FAQ-Differences Between and Roles of Link BFD and Peer BFD in VRRP Track BFD on the ME60s Used for Hot Backup

Publication Date:  2012-07-27 Views:  250 Downloads:  0
Issue Description
 Q:
In ME60 V100R006C05, in the configuration of VRRP track BFD, link BFD and peer BFD are different.
[ME60-GigabitEthernet3/0/0]vrrp vrid 255 track bfd-session 1 ?
link Specify link BFD
peer Specify peer BFD 

 
Alarm Information
 Null 

 
Handling Process
 A:
This configuration applies to the networking scenario in which two ME60s are connected to a downstream switch.
ME60-1 ME60-2
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\ /
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LSW
Link BFD refers to the BFD from the ME60 to the downstream switch.
Peer BFD refers to the BFD from the downstream interface on ME60-1 to the switch and then to the downstream interface on ME60-2.
With both link BFD and peer BFD, the ME60 can detect the point where a fault occurs. If link BFD and peer BFD are both Down on an ME60, it indicates that the fault occurs between this ME60 and the switch, and the VRRP status on this ME60 cannot be changed to Master. If link BFD is Up whereas peer BFD is Down on an ME60, it indicates that the fault occurs between its peer and the switch, and as a result the VRRP status on the local ME60 remains to be Master.
With link BFD and peer BFD, the ME60 can determine whether to change its VRRP status. This can prevent the existence of two VRRP masters and reduce the impacts of faults on services.
One primary purpose in adding link BFD and peer BFD to the configuration of VRRP track BFD is to prevent two ME60s that are configured for hot backup from being Masters at the same time. If the VRRP status on the two ME60s is Up at the same time, the backup will be in a mess, the users may fail to go online, and the return route will be abnormal. 

 
Root Cause
 Null 

 
Suggestions
 Null 

 

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