H3C Technologies H3C SecPath F1000-E - Manual (Page 186)

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length of BS timeout, during which no BSR election takes place. If the BSR state times out and no
bootstrap message is received from the BSR, a new BSR election process is triggered among the C-BSRs.
Perform the following configuration on C-BSR routers.
Follow these steps to configure C-BSR timers:
To do… Use the command… Remarks
Enter system view system-view —
Enter IPv6 PIM view pim ipv6 —
Configure the BS period c-bsr interval interval
Optional
For the default value, see the note
below.
Configure the BS timeout c-bsr holdtime interval
Optional
For the default value, see the note
below.
NOTE:
About the BS period:
• By default, the BS period is determined by this formula: BS period = (BS timeout – 10) / 2. The default
BS timeout is 130 seconds, so the default BS period = (130 – 10) / 2 = 60 (seconds).
• If this parameter is manually configured, the system will use the configured value.
About the BS timeout:
• By default, the BS timeout value is determined by this formula: BS timeout = BS period × 2 + 10. The
default BS period is 60 seconds, so the default BS timeout = 60 × 2 + 10 = 130 (seconds).
• If this parameter is manually configured, the system will use the configured value.
CAUTION:
In configuration, make sure that the BS period is smaller than the BS timeout value.
Disabling BSM semantic fragmentation
Generally, a BSR periodically distributes the RP-set information in bootstrap messages within the IPv6
PIM-SM domain. It encapsulates a BSM in an IPv6 datagram and may split the datagram into fragments
if the message exceeds the maximum transmission unit (MTU). In respect of such IP fragmentation, loss of
a single IP fragment leads to unavailability of the entire message.
Semantic fragmentation of BSMs can solve this issue. When a BSM exceeds the MTU, it is split to multiple
bootstrap message fragments (BSMFs).
• Upon receiving a BSMF that contains the RP-set information of one group range, a non-BSR router
updates corresponding RP-set information directly.
• If the RP-set information of one group range is carried in multiple BSMFs, a non-BSR router updates
corresponding RP-set information upon receiving all these BSMFs.
Because the RP-set information contained in each segment is different, loss of some IP fragments will not
result in dropping of the entire message.
The function of BSM semantic fragmentation is enabled by default. Devices not supporting this function
may deem a fragment as an entire message, thus learning only part of the RP-set information. Therefore,