Configuring A Bsr - 3Com MSR 50 Series Configuration Manual

1178 C 71: PIM C
HAPTER ONFIGURATION
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Configuring a BSR

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To do...
Enable IP multicast routing
Enter interface view
Enable PIM-SM
CAUTION: All the interfaces in the same VPN instance on the same router must
work in the same PIM mode.
The BSR is dynamically elected from a number of C-BSRs. Because it is
unpredictable which router will finally win a BSR election, the commands
introduced in this section must be configured on all C-BSRs.
About the Hash mask length and C-BSR priority for RP selection calculation
You can configure these parameters at three levels: global configuration level,
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global scope level, and BSR admin-scope level.
By default, the global scope parameters and BSR admin-scope parameters are
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those configured at the global configuration level.
Parameters configured at the global scope level or BSR admin-scope level have
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higher priority than those configured at the global configuration level.
Performing basic C-BSR configuration
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, a BSR is responsible for
collecting and advertising RP information in the PIM-SM.
C-BSRs should be configured on routers in the backbone network. When
configuring a router as a C-BSR, be sure that this router is PIM-SM enabled. The
BSR election process is as follows:
Initially, every C-BSR assumes itself to be the BSR of this PIM-SM domain, and
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uses its interface IP address as the BSR address to send bootstrap messages.
When a C-BSR receives the bootstrap message of another C-BSR, it first
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compares its own priority with the other C-BSR's priority carried in the
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 keeps its own BSR address and continues assuming itself
to be the BSR.
Configuring a legal range of BSR addresses enables filtering of BSR messages
based on the address range, thus to prevent malicious hosts from initiating attacks
by disguising themselves as legitimate BSRs. To protect legitimate BSRs from being
Use the command...
multicast routing-enable
interface interface-type
interface-number
pim sm
Description
Required
Disabled by default
-
Required
Disabled by default