PLANET XGS3-24040 - Manual (Page 187)

Chapter 21 Layer 3 Forward Configuration
21-17
21.4.1.1 IP URPF Operating Mechanism
At present the UPRF relies on the ACL function provided by the switch chips.
Firstly, globally enable the URPF function to monitor the changes in the router table: create a corresponding
URPF permit ACL rule for each router in the router table FIB. In URPF strict mode, the format of ACL rules is:
the source address segments of inbound packets + the ingress interface VID of inbound packets. The source
address segments of inbound packets are in correspondence with the destination address segments in the
FIB router table entries, while the ingress interface VID of inbound packets with the egress interface VID in the
FIB router table entries. In URPF loose mode, the format of ACL rules is the source address segments of
inbound packets, which are in correspondence with destination address segments in the FIB router table
entries.
After enabling URPF on the port: bind the port to RUPF rules, and create the default hardware for DENY ALL
rule distribution.
The above operations will guarantee that, when data reach the port, only those match the rules can pass
through it with all others dumped.
The present corresponding ACL rule privilege is low, not blocking all kinds of protocol packets; hence,
enabling this function will not affect the normal operation of routing protocols of the switch.
21.4.2 URPF Configuration Task Sequence
1. Enable URPF
2. Enable URPF on port
3. Display and debug URPF relevant information
1. Globally enable URPF
Command Explanation
Global mode
urpf enable
no urpf enable
Globally enable and disable URPF.
2. Enable URPF on port
Command Explanation
Port mode
ip urpf enable {loose | strict}
{allow-default-route }
no ip urpf enable
Enable and disable URPF on port.