Bgp-Rib Feedback Mechanism For Update Generation; Configuration Examples For Rib Monitoring; Output Of Show Route Command: Example - Cisco ASR 9000 Series Routing Configuration Manual

BGP-RIB Feedback Mechanism for Update Generation

Command or Action
Example:
RP/0/RSP0/CPU0:router#show rcc ipv6 unicast statistics
scan-id 120
Or
RP/0/RSP0/CPU0:router#show lcc ipv6 unicast statistics
scan-id 120
BGP-RIB Feedback Mechanism for Update Generation
The Border Gateway Protocol-Routing Information Base (BGP-RIB) feedback mechanism for update generation
feature avoids premature route advertisements and subsequent packet loss in a network. This mechanism
ensures that routes are installed locally, before they are advertised to a neighbor.
BGP waits for feedback from RIB indicating that the routes that BGP installed in RIB are installed in forwarding
information base (FIB) before BGP sends out updates to the neighbors. RIB uses the the BCDL feedback
mechanism to determine which version of the routes have been consumed by FIB, and updates the BGP with
that version. BGP will send out updates of only those routes that have versions up to the version that FIB has
installed. This selective update ensures that BGP does not send out premature updates resulting in attracting
traffic even before the data plane is programmed after router reload, LC OIR, or flap of a link where an
alternate path is made available.
To configure BGP to wait for feedback from RIB indicating that the routes that BGP installed in RIB are
installed in FIB, before BGP sends out updates to neighbors, use the update wait-install command in router
address-family IPv4 or router address-family VPNv4 configuration mode. The show bgp, show bgp neighbors,
and show bgp process performance-statistics commands display the information from update wait-install
configuration.

Configuration Examples for RIB Monitoring

RIB is not configured separately for the Cisco IOS XR system. RIB computes connectivity of the router with
other nodes in the network based on input from the routing protocols. RIB may be used to monitor and
troubleshoot the connections between RIB and its clients, but it is essentially used to monitor routing
connectivity between the nodes in a network. This section contains displays from the show commands used
to monitor that activity.

Output of show route Command: Example

The following is sample output from the show route command when entered without an address:
show route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
Cisco ASR 9000 Series Aggregation Services Router Routing Configuration Guide, Release 5.3.x
512
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
Implementing and Monitoring RIB
Purpose