H3C Technologies H3C S5560 Series Switches - Manual (Page 277)

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Enabling logging of session state changes
Perform this task to enable BGP to log BGP session establishment and disconnection events. To view the
log information, use the display bgp peer ipv4 unicast log-info command or the display bgp peer ipv6
unicast log-info command. The logs are sent to the information center. The output rules of the logs
(whether to output the logs and where to output) are determined by the information center configuration.
For more information about information center configuration, see Network Management and Monitoring
Configuration Guide.
To enable the logging of session state changes:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter BGP view. bgp as-number N/A
3. Enable the logging of session
state changes globally.
log-peer-change
By default, logging of session state
changes is enabled globally.
Configuring BFD for BGP
IMPORTANT:
If you have enabled GR, use BFD with caution because BFD might detect a failure before the system
performs GR, which will result in GR failure. If you have enabled both BFD and GR for BGP, do not disable
BFD during a GR process to avoid GR failure.
BGP maintains neighbor relationships based on the keepalive timer and hold timer in seconds. It requires
that the hold time must be at least three times the keepalive interval. This mechanism slows down link
failure detection. Once a failure occurs on a high-speed link, a large quantity of packets will be dropped
before routing convergence completes. BFD for BGP can solve this problem by fast detecting link failures
to reduce convergence time.
For more information about BFD, see High Availability Configuration Guide.
Before you can enable BFD for the BGP peer, establish a BGP session between the local router and the
peer.
To enable BFD for a BGP peer (IPv4):
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter BGP view or BGP-VPN
instance view.
• Enter BGP view:
bgp as-number
• Enter BGP-VPN instance view:
a. bgp as-number
b. ip vpn-instance vpn-instance-name
N/A
3. Enable BFD to detect the link to the
specified BGP peer. peer ip-address [ mask-length ] bfd
[ multi-hop | single-hop ] By default, BFD is
not enabled.