User Manual
UMN:CLI
V8102
533
10.3.3.2
Bootstrap Router
The bootstrap router (BSR) mechanism is one way that a multicast router can learn the
set of group-to-RP mappings required in order to function.
All multicast routers in PIM-SM domain can be potentially the bootstrap router (BSR);
they are all considered as candidate BSRs. To elect the BSR among the candidate BSRs,
each candidate BSR floods the bootstrap messages with its information to the domain.
When receiving the bootstrap messages, the candidate BSRs examine the messages,
and then the one with the highest priority is elected as the BSR. If more than one candi-
date with the same highest priority, the one with the higher IP address is elected.
The elected BSR is responsible to periodically send out bootstrap messages including the
RP-set, allowing all the routers in the PIM-SM domain determine which router is the RP
that covers given multicast groups.
Interface for Candidate BSR
To configure an interface to flood the candidate BSR advertisement, use the following
command.
Command
Mode
Description
ip pim bsr-candidate
INTERFACE
Global
Configures an interface to flood the candidate BSR
advertisement.
INTERFACE: interface name
0-32: hash mask length for RP selection
0-255: priority for candidate BSR
ip pim bsr-candidate
INTERFACE
<0-32>
ip pim bsr-candidate
INTERFACE
<0-32> <0-255>
no ip pim bsr-candidate
Configures an interface not to flood the candidate BSR
advertisement.
Preventing BSR Messages
Following commands configure an interface bordering another PIM domain to avoid the
exchange of BSR messages between the two domains. BSR messages should not be
exchanged between different domains, because routers in one domain may elect rendez-
vous points (RPs) in the other domain, resulting in a protocol malfunction or loss of isola-
tion between the domains. To prevent bootstrap router messages from being sent or re-
ceived through an interface, use the following command.
Command
Mode
Description
ip pim bsr-border
Intreface
[loopback
/VLAN]
Configures an interface bordering another PIM domain
to avoid the exchange of BSR messages.
no ip pim bsr-border
Clearing RP-Set
The BSR periodically distributes the bootstrap message that includes a set of the infor-
mation received from each candidate RP (RP-set) to all the routers in the PIM-SM domain.
You can also clear all RP-set to reset.
