Figure 5-38 Diagram Of The Master Node Opening Its Secondary Port When The Ring Is In Down State - Zte ZXR10 2900E series Configuration Manual

ZXR10 2900E Series Configuration Guide
Figure 5-38 Diagram of the Master Node Opening its Secondary Port When the Ring
is in DOWN State
As shown in Figure 5-37, all links operate properly, the ring is in UP state, the secondary
port of the master node is blocked, and traffic needs to go through switch C and switch D.
As shown in Figure 5-38, the link between switch B and switch C is disconnected, the ring
state is changed to DOWN, ZESR rapidly transits the secondary port of the master node
to Forwarding state, and traffic is switched quickly to switch A without going through switch
C and switch D.
When the link between switch B and switch C recovers from disconnection, the secondary
port of the master node is blocked again, the ring is switched to UP state, and the entire
ZESR region returns to the state shown in Figure 5-37.
link-hello Link Connectivity Detection Overview
Figure 5-39 shows the transmission link fault diagram. Switch C does not have a direct
connection with switch D. They are interconnected with each other through transmission
links.
When the transmission link marked in red in the middle of the transmission links
encounters a bidirectional connectivity failure, switch C and switch D are still in UP state.
If the bidirectional connectivity detection function is not enabled for the transmission link,
switch C and switch D will not be able to perceive this failure and for this reason ZESR
link switching will not be triggered.
If the link-hello link connectivity detection function is enabled on the ports through which
switch C and switch D are interconnected with each other, these ports will periodically send
link-hello detection packets to each other. If a port does not receive the link-hello detection
packet from the peer port within a specified time period, the switch will consider this as a
link failure. The device will immediately block the ports on the link and inform the master
node to implement link switching.
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SJ-20130731155059-002|2013-11-27 (R1.0) ZTE Proprietary and Confidential