Huawei AR550 Series - Page 301

Preemption Mode Description
Preemption Mode
NOTE
Preemption can only be
implemented on the device
where the primary edge
interface or no-neighbor
primary edge interface resides.
Preemption is classified into delayed preemption and
manual preemption.
l Delayed preemption
After all the faulty interfaces recover, the edge
interfaces no longer receive fault notification
packets. If the primary edge interface does not
receive fault advertisement packets within 3 seconds,
it starts the delay timer. After the delay timer expires,
nodes in the SEP segment start blocked interface
preemption.
l Manual preemption
When the link status databases of the primary edge
interface and secondary edge interface are complete,
the primary edge interface or brother interface of the
no-neighbor primary edge interface sends
preemption packets to block a specified interface.
The specified interface then sends blocking status
packets to request the previously blocked interface
to transition to the Forwarding state.
NOTE
Only two interfaces on a device can be added to the same
SEP segment. If one interface is the no-neighbor primary
edge interface, the other interface is the brother interface
of the no-neighbor primary edge interface.
Whether the brother interface of the no-neighbor primary
edge interface needs to send preemption packets depends
on whether the brother interface is blocked.
l If the brother interface is blocked, it does not need to
send preemption packets.
l If the brother interface is unblocked, it needs to send
preemption packets.
SEP Topology Change Notification
SEP considers that the topology of a SEP-enabled network changes in either of the following
situations described in Table 8-7.
Huawei AR530&AR550 Series Industrial Switch Routers
Configuration Guide - Ethernet Switching
8 SEP Configuration
Issue 01 (2014-11-30) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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