Description:
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alaPimGroupMappingTable OBJECT-TYPE
SYNTAX SEQUENCE OF AlaPimGroupMappingEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The (conceptual) table listing mappings from multicast
group prefixes to the PIM mode and RP address to use for
groups within that group prefix.
Rows in this table are created for a variety of reasons,
indicated by the value of the alaPimGroupMappingOrigin object.
- Rows with a alaPimGroupMappingOrigin value of 'fixed' are
created automatically by the router at startup, to
correspond to the well-defined prefixes of link-local and
unroutable group addresses. These rows are never
destroyed.
- Rows with a alaPimGroupMappingOrigin value of 'embedded' are
created by the router to correspond to group prefixes
that are to be treated as being in Embedded-RP format.
- Rows with a alaPimGroupMappingOrigin value of 'configRp' are
created and destroyed as a result of rows in the
alaPimStaticRPTable being created and destroyed.
- Rows with a alaPimGroupMappingOrigin value of 'configSsm'
are created and destroyed as a result of configuration of
SSM address ranges to the local router.
- Rows with a alaPimGroupMappingOrigin value of 'bsr' are
created as a result of running the PIM Bootstrap Router
(BSR) mechanism. If the local router is not the elected
BSR, these rows are created to correspond to group
prefixes in the PIM Bootstrap messages received from the
elected BSR. If the local router is the elected BSR,
these rows are created to correspond to group prefixes in
the PIM Bootstrap messages that the local router sends.
In either case, these rows are destroyed when the group
prefixes are timed out by the BSR mechanism.
- Rows with a alaPimGroupMappingOrigin value of 'other' are
created and destroyed according to some other mechanism
not specified here.
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. From the selected subset of rows, the subset that have
the greatest value of alaPimGroupMappingGrpPrefixLength are
selected.
4. If there are multiple selected rows, and a subset are
defined by alaPimStaticRPTable (alaPimGroupMappingOrigin value
of 'configRp') with alaPimStaticRPOverrideDynanic set to
TRUE, then this subset is selected.
5. If there are still multiple selected rows, the subset
that have the highest precedence (the lowest numerical
value for alaPimGroupMappingPrecedence) are selected.
6. If there are still 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
alaPimGroupMappingPimMode from the single selected row; the
RP to use is given by the value of
alaPimGroupMappingRPAddress, unless alaPimGroupMappingOrigin is
'embedded', in which case the RP is extracted from the
group address in question."
REFERENCE
"RFC 4601 section 3.7, RFC 3956 and RFC 4610"
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