Command Reference Guide

3Com Router 3000 Ethernet Family
Command Reference Guide Chapter 3 PIM Configuration Commands
3Com Corporation
3-4
Example
# Configure the interface Ethernet1/0/0 as the candidate RP for all groups.
<3Com> system-view
[3Com] multicast routing-enable
[3Com] pim
[3Com-pim] c-rp ethernet 1/0/0
3.1.4 crp-policy
Syntax
crp-policy acl-number
undo crp-policy
View
PIM view
Parameter
acl-number: ACL number used by C-RP filter policy, ranging from 3000 to 3999.
Description
Use the crp-policy command to restrict the range for valid C-RP and the group range
served by each C-RP, preventing C-RP cheating.
Use the undo crp-policy command to restore the normal state without any range
restriction and regard all the messages received are valid.
In PIM SM network which uses BSR mechanism, any router can set itself as a C-RP
serving the specific group range. If it is elected in RP election, it will become an RP
serving in the group range.
In BSR mechanism C-RP router unicasts C-RP information to BSR router which is
responsible for advertising all C-RP information to the whole network by using BRP
information.
To prevent C-RP cheating, crp-policy is needed to configure on BSR router to restrict
the range for valid C-RP and the group address range it serves. Each C-BSR may
become a BSR possibly, so the same filter policy should be configured on each C-BSR.
This command uses the ACL numbered from 3000 to 3999. The parameter source in
the related rule command indicates C-RP address and destination indicates the group
range the C-RP serves. Upon matching the received C-RP message, only when the
C-RP address in the packet matches source address and the group address range in
the packet is the subset of that in ACL, can this configuration be regarded successful.
Related command: acl and rule.