Huawei Quidway NetEngine80E Configuration Manual page 881

HUAWEI NetEngine80E/40E Router
Configuration Guide - IP Routing
ipv4-family vpn-instance vpn-instance-name
The BGP-VPN instance IPv4 address family view is displayed.
Step 6 (Optional) Run:
peer { group-name | ipv4-address } bfd { min-tx-interval min-tx-interval | min-rx-
interval min-rx-interval | detect-multiplier multiplier | wtr wtr-value }
BFD session parameters are modified.
The default interval for transmitting BFD packets and the default detection multiplier are
recommended. When changing the default values, pay attention to the network status and the
network reliability requirement. A short interval for transmitting BFD packets can be configured
for a link that has a higher reliability requirement. A long interval for transmitting BFD packets
can be configured for a link that has a lower reliability requirement.
wtr wtr-value can be specified in the command to suppress frequent BFD and BGP session
flapping caused by link flapping. If a BFD session over a link goes Down, it does not go Up
immediately after the link recovers. Instead, the BFD session waits for the WTR timer to expire
before going Up. If the link fails again before the WTR timer expires, BFD does not send a link
fault message to BGP, and the BGP session status is stabilized.
The default value of wtr-value is 0, which means that the WTR timer will not be started.
Step 7 Run:
peer { group-name | ipv4-address } bfd enable [ single-hop-prefer ]
Issue 02 (2014-09-30)
NOTE
BFD for BGP can be configured for the VPN in this view. To configure BFD for BGP for the public
network, skip this step.
NOTE
The BFD parameters of peers take precedence over those of peer groups. If BFD parameters are configured
on peers, they will be used in BFD session establishment.
NOTE
There are three formulas: Actual interval for the local device to send BFD packets = max {Locally
configured interval for transmitting BFD packets, Remotely configured interval for receiving BFD
packets}, Actual interval for the local device to receive BFD packets = max {Remotely configured interval
for transmitting BFD packets, Locally configured interval for receiving BFD packets}, and Local detection
period = Actual interval for receiving BFD packets x Remotely configured BFD detection multiplier.
For example:
l On the local device, the configured interval for transmitting BFD packets is 200 ms, the interval for
receiving BFD packets is 300 ms, and the detection multiplier is 4.
l On the peer device, the configured interval for transmitting BFD packets is 100 ms, the interval for
receiving BFD packets is 600 ms, and the detection multiplier is 5.
Then:
l On the local device, the actual interval for transmitting BFD packets is 600 ms calculated by using the
formula max {200 ms, 600 ms}; the interval for receiving BFD packets is 300 ms calculated by using
the formula max {100 ms, 300 ms}; the detection period is 1500 ms calculated by multiplying 300 ms
by 5.
l On the peer device, the actual interval for transmitting BFD packets is 300 ms calculated by using the
formula max {100 ms, 300 ms}; the interval for receiving BFD packets is 600 ms calculated by using
the formula max {200 ms, 600 ms}; the detection period is 2400 ms calculated by multiplying 600 ms
by 4.
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8 BGP Configuration
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