Juniper JUNOSE SOFTWARE 11.0.X - BROADBAND ACCESS CONFIGURATION GUIDE 4-1-2010 Configuration Manual page 664

JUNOSe 11.0.x Broadband Access Configuration Guide
interface loopback
BEST PRACTICE: We recommend that you configure a 32-bit subnet mask for the
loopback interface. For example, if you configure a loopback interface with the IP
address and mask as 1.1.1.1/16, the 1.1.0.0/16 route entry is entered on the line
module and all traffic destined to the to 1.1.0.0/16 subnet is forwarded to the SRP
module by the line module. Although the SRP module responds only to traffic destined
to the 1.1.1.1 subnet and discards traffic to all other host IP addresses within that
subnet (1.1.1.1/16), if no specific or longer route entry is found or if the SRP module
receives too much traffic from subnets other than 1.1.1.1, the CPU utilization on the
SRP module reaches the saturation level.
If you use a subnet mask other than a /32 mask for the IP address configured on the
loopback interface, traffic from the entire subnet is routed to the loopback interface.
Therefore, that subnet cannot be routed through any other interface on the router,
unless a more specific route points to another interface.
ip address
624
Configuring Dynamic Subscriber Interfaces
Example
host1(config)#interface tenGigabitEthernet 4/0/1
Use the no version to remove IP from an interface. You must issue the no version
from the highest level down; you cannot remove an interface or subinterface if
the one above it still exists.
See interface tenGigabitEthernet
Use to access and configure a loopback interface.
You can use a loopback interface to provide a stable IP address that can minimize
the impact if a physical interface goes down.
You cannot shut down a loopback interface.
Example
host1(config)#interface loopback 10
host1(config-if)#ip address 10.20.32.1 255.255.255.255
Use the no version to delete the loopback interface.
See interface loopback
Use to set an IP address for an interface or a subinterface.
Specify the layer 2 encapsulation before you set the IP address.
Issuing this command creates the primary IP interface. You must create a primary
IP interface on which to enable dynamic creation of subscriber interfaces.
Example
host1(config-subif)#ip address 192.168.2.50 255.255.255.0