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Configuring C-BSR timers
The BSR election winner multicasts its own IP 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 timer, during which no BSR election takes place. If no
bootstrap message is received from the BSR when the BS timeout timer expires, a new BSR election
process is triggered among the C-BSRs.
Perform the following configuration on C-BSR routers. If you configure value for the C-BSR timers,
the system uses the configured ones instead of the default ones.
To configure C-BSR timers:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter public network PIM
view or VPN instance PIM
view.
pim
[
vpn-instance
vpn-instance-name
]
N/A
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 is 60 × 2 + 10 = 130
(seconds).
Disabling BSM semantic fragmentation
Generally, a BSR periodically distributes the RP-set information in bootstrap messages within the
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
does 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 due to learning of a new PIM neighbor is
performed according to the MTU of the outgoing interface.
