156 CHAPTER 11: CONFIGURING LOGICAL INTERFACE
Some applications (such as configuring local peer of SNA) requires that a local
interface with specified IP address should be configured without affecting physical
interface configuration. Furthermore, this address should have a 32-bit mask to
reduce the use of IP addresses and it should be advertised by the routing
protocols. Therefore, the loopback interface is added to meet this requirement.
Configure Loopback
Interface Loopback interface configuration includes:
■Create the loopback interface
■Configure operating parameters of the interfacE
1Create loopback interface
Tabl e 187 Create/delete loopback interface
2Configure operating parameters on the interface
The parameters such as IP address and IP routing can be configured on loopback
interface. For detailed configuration, refer to Operation Manual – Network
Protocol.
The 32-bit mask can be configured for the loopback interface, that is, the mask
can be 255.255.255.255. The IP address with this 32-bit mask can be advertised
by the routing protocols.
When configuring the ip address of loopback interface, it is recommended to
configure the 32bit mask to save the ip address.
Null Interface The 3Com Router support Null interface. Null interface is always in UP status, but
cannot forward data packet or configure IP address or encapsulate other
protocols.
Null interface is a virtual interface. Any network data packet sent to this interface
will be dropped.
Configure Null Interface Null interface configuration includes:
■Create the Null interface
■Configure operating parameters of the interface
1Create the Null interface
Only one interface Null 0 can be created on the 3Com Router. Please perform the
following configurations in all views.
Tabl e 188 Create/Delete Null interface:
Operation Command
Create the loopback interface and enter loopback
interface view interface loopback number
Delete the specified loopback interface undo interface loopback
number
Operation Command
Create the Null interface and enter Null interface view interface null 0
Delete the Null interface undo interface null 0