3Com Switch 8800 Advanced Software V5 Configuration Guide

Configuring PIM-SM 579
Enabling PIM-SM With PIM-SM enabled, a device sends hello messages periodically to discover PIM
neighbors and processes messages from PIM neighbors. When deploying a
PIM-SM domain, you are recommended to enable PIM-SM on all interfaces of
non-border devices (border devices are PIM-enabled routers or PIM-enabled
switches located on the boundary of BSR admin-scope regions).
Follow these steps to enable PIM-SM:
c
CAUTION:
■ All the interfaces of the same device must work in the same PIM mode.
■ After PIM-SM is enabled on a VLAN interface, IGMP snooping cannot be
enabled in the VLAN corresponding to the VLAN interface, and vice versa.
Configuring a BSR
n
The BSR is dynamically elected from a number of C-BSRs. Because it is
unpredictable which device 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,
global scope level, and BSR admin-scope level.
■ By default, the global scope parameters and BSR admin-scope parameters are
those configured at the global configuration level.
■ Parameters configured at the global scope level or BSR admin-scope level have
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
device can be configured as 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 devices in the backbone network. When
configuring a router as a C-BSR, be sure to specify a PIM-SM-enabled interface.
The BSR election process is as follows:
■ 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.
■ 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 the
To do... Use the command... Remarks
Enter system view system-view -
Enable IP multicast routing multicast routing-enable Required
Disable by default
Enter VLAN/POS interface
view
interface interface-type
interface-number
-
Enable PIM-SM pim sm Required
Disabled by default