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Voice, IP, and ATM MPLS Features

  • Sample Chapter is provided courtesy of Cisco Press.
  • Date: May 17, 2002.

Commands for Configuring Subinterfaces

This section describes the commands you use to create and configure subinterfaces on the RPM ATM switch interface:

  • show interface—Displays the status of a specific interface or all interfaces on the RPM.

  • interface—Creates or accesses the configuration of an interface or subinterface.

  • shutdown—Disables an interface or subinterface. The no shutdown command activates an interface.

  • ip address—Assigns an IP address and subnet mask to a subinterface.

Show Interface Command

The show interface command output lists detailed interface and subinterface configuration and status information. You can specify a particular interface. Otherwise, all interfaces are listed.

Here is the show interface command syntax:

show interface [switch <slot-number>/<interface-number>.[subinterface-number]]

The keyword and parameter options are as follows:

  • a keyword, all interfaces are listed.

  • slot-number—If you specify the switch keyword, you must specify the RPM card slot number.

  • interface-number—If you specify the switch keyword, you must specify the interface number. For the RPM switch interface, the only valid value is 1.

  • subinterface-number—You can also specify a subinterface number.

For example, type show interface 9/1.100 to list information for subinterface 100 on the ATM switch interface of the RPM in slot 9. Type show interface to list information for all interfaces on the RPM. Example 22-20 shows the show interface switch output for a subinterface.

Example 22-20 show interface switch Output

rpm01>sho int switch 9/1.100

Switch1.100 is up, line protocol is up
 Hardware is ENHANCED ATM PA
 Internet address is
 MTU 4470 bytes, BW 149760 Kbit, DLY 100 usec,
   reliability 255/255, txload 1/255, rxload 1/255
 Encapsulation ATM
 0 packets input, 0 bytes
 9 packets output,531 bytes
 0 OAM cells input, 0 OAM cells output

Useful information in the show interface switch output includes the following:

  • Interface status—Up or down

  • Line protocol status—Up or down

  • IP address

  • Maximum Transmission Size (MTU)—The largest packet size, in bytes, permitted on the interface

  • Bandwidth (BW)—The interface bandwidth in kbps

  • Encapsulation—Always ATM

  • Ingress and egress traffic counters

You can clear the traffic counters by using the clear counters switch command.

Interface Command

The interface global configuration command accesses interface-specific configuration mode. You also use the interface command to create a new subinterface.

When you use the interface command, the CLI prompt changes from hostname(config)# to hostname(config-if)#.

Here is the interface command syntax:

interface [switch <slot-number>/<interface-number>.[subinterface-number]]
  {point-to-point | multipoint | tag}

The keyword and parameter options are as follows:

  • switch—This optional keyword shows the switch interface.

  • slot-number—If you specify the switch keyword, you must specify the RPM card slot number.

  • interface-number—If you specify the switch keyword, you must specify the interface number. For the RPM switch interface, the only valid value is 1.

  • subinterface-number—You can also specify a subinterface number.

  • point-to-point—Creates a point-to-point subinterface that supports only one PVC. You need to specify this keyword only when you are creating a new subinterface.

  • multipoint—Creates a multipoint subinterface that supports multiple PVCs. You need to specify this keyword only when you are creating a new subinterface.

  • tag—Creates a tag (MPLS) subinterface. You need to specify this keyword only when you are creating a new subinterface.

Shutdown Command

The shutdown interface-specific configuration command deactivates an interface. Use the no shutdown command to activate an interface. By default, a subinterface is active when you create it using the interface command.

IP Address Command

The ip address interface-specific configuration command is used to assign an IP address to a subinterface.

Here is the ip address command syntax:

ip address <IP-address> <subnet-mask>

The parameter options are as follows:

  • IP-address—The IP address assigned to the subinterface. Remember when choosing an IP address that subinterfaces with PVCs between them must be on the same IP network. The IP address is entered in dotted-decimal format, such as

  • subnet-mask—The subnet mask used on the subinterface. Subinterfaces with PVCs between them should all be configured with the same subnet mask. The subnet mask is entered in dotted-decimal format, such as

27. Commands for Creating and Displaying PVCs on the RPM | Next Section Previous Section

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