156CHAPTER 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

Loopback interface configuration includes:

Interface

Create the loopback interface

 

Configure operating parameters of the interfacE

1Create loopback interface

Table 187 Create/delete loopback interface

Operation

Command

 

 

Create the loopback interface and enter loopback

interface loopback number

interface view

 

 

 

Delete the specified loopback interface

undo interface loopback

 

number

 

 

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.

Table 188 Create/Delete Null interface:

Operation

Command

 

 

Create the Null interface and enter Null interface view

interface null 0

 

 

Delete the Null interface

undo interface null 0

 

 

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3Com 10014299 manual Configure Loopback, Null Interface