Command Reference Guide

3Com Router 3000 Ethernet Family
Command Reference Guide Chapter 5 URPF Configuration Commands
3Com Corporation
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Chapter 5 URPF Configuration Commands
5.1 URPF Configuration Commands
5.1.1 ip urpf
Syntax
ip urpf { strict | loose } [ allow-default ] [ acl acl-number ]
undo ip urpf
View
Interface view
Parameter
strict: Strict check. The packet’s source address must be in the router’s FIB table. It
searches reversely for outgoing interfaces for the packet. At least one outgoing
address must match the packet’s incoming interface; otherwise URPF rejects the
packet.
loose: Loose check. The only requirement is that the packet’s source address is in the
router’s FIB table; otherwise URPF rejects the packet.
allow-default: Allows special treatment for the default route. When the default route
and the allow-default parameters are both configured, the principles of strict check
and loose check change.
acl-number: ACL number, ranges from 2000 to 3999.
Description
Use the ip urpf command to enable URPF check on the interface.
Use the undo ip urpf command to disable URPF check.
By default, URPF is disabled.
Example
# Enable strict URPF check on Ethernet2/2/0, allow special treatment for the default
route, and set ACL number to 2999.
[3Com-Ethernet2/2/0] ip urpf strict allow-default acl 2999