HP 6125G HP 6125G & 6125G/XG Blade Switches IP Multicast Configuration - Page 134

Disabling BSM semantic fragmentation, If you con the BS period or the BS timeout timer

Page 134 highlights

Step Command 3. Configure the BS period. c-bsr interval interval 4. Configure the BS timeout timer. c-bsr holdtime interval Remarks Optional. By default, the BS period is determined by the formula "BS period = (BS timeout timer- 10) / 2." The default BS timeout timer is 130 seconds, so the default BS period is (130 - 10) / 2 = 60 (seconds). The BS period value must be smaller than the BS timeout timer. Optional. By default, the BS timeout timer 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 you configure the BS period or the BS timeout timer, the system uses the configured one instead of the default one. Disabling BSM semantic fragmentation Generally, a BSR periodically distributes the RP-set information in bootstrap messages within the PIM-SM domain. It encapsulates a BSM in an IP 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 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 PIM-SM domain, you need to disable the semantic fragmentation function on the C-BSRs. To disable the BSM semantic fragmentation function: 123

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123
Step
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 timer– 10) /
2." The default BS timeout timer is
130 seconds, so the default BS
period is (130 – 10) / 2 = 60
(seconds).
The BS period value must be
smaller than the BS timeout timer.
4.
Configure the BS timeout
timer.
c-bsr holdtime
interval
Optional.
By default, the BS timeout timer 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 you configure the BS period or the BS timeout timer, the system uses the configured one instead of the
default one.
Disabling BSM semantic fragmentation
Generally, a BSR periodically distributes the RP-set information in bootstrap messages within the PIM-SM
domain. It encapsulates a BSM in an IP 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 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 PIM-SM domain, you need to disable the semantic fragmentation function on the
C-BSRs.
To disable the BSM semantic fragmentation function: