Cisco Nexus 9000 Series - Default Settings for Unicast RPF

• Beginning with Cisco NX-OS Release 9.2(1), for N9K-X9636C-R and N9K-X96136YC-R switches,
you can configure only one version of the available IPv4 and IPv6 Unicast RPF command on an interface.
However, this will enable Unicast RPF for both IPv4 and IPv6.
• For Cisco Nexus 9300-EX, FX, and FX2 Series switches, the ping to a directly connected peer IP interface
will fail when the peer IP interface has strict unicast RPF enabled with the ARP/ND to SRC IP is not
resolved.
• For Cisco Nexus 9300-EX, FX, and FX2 Series switches, packets from a host on the interface subnet
will drop due to the unicast RPF failure when the ARP/ND for the host IP is not resolved.
• The following guidelines and limitations apply only to Cisco Nexus 9500 Series switches with a
N9K-X9636C-R, N9K-X9636C-RX, or N9K-X9636Q-R line card:
• For strict uRPF to work, you must enable it on both the ingress interface and the interface where
the source IP address is learned.
• The switch hardware does not implement strict uRPF per the configured routing interface.
• Strict uRPF is implemented per learned route on strict uRPF-enabled interfaces.
• If a route is resolved as ECMP, strict uRPF will fall back to loose mode.
• Because of the hardware limitation on the trap resolution, uRPF might not be applied on
supervisor-bound packets via inband.
• For IP traffic, both IPv4 and IPv6 configurations should be enabled simultaneously.
• Due to hardware limitations, the N9K-X9636C-R, N9K-X9636C-RX, and N9K-X9636Q-R line
cards support only the following combinations:
Applied Traffic Check on Source IP AddressuRPF Configuration
Unipath MPLS
VPN for
N9K-X9636C-RX
Line Card
MPLS
Encap/VPN/ECMP
IP ECMPIP UnipathIPv6IPv4
AllowAllowAllowAllowDisableDisable
uRPF strictuRPF looseuRPF looseuRPF looseLooseLoose
uRPF strictuRPF looseuRPF looseuRPF strictStrictStrict
Default Settings for Unicast RPF
This table lists the default settings for unicast RPF parameters.
Table 38: Default Unicast RPF Parameter Settings
DefaultParameters
DisabledUnicast RPF
Cisco Nexus 9000 Series NX-OS Security Configuration Guide, Release 9.x
442
Configuring Unicast RPF
Default Settings for Unicast RPF