R3102-R3103-HP 6600/HSR6600 Routers Layer 3 - IP Routing Configuration Guide
239
routes already learned to complete BGP routing convergence. The GR Helper then removes the
state routes.
Follow these guidelines when you configure BGP GR:
• The GR and NSR features are mutually exclusive. Do not configure them at the same time.
• GR Restarter sends the maximum time allowed for the peer to reestablish a BGP session to the GR
Helper in an Open message. When the GR Helper detects that the session to the GR Restarter is
down, it waits until the time advertised by the GR Restarter expires for a new session to be
established.
• In general, the maximum time allowed for the peer to reestablish a BGP session must be less than
the Holdtime carried in the Open message.
• The End-Of-RIB (End of Routing-Information-Base) indicates the end of route updates.
• The maximum time to wait for the End-of-RIB marker configured on the local end is not advertised
to the peer; the setting is used to control the time on the local end to receive updates from the peer
end.
Perform the following configuration on the GR Restarter and GR Helper, respectively.
To configure BGP GR:
Ste
p
Command
Remarks
1. Enter system view.
system-view
N/A
2. Enable BGP, and enter its view.
bgp as-number N/A
3. Enable GR Capability for BGP.
graceful-restart Disabled by default.
4. Configure the maximum time
allowed for the peer to
reestablish a BGP session.
graceful-restart timer restart
timer
Optional.
150 seconds by default.
5. Configure the maximum time to
wait for the End-of-RIB marker.
graceful-restart timer
wait-for-rib timer
Optional.
180 seconds by default.
Configuring BGP NSR
The following matrix shows the feature and router compatibility:
Feature 6602 HSR6602 6604/6608/6616
Configuring BGP NSR No No
• Yes on routers with the RPE-X1 or
RSE-X1 MPU.
• No on routers with the MCP MPU.
BGP GR and nonstop routing (NSR) are used to ensure continuous routing upon a switchover from the
active MPU to the standby MPU. GR has been used earlier and is more mature. However, GR requires the
cooperation of neighboring devices to recover routing information. The new active MPU needs to learn
all routes after an active/standby switchover. This affects the convergence speed.
BGP NSR can overcome this problem. It backs up BGP neighbor and routing information from the active
MPU to the standby MPU when the device is starting or operating. After an active/standby switchover,
NSR can complete routing information recovery without requiring the cooperation of other devices.