H3C Technologies H3C S12500-X Series Switches - Manual (Page 88)

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Step Command Remarks
1. Enter system view. system-view N/A
2. Enter PIM view.
pim [ vpn-instance
vpn-instance-name ]
N/A
3. Configure a C-BSR.
c-bsr ip-address [ scope
group-address { mask-length |
mask } ] [ hash-length hash-length
| priority priority ] *
By default, no C-BSR is configured.
4. (Optional.) Configure a legal
BSR address range.
bsr-policy acl-number
By default, no restrictions are
defined.
Configuring a PIM domain border
As the administrative core of a PIM-SM domain, the BSR sends the collected RP-set information in the form
of bootstrap messages to all routers in the PIM-SM domain.
A PIM domain border is a bootstrap message boundary. Each BSR has its specific service scope. A
number of PIM domain border interfaces partition a network into different PIM-SM domains. Bootstrap
messages cannot cross a domain border in either direction.
Perform the following configuration on routers that you want to configure as a PIM domain border.
To configure a PIM domain border:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view.
interface interface-type
interface-number
N/A
3. Configure a PIM domain
border.
pim bsr-boundary
By default, no PIM domain border
is configured.
Disabling the BSM semantic fragmentation function
Generally, a BSR periodically advertises the RP-set information in BSMs within the PIM-SM domain. It
encapsulates a BSM in an IP datagram and might fragment the datagram if the message exceeds the
MTU. In this case, 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
BSM fragments (BSMFs).
• If the RP-set information for a multicast group range is carried in one BSMF, a non-BSR router directly
updates the RP-set information for the group range after receiving the BSMF.
• If the RP-set information for a multicast group range is carried in multiple BSMFs, a non-BSR router
updates the RP-set information for the group range after receiving all these BSMFs. Because the
RP-set information contained in each fragment is different, loss of some IP fragments does not result
in dropping of the entire BSM.
The BSM semantic fragmentation function is enabled by default. A device that does not support this
function might regard a fragment as a BSM and thus learns only part of the RP-set information. Therefore,
if such devices exist in the PIM-SM domain, you must disable the BSM semantic fragmentation function on
the C-BSRs.
To disable the BSM semantic fragmentation function: