Subinterfaces5.2. Basic Interface Configuration Commands5.2.1. shutdown5.2.2. Interface Descriptions5.2.3. Setting the IP Address and Subnet Mask5.2.3.1. Secondary IP address(es)5.2.4. Other Common Interface Commands5.3. The Loopback Interface5.4. The Null Interface5.5. Ethernet, Fast Ethernet, and Gigabit Ethernet Interfaces5.6. Token Ring Interfaces5.7. ISDN Interfaces5.7.1. A Simple ISDN Configuration5.8. Serial Interfaces5.8.1. Serial Encapsulation5.8.2. Serial T1 Connection5.8.3. T1 Configuration on a 2524 with a CSU/DSU Card5.8.4. Channelized T15.9. Asynchronous Interfaces5.9.1. Using the group-async Command5.9.2. Specifying an IP Address Pool5.9.3. Using BOOTP Configuration Items for Dial-in Connections5.9.4. Using DHCP for IP Addresses and Dial-in Configuration Items5.10. Interface show Commands5.10.1. Clearing the show Command Counters5.10.2. Listing All Interfaces5.10.3. Using the show interface Commands5.10.3.1. show interface accounting5.10.3.2. show ip interface