ATM Cable Interface Processor (ACIP) Installation and Configuration 25
Configuring the ACIP
Monitor and Maintain the ACIP
After configuring the new interface, you can display its status. You can also display the current status
of connections and active modems on each interface. To show current status information, perform
the following tasks in EXEC mode:
Configuration Example
This section contains an example that shows how to configure the ACIP interface; it also shows other
Cisco IOS commands required for the ACIP to connect to a cable headend (modem).
Each ATM virtual circuit carries data for a single subscriber cable data modem. Data sent over this
interface is first encapsulated in Ethernet frames and then encapsulated in AAL5 CPCS-PDU (per
RFC 1483 LLC SNAP Encapsulation of Bridged Protocols). To support encapsulation, the router
must operate as an integrated router/bridge by using the bridge irb command and the bridge-group
virtual interface (interface bvi command). The bridge-group virtual interface decapsulates the
Ethernet packets received from the ATM interface and multiplexes the router interface to multiple
VCs. No actual bridging is performed between VCs.
All of the IP devices on each of the Ethernet interfaces of the subscriber cable data modem must be
on the same IP subnet. The router, in general, will not perform an ARP to find MAC addresses of
hosts; instead, the router will assume that DHCP is used by each host. Because entries in the ARP
table must not age out normally, the software automatically adds the bridge number aging-time
604800 command to the configuration file.
Data from one host to another on the same cable channel must be sent via the router. The router
knows that two hosts are both on the same subnet and would normally send an ICMP redirect to
inform the first host that a better path exists. However, because the cable media does not support
direct host-to-host communications, the router must do the forwarding, and the ICMP must be
suppressed with the no ip redirects command.
The cable bind command specifies the headend IP address (1.1.1.2), and the BVI interface specifies
the local IP address (1.1.1.1).
Router(config)# interface atm 5/0
Router(config-if)# bridge-group 1
Router(config-if)# bridge-group 1 spanning-disable
Router(config-if)# no shutdown
Router(config-if)# exit
Router(config)# cable bind atm 5/0 17 1.1.1.2
Router(config)# bridge irb
Router(config)# interface bvi 1
Router(config-if)# ip address 1.1.1.1 255.255.255.0
Router(config-if)# no ip redirects
Router(config-if)# exit
Router(config)# bridge 1 protocol dec
Router(config)# bridge 1 route ip
Router(config)# exit
Task
Command
Display the configured cable channels status.
show cable channel
Display the active modems.
show cable modem
Display the ATM interface status.
show interface atm slot/number
Display the BVI interface status.
show interface bvi slot/number
