HP A8800 Configuration Manual page 410

IMPORTANT:
Be sure to configure a BS period smaller than the BS timeout value.
If you configure the BS period or the BS timeout timer, the system uses the configured one instead of the
default one.
Perform the following configuration on C-BSR routers.
To configure C-BSR timers:
Step
1. Enter system view.
2. Enter IPv6 PIM view.
3. Configure the BS period.
4. Configure the BS timeout.
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 does 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,
if such devices exist in the IPv6 PIM-SM domain, you need to disable the semantic fragmentation function
on the C-BSRs.
To disable the BSM semantic fragmentation function:
Step
1. Enter system view.
Command
system-view
pim ipv6
c-bsr interval interval
c-bsr holdtime interval
Command
system-view
398
Remarks
N/A
N/A
Optional.
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).
Optional.
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).
Remarks
N/A