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Configuration Guide - Reliability

CloudEngine 12800 and 12800E V200R002C50

This document describes the configurations of Reliability, including BFD Configuration, VRRP Configuration, DLDP Configuration, Smart Link and Monitor Link Configuration, EFM Configuration, and CFM Configuration.
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A link failure or topology change may lead to route recalculation. Therefore, the convergence time of routing protocols must be as short as possible to ensure good network performance. A possible solution is to quickly detect link faults and immediately notify routing protocols of the faults.

BFD for OSPF associates a BFD session with OSPF. The BFD session quickly detects a link fault and notifies OSPF of the fault. OSPF quickly responds to the network topology change. Table 2-1 lists OSPF convergence time.

Table 2-1 OSPF convergence time

BFD Session

Link Fault Detection Mechanism

Convergence Time

Not bound

Timeout of the OSPF Hello keepalive timer

Measured in seconds


BFD session in Down state

Measured in milliseconds


Figure 2-6 BFD for OSPF

In Figure 2-6, SwitchA establishes OSPF neighbor relationships with SwitchC and SwitchD. The outbound interface in the route from SwitchA to SwitchB is Interface 1. Packets from SwitchA are sent to SwitchB through SwitchC. When the OSPF neighbor relationship is in Full state, the system instructs BFD to create a BFD session.

If a fault occurs on the link between SwitchA and SwitchC, the BFD session detects the fault and notifies SwitchA. SwitchA processes the neighbor Down event and recalculates the route. Interface 2 then becomes the new outbound interface in the route. Packets from SwitchA are sent to SwitchB through SwitchD.

Updated: 2019-03-21

Document ID: EDOC1000166606

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