3com 5500-ei pwr Instrução De Instalação

 

12 

Configure candidate 
RPs 

c-rp interface-type 
interface-number 
[ group-policy acl-number | 
priority priority ]* 

Optional 

By default, candidate RPs are not set for 
the switch and the value of priority is 0. 

Limit the range of 
valid C-RPs 

crp-policy acl-number 

Optional 

By default, the range of valid C-RPs is 
not set for the switch. 

 

z 

If the range of multicast groups that an RP serves is not specified when the RP is configured, the 

RP serves all multicast groups.  

z 

If the configured static RP address is the address of an UP interface on the local switch, the switch 

will serve as an RP.  

z 

Static RPs do not take effect when the RP generated by the BSR mechanism takes effect.  

 

A PIM-SM domain can have only one BSR, but must have at least one C-BSR. Any router can be 

configured as a C-BSR. Elected from C-BSRs, the BSR is responsible for collecting and advertising RP 

information in the PIM-SM domain. 

C-BSRs should be configured on routers in the backbone network. When configuring a router as a 

C-BSR, be sure to specify a PIM-SM-enabled interface on the router. The BSR election process is 

summarized as follows: 

z 

Initially, every C-BSR assumes itself to be the BSR of this PIM-SM domain, and uses its interface 

IP address as the BSR address to send bootstrap messages.  

z 

When a C-BSR receives the bootstrap message of another C-BSR, it first compares its own priority 

with the other C-BSR’s priority carried in message. The C-BSR with a higher priority wins. If there is 

a tie in the priority, the C-BSR with a higher IP address wins. The loser uses the winner’s BSR 

address to replace its own BSR address and no longer assumes itself to be the BSR, while the 

winner retains its own BSR address and continues assuming itself to be the BSR.  

Configuring a legal range of BSR addresses enables filtering of bootstrap messages based on the 

address range, thus to prevent a maliciously configured host from masquerading as a BSR. The same 

configuration needs to be made on all routers in the PIM-SM domain. The following are typical BSR 

spoofing cases and the corresponding preventive measures: 

1)  Some maliciously configured hosts can forge bootstrap messages to fool routers and change RP 

mappings. Such attacks often occur on border routers. Because a BSR is inside the network 

whereas hosts are outside the network, you can protect a BSR against attacks from external hosts 

by enabling the border routers to perform neighbor checks and RPF checks on bootstrap 

messages and discard unwanted messages.  

2)  When a router in the network is controlled by an attacker or when an illegal router is present in the 

network, the attacker can configure this router as a C-BSR and make it win BSR election to control