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DES-7200 Configuration Guide Chapter 6 URPF Configuration
6-5
(including the sampling time point reaching the drop rate)", the drop rate is calculated by
dividing the currently calculated number of dropped packets by the time of URPF running. The
subsequent method for drop rate computation: Calculated the number of currently dropped
packets at every drop rate computation interval, deduct the number of dropped packets before
the drop rate sampling interval, and then divide the difference by drop rate sampling interval to
obtain the current drop rate.
z Interface-based and global-based drop rate computation and monitoring is allowed.
For configurations related to URPF monitoring, please refer to “
Configure URPF drop rate
notification”.
6.1.3 Operating principle
The operating principle of URPF has been described in the section of "Characteristics of
URPF".
URPF functions can be applied to IPv4/IPv6 messages according to configurations. However,
please note that the following messages will not be subject to URPF check.
URPF check is only applied to the source address with destination address being IPv4/IPv6
message, and those with destination address being multicast message will be skipped.
For DHCP/BOOTP messages with source IP address being 0.0.0.0 and destination IP address
being 255.255.255.255, the URPF check will be skipped.
For IPv6 messages with source IP address being Link local address, the URPF check will be
skipped.
6.1.4 Application
restrictions
DES-7200 products which support URPF include:
Router products.
B-class line cards of DES-7200 series products and DES-7200-MPLS line cards.
The URPF function supported by our router products has the following application restrictions:
Router products only support URPF function during progress forwarding. If the fast forwarding
is enabled on the interface (interface configuration mode: ip ref), the URPF function will be
enabled.
URPF function also has the following characteristics in switch and router products:
After URPF is enabled, a route pointing source address to NULL interface will still be subject to
URPF check instead of discarding.