Specifications

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7-3
Cisco Nexus 3000 Series NX-OS Unicast Routing Configuration Guide, Release 5.0(3)U2(2)
OL-25782-02
Chapter 7 Configuring Bidirectional Forwarding Detection for BGP
Licensing Requirements for BFD
Security
Cisco NX-OS uses the packet Time to Live (TTL) value to verify that the BFD packets came from an
adjacent BFD peer. For all asynchronous and echo request packets, the BFD neighbor sets the TTL value
to 255 and the local BFD process verifies the TTL value as 255 before processing the incoming packet.
For the echo response packet, BFD sets the TTL value to 254.
Virtualization Support
BFD supports virtual routing and forwarding instances (VRFs). VRFs exist within virtual device
contexts (VDCs). By default, Cisco NX-OS places you in the default VDC and default VRF unless you
specifically configure another VDC and VRF.
Licensing Requirements for BFD
The following table shows the licensing requirements for this feature:
Prerequisites for BFD
BFD has the following prerequisites:
• You must enable the BFD feature (see the “Enabling the BFD Feature” section on page 7-6).
• For any client protocols that you want to enable BFD on, you enable BFD in that client protocol.
See the “Configuring BFD on BGP” section on page 7-13.
• Disable Internet Control Message Protocol (ICMP) redirect messages on a BFD-enabled interfaces.
• See other detailed prerequisites that are listed with the configuration tasks.
Guidelines and Limitations
BFD has the following configuration guidelines and limitations:
• BFD supports BFD version 1.
• BFD supports IPv4.
• BFD supports single-hop BFD.
• BFD for BGP supports single-hop eBGP peers and single-hop iBGP peers with update-source.
• BFD supports the following Layer 3 interfaces—physical interfaces, port channels, subinterfaces,
and VLAN interfaces (SVI).
• BFD for BGP does not support authentication for BFD or per-link BFD sessions on a port channel.
Product License Requirement
Cisco NX-OS BFD requires no license. Any feature not included in a license package is bundled with the Cisco NX-OS
system images and is provided at no extra charge to you. For a complete explanation of the Cisco NX-OS
licensing scheme, see the Cisco NX-OS Licensing Guide.