Setting an Interface Blocking Mode

Context

In a SEP segment, some interfaces are blocked to prevent loops.

You can configure the interface blocking mode to specify a blocked interface. Table 1 lists interface blocking modes.

**Table 1** Interface blocking mode
Interface Blocking Mode	Description
Specify the interface with the highest priority as the blocked interface.	This mode applies to a large-scale network. After fault recovery, the interface with the highest priority in a SEP segment becomes the blocked interface. In this mode, the priorities of the interfaces in the SEP segment need to be set in advance.
Specify the interface in the middle of a SEP segment as the blocked interface.	This mode applies to a network where traffic is symmetrically distributed. After fault recovery, the interface in the middle of a SEP segment becomes the blocked interface.
Specify a blocked interface based on the configured hop count.	This mode applies to a small-scale network. After fault recovery, a specified interface is blocked based on the hop count. A network planner needs to be familiar with the topology of the entire SEP segment and the number of hops from the blocked interface to the primary edge interface.
Specify a blocked interface based on the device and interface names.	This mode applies to a small-scale network. After fault recovery, a specified interface is blocked based on the device and interface names. A network planner needs to be familiar with the names of devices and interfaces in the entire SEP segment and ensures that each device name is unique.

Perform the following operations on the device where the primary edge interface or no-neighbor primary edge interface is located:

Procedure

Run system-view
The system view is displayed.
Run sep segment segment-id
A SEP segment is created and the view of the SEP segment is displayed.
Run block port { optimal | middle | hop hop-id | sysname sysname interface { interface-type interface-number | interface-name } }
An interface blocking mode is set.

By default, one of the interfaces at two ends of the link that is set up last or recovers from a fault last is blocked.

Follow-up Procedure

If the interface with the highest priority is specified to block, run the sep segment segment-id priority priority command in the view of the interface to be blocked to increase its priority. When a fault is rectified, the specified interface is blocked.

The default priority of an interface added to a SEP segment is 64. The priority value of an interface is an integer that ranges from 1 to 128. A larger priority value indicates a higher priority.