Disabling BSM semantic fragmentation

BSM semantic fragmentation enables a BSR to split a BSM into multiple BSM fragments (BSMFs) if the BSM exceeds the MTU. In this way, a non-BSR device can update the RP-set information for a group range after receiving all BSMFs for the group range. The loss of one BSMF only affects the RP-set information of the group ranges that the fragment contains.

If a device does not support BSM semantic fragmentation, it regards a BSMF as a BSM and updates the RP-set information each time it receives a BSMF. It learns only part of the RP-set information, which further affects the RP election. Therefore, if such a device exists in the IPv6 PIM-SM domain, you must disable BSM semantic fragmentation on all C-BSRs.

1. Enter system view.

   system-view

2. Enter IPv6 PIM view.

   ipv6 pim [ vpn-instance vpn-instance-name ]

3. Disable BSM semantic fragmentation.

   undo bsm-fragment enable

   By default, BSM semantic fragmentation is enabled.