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Hi
Su.
1. What's the purpose of pimGroupMappingPrecedence item? Is it only
used in mapping a group prefix to a static rp?
[DMcW]
If more than one RP could be used for a group, the pimGroupMappingPrecedence
chooses between them. 2. If there are static RP (embedded RP added in IPv6 multicast), BSR-RP, or some other dynamic RP mechanism like CISCO’s private AutoRP, willing to sever a group/prefix, How to choose the unique RP? [DMcW]
Each willing RP has a pimGroupMappingEntry row. The one with
the lowest numerical pimGroupMappingPrecedence is chosen.
3. Why the pimGroupMappingPrecedence appear twice in the above words(row3 and row5)? Is there any diffrence between this two rows? [DMcW]
You're right, 3 and 5 say the same thing. I think 5 has
no effect, and should be deleted. Hope
that helps,
David
McWalter.
-----Original Message-----
From: Su Haiyang [mailto:suhaiyang at huawei.com] Sent: 27 February 2007 10:43 To: suhaiyang at huawei.com Cc: pim at ietf.org Subject: [pim] Some doubts about draft-ietf-pim-mib-v2-09? Hi, I have some doubts about The PIM Group Mapping Table defined at draft draft-ietf-pim-mib-v2-09 I will appreciate your help if someone can give answer about the following doubts in page 66 of draft-ietf-pim-mib-v2-09, there are some words as bellow:
Given the collection of rows in this table at any point in time, the PIM mode and RP address to use for a particular group is determined using the following algorithm.
1. From the set of all rows, the subset whose group prefix contains the group in question are selected.
2. If there are no such rows, the behavior is undefined.
3. If there is at least one such row, from the selected subset of rows, the subset that have the lowest value of pimGroupMappingPrecedence are selected.
4. From the selected subset of rows, the subset that have the greatest value of pimGroupMappingGrpPrefixLength are selected.
5. If there are multiple selected rows, the subset that have the highest precedence (the lowest numerical value for pimGroupMappingPrecedence) are selected.
6. If there are multiple selected rows, the row selected is implementation dependent; the implementation might or might not apply the PIM hash function to select the row.
7. The group mode to use is given by the value of pimGroupMappingPimMode from the single selected row; the RP to use is given by the value of pimGroupMappingRPAddress, unless pimGroupMappingOrigin is 'embedded', in which case the RP is extracted from the group address in question."
I don’t understand these words totally: 1. What's the purpose of pimGroupMappingPrecedence item? Is it only used in mapping a group prefix to a static rp? 2. If there are static RP (embedded RP added in IPv6 multicast), BSR-RP, or some other dynamic RP mechanism like CISCO’s private AutoRP, willing to sever a group/prefix, How to choose the unique RP? 3. Why the pimGroupMappingPrecedence appear twice in the above words(row3 and row5)? Is there any diffrence between this two rows? Best Regards Steven Su
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