H3C S9500E Series Configuration Manual page 171

Operation of BFD
Figure 42 BFD session establishment (on OSPF routers)
Router A
BFD session establishment (as shown in Figure 42):
•
A protocol sends hello messages to discover neighbors and establish neighborships.
•
After establishing neighborships, the protocol notifies BFD of the neighbor information,
including destination and source addresses.
•
BFD uses the information to establish BFD sessions.
Figure 43 BFD fault detection (on OSPF routers)
BFD fault detection (as shown in Figure 43):
•
Upon detection of a link failure, BFD clears the session and notifies the protocol of the
failure.
•
The protocol terminates the neighborship on the link.
•
If a backup link is available, the protocol will use it to forward packets.
No detection time resolution is defined in the BFD draft. At present, most switches supporting BFD provide
detection measured in milliseconds.
3
2
1
BFD neighbors
OSPF advertises the BFD neighbor relationship
2
Router B
OSPF neighbors
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