Operation of bfd – H3C Technologies H3C SR8800 User Manual
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Operation of BFD
Figure 29 BFD session establishment (on OSPF routers)
BFD session establishment:
1.
A protocol sends Hello messages to discover neighbors and establish neighborships.
2.
After establishing neighborships, the protocol notifies BFD of the neighbor information, including
destination and source addresses.
3.
BFD uses the information to establish BFD sessions.
Figure 30 BFD fault detection (on OSPF routers)
BFD fault detection (as shown in the above figure):
4.
BFD detects a link failure.
5.
BFD clears the neighbor session.
6.
BFD notifies the protocol of the failure.
7.
The protocol terminates the neighborship on the link.
8.
If a backup link is available, the protocol will use it to forward packets.
NOTE:
No detection time resolution is defined in the BFD draft. Most devices supporting BFD provide detection
measured in milliseconds.