HP A6600 Configuration Manual page 340

Configuring C-BSR timers
The BSR election winner multicasts its own IPv6 address and RP-Set information through bootstrap
messages within the entire zone it serves. The BSR floods bootstrap messages throughout the network at
the interval of BS (BSR state) period. Any C-BSR that receives a bootstrap message retains the RP-set for
the 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.
To do...
1. Enter system view.
2. Enter IPv6 PIM view.
3. Configure the BS period.
4. Configure the BS timeout.
BS period and timeout settings
Make sure that the BS period value is smaller than the BS timeout value.
The BS period defaults to the value 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 timeout setting defaults to the value determined by the formula:
BS timeout = BS period × 2 + 10
The default BS period is 60 seconds, so the default BS timeout = 60 × 2 + 10 = 130 (seconds)
Disabling BSM semantic fragmentation
Generally, a BSR periodically distributes the RP-set information in bootstrap messages within the IPv6
BIDIR-PIM domain. It encapsulates a BSM in an IP datagram and might split the datagram into fragments
if the message exceeds the 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
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.
The function of BSM semantic fragmentation is enabled by default. Devices not supporting this function
might deem a fragment as an entire message, thus learning only part of the RP-set information. Therefore,
if such devices exist in the IPv6 BIDIR-PIM domain, you need to disable the semantic fragmentation
function on the C-BSRs.
Use the command...
system-view
pim ipv6
c-bsr interval interval
c-bsr holdtime interval
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Remarks
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Optional.
For the default value, see below.
Optional.
For the default value, see below.