Cisco Broadband Cable, Справочное руководство, Страница: 1011 / 1278

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Cisco Broadband Cable Command Reference Guide
OL-1581-07
Chapter 6 Cable CPE Commands
cable-modem dhcp-proxy
The reason is that the default router configuration is for DOCSIS-compliant bridging, which includes
two
bridge-group 59 commands for each interface. To use the cable-modem dhcp-proxy command,
you must put the router into routing mode, which means removing the bridge-group commands with the
equivalent no bridge-group commands.
However, because no bridge-group is the default for these CLI commands, they are not saved in the
running configuration. So when you save the Cisco IOS configuration file and copy it to other routers,
the router is only partially configured for routing mode and continually resets its interfaces.
In addition, whenever you use the cable-modem dhcp-proxy command to create a NAT pool, the router
automatically adds the appropriate ip nat pool commands to the configuration when it receives the actual
IP addresses from the DHCP server. The IP addresses specified in this command are particular to each
user and should not be copied to other routers.
To avoid this problem, use the following procedure to create a Cisco IOS configuration file that uses the
cable-modem dhcp-proxy command to create a NAT address pool for NAT/PAT address translation:
Step 1 Create and test a working configuration on a cable access router.
Step 2
After you have created a standardized configuration, save it to memory, and then copy the Cisco IOS
configuration file to the TFTP server that will be used to copy the file to the other routers.
Step 3 Open the Cisco IOS configuration file with a text editor and add the following lines underneath each
interface:
no bridge-group 59
no bridge-group 59 spanning-disabled
Step 4
Remove the ip nat pool command.
For example, the following are the relevant lines in a typical DHCP proxy NAT configuration for a cable
access router:
interface Ethernet0
ip address 192.168.1.1 255.255.255.0
ip nat inside
load-interval 30
!
interface cable-modem0
ip nat outside
load-interval 30
no cable-modem compliant bridge
cable-modem dhcp-proxy nat nat-pool
!
ip nat pool nat-pool 10.15.0.10 10.15.0.10 netmask 255.255.0.0
When you copy this configuration file to the TFTP server, modify this portion of the configuration file
to add the
no bridge-group commands under each interface and to remove the ip nat pool command:
interface Ethernet0
ip address 192.168.1.1 255.255.255.0
ip nat inside
load-interval 30
no bridge-group 59
no bridge-group 59 spanning-disabled
!
interface cable-modem0
ip nat outside
load-interval 30
no cable-modem compliant bridge