The BFD Support for EIGRP IPv6 feature provides Bidirectional Forwarding Detection (BFD) support for Enhanced Interior Gateway Routing Protocol (EIGRP) IPv6 sessions, thereby facilitating rapid fault detection and alternate-path selection in EIGRP IPv6 topologies. BFD is a detection protocol that provides a consistent failure-detection method for network administrators, and network administrators use BFD to detect forwarding path failures at a uniform rate and not at variable rates for different routing protocol 'Hello' mechanisms. This failure-detection methodology ensures easy network profiling and planning and consistent and predictable reconvergence time. This document provides information about BFD support for EIGRP IPv6 networks and explains how to configure BFD support in EIGRP IPv6 networks.
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Prerequisites for BFD Support for EIGRP IPv6
EIGRP IPv6 sessions have a shutdown option in router, address family, and address-family interface configuration modes. To enable BFD support on EIGRP IPv6 sessions, the routing process should be in no shut mode in the abovementioned modes.
Restrictions for BFD Support for EIGRP IPv6
The BFD Support for EIGRP IPv6 feature is supported only in EIGRP named mode.
EIGRP supports only single-hop Bidirectional Forwarding Detection (BFD).
The BFD Support for EIGRP IPv6 feature is not supported on passive interfaces.
Bidirectional Forwarding Detection (BFD) is a detection protocol that provides fast-forwarding, path-failure detection for all media types, encapsulations, topologies, and routing protocols. The BFD Support for EIGRP IPv6 feature enables BFD to interact with the Enhanced Interior Gateway Routing Protocol (EIGRP) to create BFDv6 sessions between EIGRP neighbors. In a BFD-enabled EIGRP IPv6 session, BFD constantly monitors the forwarding path (from a local device to a neighboring device) and provides consistent failure detection at a uniform rate. Because failure detection happens at a uniform rate and not at variable rates, network profiling and planning is easier, and the reconvergence time remains consistent and predictable.
BFD is implemented in EIGRP at multiple levels; it can be implemented per interface or on all interfaces. When BFD is enabled on a specific interface, all peer relationships formed through the EIGRP "Hello" mechanism on that interface are registered with the BFD process. Subsequently, BFD establishes a session with each of the peers in the EIGRP topology and notifies EIGRP through a callback mechanism of any change in the state of any peer. When a peer is lost, BFD sends a "peer down" notification to EIGRP, and EIGRP unregisters a peer from BFD. BFD does not send a "peer up" notification to EIGRP when the peer is up because BFD now has no knowledge of the state of the peer. This behavior prevents rapid neighbor bouncing and repetitive route computations. The EIGRP "Hello" mechanism will later allow peer rediscovery and reregistration with the BFD process.
Sets the device ID used by EIGRP when EIGRP peers communicate with their neighbors.
Step 11
af-interface default
Example:
Device(config-router-af)# af-interface default
Configures interface-specific commands on all interfaces that belong to an address family in EIGRP named mode configurations, and enters address-family interface configuration mode.
Step 12
bfd
Example:
Device(config-router-af-interface)# bfd
Enables BFD on all interfaces.
Step 13
end
Example:
Device(config-router-af-interface)# end
Exits address-family interface configuration mode and returns to privileged EXEC mode.
Step 14
showeigrpaddress-familyipv6neighbors
Example:
Device# show eigrp address-family ipv6 neighbors
(Optional) Displays neighbors for which BFD has been enabled.
Configures interface-specific commands on an interface that belongs to an address family in an EIGRP named mode configuration, and enters address-family interface configuration mode.
Step 12
bfd
Example:
Device(config-router-af-interface)# bfd
Enables BFD on all interfaces.
Step 13
end
Example:
Device(config-router-af-interface)# end
Exits address-family interface configuration mode and returns to privileged EXEC mode.
Step 14
showeigrpaddress-familyipv6neighbors
Example:
Device# show eigrp address-family ipv6 neighbors
(Optional) Displays neighbors for which BFD has been enabled.
Configuration Examples for BFD Support for EIGRP IPv6
"Configuring EIGRP" chapter in
IP Routing: EIGRP Configuration Guide
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Feature Information for BFD Support for EIGRP IPv6
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.
Table 1
Feature Information for BFD Support for EIGRP IPv6
Feature Name
Releases
Feature Information
BFD Support for EIGRP IPv6
15.2(2)S
15.2(4)M
Bidirectional Forwarding Detection (BFD) is a detection protocol that provides fast-forwarding, path-failure detection for all media types, encapsulations, topologies, and routing protocols. BFD helps network administrators to ensure easier network profiling and planning and consistent and predictable reconvergence time. BFD interacts with Enhanced Interior Gateway Routing Protocol (EIGRP) to create sessions (IPv4 type sessions) between EIGRP neighbors for fast-forwarding, path-failure detections. Each session tests the forwarding path for a single route from a local router to a neighboring router. For any change in state (forwarding path goes down or forwarding path comes up) for any of the sessions, BFD notifies EIGRP of the new state for that route. Support has been added for EIGRP IPv6 neighbors to use BFD as a fall-over mechanism.
The following commands were introduced or modified:
bfd,
show eigrp address-family
neighbors,
show eigrp
address-family interfaces.
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