HP 6125XLG Ip Multicast Configuration Manual page 119

A PIM domain border is a bootstrap message boundary. Each BSR has its specific service scope. A
number of PIM domain border interfaces partition a network into different BIDIR-PIM domains. Bootstrap
messages cannot cross a domain border in either direction.
Perform the following configuration on routers that you want to configure as a PIM domain border.
To configure a PIM domain border:
Step
1. Enter system view.
2. Enter interface view.
3. Configure a PIM domain
border.
Disabling the BSM semantic fragmentation function
A BSR periodically advertises the RP-set information in BSMs within the BIDIR-PIM domain. It encapsulates
a BSM in an IP datagram. When a BSM exceeds the MTU, it is split into multiple BSM fragments (BSMFs).
The loss of a single IP fragment leads to unavailability of the entire message.
Semantic fragmentation of BSMs can solve this issue. When a non-BSR router receives a BSMF, it
examines the RP-set information for a multicast group range:
If the RP-set information is carried in one BSMF, the router directly updates the RP-set information for
•
the group range.
If the RP-set information is carried in multiple BSMFs, the router updates the RP-set information for the
•
group range after receiving all these BSMFs. The loss of some IP fragments does not result in
dropping of the entire BSM.
The BSM semantic fragmentation function is enabled by default. A device that does not support this
function might regard a fragment as a BSM. Therefore, the device learns only part of the RP-set
information. If such devices exist in the BIDIR-PIM domain, you must disable the BSM semantic
fragmentation function on the C-BSRs.
To disable the BSM semantic fragmentation function:
Step
1. Enter system view.
2. Enter PIM view.
3. Disable the BSM semantic
fragmentation function.
NOTE:
Generally, a BSR performs BSM semantic fragmentation according to the MTU of its BSR interface. For
BSMs originated due to learning of a new PIM neighbor, semantic fragmentation is performed according
to the MTU of the interface that sends the BSMs.
Command
system-view
interface interface-type
interface-number
pim bsr-boundary
Command
system-view
pim [ vpn-instance
vpn-instance-name ]
undo bsm-fragment enable
109
Remarks
N/A
N/A
By default, no PIM domain border
is configured.
Remarks
N/A
N/A
By default, BSM semantic
fragmentation is enabled.