- Cisco BGP Overview
- BGP 4
- Configuring a Basic BGP Network
- BGP 4 Soft Configuration
- BGP Support for 4-byte ASN
- IPv6 Routing: Multiprotocol BGP Extensions for IPv6
- IPv6 Routing: Multiprotocol BGP Link-Local Address Peering
- IPv6 Multicast Address Family Support for Multiprotocol BGP
- Configuring Multiprotocol BGP (MP-BGP) Support for CLNS
- Connecting to a Service Provider Using External BGP
- BGP Route-Map Continue
- BGP Route-Map Continue Support for Outbound Policy
- Removing Private AS Numbers from the AS Path in BGP
- Configuring BGP Neighbor Session Options
- BGP Neighbor Policy
- BGP Dynamic Neighbors
- BGP Support for Next-Hop Address Tracking
- BGP Restart Neighbor Session After Max-Prefix Limit Reached
- BGP Support for Dual AS Configuration for Network AS Migrations
- Configuring Internal BGP Features
- BGP VPLS Auto Discovery Support on Route Reflector
- BGP FlowSpec Route-reflector Support
- BGP Flow Specification Client
- BGP NSF Awareness
- BGP Graceful Restart per Neighbor
- BGP Support for BFD
- IPv6 NSF and Graceful Restart for MP-BGP IPv6 Address Family
- BGP Link Bandwidth
- iBGP Multipath Load Sharing
- BGP Multipath Load Sharing for Both eBGP and iBGP in an MPLS-VPN
- Loadsharing IP Packets over More Than Six Parallel Paths
- BGP Policy Accounting
- BGP Policy Accounting Output Interface Accounting
- BGP Cost Community
- BGP Support for IP Prefix Import from Global Table into a VRF Table
- BGP Support for IP Prefix Export from a VRF Table into the Global Table
- BGP per Neighbor SoO Configuration
- Per-VRF Assignment of BGP Router ID
- BGP Next Hop Unchanged
- BGP Support for the L2VPN Address Family
- BGP Event-Based VPN Import
- BGP Best External
- BGP PIC Edge for IP and MPLS-VPN
- Detecting and Mitigating a BGP Slow Peer
- Configuring BGP: RT Constrained Route Distribution
- Configuring a BGP Route Server
- BGP Diverse Path Using a Diverse-Path Route Reflector
- BGP Enhanced Route Refresh
- Configuring BGP Consistency Checker
- BGP—Origin AS Validation
- BGP MIB Support
- BGP 4 MIB Support for Per-Peer Received Routes
- BGP Support for Nonstop Routing (NSR) with Stateful Switchover (SSO)
- BGP NSR Auto Sense
- BGP NSR Support for iBGP Peers
- BGP Graceful Shutdown
- BGP — mVPN BGP sAFI 129 - IPv4
- BGP-MVPN SAFI 129 IPv6
- BFD—BGP Multihop Client Support, cBit (IPv4 and IPv6), and Strict Mode
- BGP Attribute Filter and Enhanced Attribute Error Handling
- BGP Additional Paths
- BGP-Multiple Cluster IDs
- BGP-VPN Distinguisher Attribute
- BGP-RT and VPN Distinguisher Attribute Rewrite Wildcard
- VPLS BGP Signaling
- Multicast VPN BGP Dampening
- BGP—IPv6 NSR
- BGP-VRF-Aware Conditional Advertisement
- BGP—Selective Route Download
- BGP—Support for iBGP Local-AS
- eiBGP Multipath for Non-VRF Interfaces (IPv4/IPv6)
- L3VPN iBGP PE-CE
- BGP NSR Support for MPLS VPNv4 and VPNv6 Inter-AS Option B
- BGP-RTC for Legacy PE
- BGP PBB EVPN Route Reflector Support
- BGP Monitoring Protocol
- VRF Aware BGP Translate-Update
- BGP Support for MTR
- BGP Accumulated IGP
- BGP MVPN Source-AS Extended Community Filtering
- BGP AS-Override Split-Horizon
- BGP Support for Multiple Sourced Paths Per Redistributed Route
Contents
- BGP NSR Auto Sense
- Finding Feature Information
- Information About BGP NSR Auto Sense
- Benefits of BGP NSR Auto Sense
- Consequence of Reverting to NSR Without Auto Sense
- How to Disable the BGP NSR Auto Sense Feature
- Disabling the BGP NSR Auto Sense Feature
- Configuration Example for BGP NSR Auto Sense
- Example: Disabling the BGP NSR Auto Sense Feature
- Additional References
- Feature Information for BGP NSR Auto Sense
BGP NSR Auto Sense
The BGP NSR Auto Sense feature is the default behavior implemented to reduce unnecessary churn in the event of a Route Processor (RP) failover. Prior to this feature, when an Active RP went down, the new Active RP that was taking over to provide Border Gateway Protocol (BGP) nonstop routing (NSR) would send a route-refresh request to all peers configured with NSR. However, the new Active RP had already received all the incoming updates while acting as the Standby RP. Sending route-refresh requests caused unnecessary BGP churn during switchover; this feature prevents such route-refresh requests by default. This feature also provides NSR support to peers that lack route-refresh capability. If you want to revert to the old behavior of sending route-refresh requests, a new command is available to make that happen.
- Finding Feature Information
- Information About BGP NSR Auto Sense
- How to Disable the BGP NSR Auto Sense Feature
- Configuration Example for BGP NSR Auto Sense
- Additional References
- Feature Information for BGP NSR Auto Sense
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Information About BGP NSR Auto Sense
Benefits of BGP NSR Auto Sense
The BGP NSR Auto Sense feature has the following benefits:
This feature is a default behavior that reduces unnecessary churn in the event of a Route Processor (RP) failover. Prior to this feature, when an Active RP went down, the new Active RP that was taking over to provide BGP nonstop routing (NSR) would send a route-refresh request to all peers configured with NSR. However, the Active RP had already received all the incoming updates while acting as the Standby RP. Sending route-refresh requests caused unnecessary BGP churn during switchover; this feature prevents such route-refresh requests by default.
This feature also provides NSR support to peers that lack route-refresh capability. Prior to this feature, NSR was not supported for peers that lack route-refresh capability.
There is no need to configure this feature; it is the default behavior in releases where this feature is implemented.
If you want to revert to the former behavior of a new Active RP sending route-refresh requests when an RP goes down, you can use the bgp sso route-refresh-enable command.
Consequence of Reverting to NSR Without Auto Sense
You might have a reason not to want the default behavior of the BGP NSR Auto Sense feature. If you want to revert to the former behavior of a new Active RP sending route-refresh requests when an RP goes down, you can use the bgp sso route-refresh-enable command. This action causes peers that did not exchange route-refresh capability in the received OPEN message to have NSR support disabled.
How to Disable the BGP NSR Auto Sense Feature
Disabling the BGP NSR Auto Sense Feature
The BGP NSR Auto Sense feature is enabled by default. Perform this task only if you want to disable the feature, for example, if routes that were being advertised at the point of switchover did not get processed by the Standby RP (new Active RP) for some reason. In that case, sending a route-refresh to request all the routes that the peer had ever advertised would be helpful. After performing this task, in the event of a failover, a new Active RP will send route-refresh requests to peers configured with NSR.
1.
enable
2.
configure
terminal
3.
router
bgp
as-number
4.
bgp
sso
route-refresh-enable
5.
end
6.
show ip bgp vpnv4 all neighbor [ip-address]
7.
show ip bgp vpnv4 all sso summary
DETAILED STEPS
Configuration Example for BGP NSR Auto Sense
Example: Disabling the BGP NSR Auto Sense Feature
router bgp 65600
bgp sso route-refresh-enable
Additional References
Related Documents
Related Topic |
Document Title |
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Cisco IOS commands |
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BGP commands |
Technical Assistance
Description |
Link |
|---|---|
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The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. |
Feature Information for BGP NSR Auto Sense
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Feature Name |
Releases |
Feature Information |
|---|---|---|
|
BGP NSR Auto Sense |
15.2(2)S Cisco IOS XE Release 3.6S |
The BGP NSR Auto Sense feature is implemented by default to reduce unnecessary churn in the event of an RP failover. This feature also provides NSR support to peers that lack route-refresh support. The following command was introduced: bgp sso route-refresh-enable. |