H3C Technologies H3C S12500-X Series Switches - Manual (Page 253)

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Configuring confederation compatibility
If any routers in the confederation do not comply with RFC 3065, enable confederation compatibility to
allow the router to work with those routers.
To configure confederation compatibility:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter BGP view. bgp as-number N/A
3. Enable confederation
compatibility.
confederation nonstandard
By default, confederation
compatibility is disabled.
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Configuring BGP GR
GR ensures forwarding continuous when a routing protocol restarts or an active/standby switchover
occurs. Two routers are required to complete a GR process. The following are router roles in a GR
process:
• GR restarter—Performs GR upon a BGP restart or active/standby switchover.
• GR helper—Helps the GR restarter to complete the GR process.
A device can act as a GR restarter and GR helper at the same time.
BGP GR works as follows:
1. The BGP GR restarter and helper exchange Open messages for GR capability negotiation. If both
parties have the GR capability, they establish a GR-capable session. The GR restarter sends the GR
timer set by the graceful-restart timer restart command to the GR helper in an Open message.
2. When an active/standby switchover occurs or BGP restarts, the GR restarter does not remove
existing BGP routes, and it still uses these routes for packet forwarding. The GR helper marks all
routes learned from the GR restarter as stale instead of deleting them, and it still uses these routes
for packet forwarding. During the GR process, packet forwarding is not interrupted.
3. After the active/standby switchover or BGP restart completes, the GR restarter reestablishes a BGP
session with the GR helper. If the BGP session fails to be established within the GR timer advertised
by the GR restarter, the GR helper removes the stale routes.
4. If the BGP session is established, routing information is exchanged for the GR restarter to retrieve
route entries and for the GR helper to recover stale routes. You can use the graceful-restart timer
wait-for-rib command to configure the time for the local router to wait for the End-Of-RIB (End of
Routing-Information-Base) marker, and control the route convergence speed. If routing information
exchange is not completed within the time, the GR restarter does not receive new routes. Instead,
the GR restarter updates its routing table and forwarding table with the BGP routes already
learned to complete BGP route convergence. The GR helper removes the stale routes.
Follow these guidelines when you configure BGP GR:
• The End-Of-RIB 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. It controls the time for the local end to receive updates from the peer.
Perform the following configuration on the GR restarter and GR helper.
To configure BGP GR: