395
Ste
Command
Remarks
3. Configure the BS period.
c-bsr interval interval
Optional.
By default, the BS period is
determined by the formula "BS
period = (BS timeout – 10) / 2."
The default BS timeout is 130
seconds, so the default BS period =
(130 – 10) / 2 = 60 (seconds).
The BS period value must be
smaller than the BS timeout value
4. Configure the BS timeout
timer.
c-bsr holdtime interval
Optional.
By default, the BS timeout value is
determined by the formula "BS
timeout timer = BS period × 2 +
10." The default BS period is 60
seconds, so the default BS timeout
timer = 60 × 2 + 10 = 130
(seconds).
NOTE:
If yon configure the BS period or the BS timeout timer, the system uses the confi
ured one instead of the
default one.
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 might 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).
• After 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 after 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.
Generally, a BSR performs BSM semantic fragmentation according to the MTU of its BSR interface.
However, the semantic fragmentation of BSMs originated because of learning of a new IPv6 PIM
neighbor is performed according to the MTU of the outgoing interface.
The function of BSM semantic fragmentation is enabled by default. Devices not supporting this function
might deem a fragment as an entire message and learn only part of the RP-set information. Therefore, if
such devices exist in the IPv6 PIM-SM domain, you need to disable the semantic fragmentation function
on the C-BSRs.
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