Zte ZXR10 8900E series, Описание продукта

Страница: 60 / 132

ZXR10 8900E series Core Switch Product Description
50 © 2013ZTE CORPORATION. All rights reserved. ZTE Confidential Proprietary
diagnosis frame, active equipment will consider that the ring goes wrong and
unlocks standby port to assure ring connectivity. Meanwhile, active equipment
refreshes L2 table and sends a notification frame to notify other ring equipments to
refresh their L2 tables. Ring monitoring mechanism is the backup of break alarm
mechanism. Once break alarm frame is lost for unknown reason, the solution is a
reliable backup support.
3. Ring restoration: When a ring link breaks, active equipment still periodically sends
diagnosis frame via active port, but standby port cannot receives it. After the ring
restores, the next diagnosis frame will be received by standby port of active
equipment. When active equipment receives diagnosis frame, it knows the ring
restores; then it sets standby port to blocked, refreshes L2 table and sends a
notification frame to notify other ring equipments to refresh their L2 tables. When
standby equipment detects that its connection restores, as diagnosis frame is
periodically sent, active equipment will not receive diagnosis frame immediately (so
standby port is unblocked). If no measure is taken now, standby port of active
equipment will remain unblocked for some time, which will result in temporary loop
and broadcast storm. To avoid the status, standby equipment needs to set the port
to be temporarily blocked when the port connection restores. When standby
equipment receives the notification frame from active equipment to refresh L2 table,
standby equipment knows that active equipment blocks its standby port, and then
standby equipment refreshes L2 table and unblock the restored port. Up to now the
ring returns to normal status.
3.7.4.2 ZESS
ZESS (ZTE Ethernet Smart Switching) technology fulfills fast switching protection and
load balance between L2 Ethernet links, and the active and standby links are switched
within 50ms. Its working principle is as shown in Figure 3-17: The node supports ZESS;
port 1 is active port and port 2 is standby port. When the node detects that active and
standby ports are UP, it blocks the protection service VLAN forwarding function of
standby port; when the node detects that active port is DOWN, it blocks the protection
service VLAN forwarding function of active port and unblocks the protection service
VLAN forwarding function of standby port; when the node detects that active port restores
to UP, it adopts inverse and non-inverse modes. In inverse mode, it unblocks active port
and blocks standby port again. In non-inverse mode, active port remains blocked and
standby port unblocked. In addition, in ZESS switching, it is required to upgrade FDB of
the blocked port.