Cisco NCS 5500 Series

CHAPTER 7
Implementing BFD
Bidirectional forwarding detection (BFD) provides low-overhead, short-duration detection of failures in the
path between adjacent forwarding engines. BFD allows a single mechanism to be used for failure detection
over any media and at any protocol layer, with a wide range of detection times and overhead. The fast detection
of failures provides immediate reaction to failure in the event of a failed link or neighbor.
• BFD Overview , on page 205
• BFD over Bundle, on page 213
• BFD Transparency, on page 217
• Bidirectional Forwarding Detection over Logical Bundle , on page 222
• IPv4 Multihop BFD, on page 227
BFD Overview
Bidirectional forwarding detection (BFD) provides low-overhead, short-duration detection of failures in the
path between adjacent forwarding engines. BFD allows a single mechanism to be used for failure detection
over any media and at any protocol layer, with a wide range of detection times and overhead. The fast detection
of failures provides immediate reaction to failure in the event of a failed link or neighbor.
Restrictions
These restrictions apply to BFD:
• Demand mode is not supported in Cisco IOS XR software.
• BFD echo mode and encryption are not supported.
• BFD hardware offload for IPv4 is supported.
• Only the static, OSPF, BGP and IS-IS applications are supported on BFD.
• BFD dampening is supported starting from Cisco IOS XR Release 6.3.2.
• BFD multihop is supported starting from IOS XR Release 6.3.2 but BFD multihop over non IP core is
not supported.
• Only static routes are supported in IPv6 BFD.
• BFD is only supported in IP core. It cannot coexist with Label distribution Protocol, or Segment Routing,
or Traffic Engineering in the core.
Routing Configuration Guide for Cisco NCS 5500 Series Routers, IOS XR Release 6.3.x
205