4.2. Updating an Implementation of the IPv6-MIB
4.2. Updating an Implementation of the IPv6-MIB
The somewhat more specific changes that are required for IPv6 follow. Note well: this is not meant to be an exhaustive list and the reader should examine the MIB for full details.
Two of the general objects, ipv6Forwarding and ipv6DefaultHopLimit, have been renamed and given new object identifiers within the ip branch but are otherwise unchanged. The new names are ipv6IpForwarding and ipv6IpDefaultHopLimit.
While there is an ipv6InterfaceTable that contains some of the pieces from the ipv6IfTable, the two are somewhat different in concept. The ipv6IfTable was meant to replicate the ifTable while the ipv6InterfaceTable is meant to be an addition to the ifTable. As such, items that were duplicated between the ifTable and ipv6IfTable have been removed and some new objects added.
The ipv6IfStatsTable most closely resembles the ipIfStatsTable with an additional index for the address type and most of the instrumentation should be re-usable. Some new objects have been added to the ipIfStatsTable. As above, the SNMP routines will need to be updated to handle the new indexing. Finally, the ipIfStatsTable is optional and may be ignored.
The ipSystemStatsTable is effectively new, but it may be able to make use of most of the instrumentation from the old ipv6IfStatsTable. As with the IPv4 discussion, one implementation strategy would be to count the statistics for the ipIfStatsTable and aggregate them when queried for this table. Again, as with the IPv4 discussion, this strategy only works if the interfaces cannot be removed or if the statistics for removed interfaces are somehow retained.
The ipv6AddrPrefixTable is now the ipAddressPrefixTable. The new table contains an extra object and the additional index required for IPv4 compatibility. As above, the SNMP routines will need to be updated to handle the new indexing.
The ipAddressTable is loosely based on the ipv6AddrTable but has changed considerably with the addition of several new objects and the removal of one of its indexes.
The IPv6 routing information (ipv6RouteNumber, ipv6DiscardedRoutes, and ipv6RouteTable) has been removed from this MIB. The replacements or updates for this information is in the update to the IP Forwarding Table MIB [16]. The ipv6NetToMediaTable has been converted to the ipNetToPhysicalTable. The new table contains an extra object and the additional index required for IPv4 compatibility. As above, the SNMP routines will need to be updated to handle the new indexing.
The ICMP tables have been substantially changed. The previous tables required counting on a per-message and per-interface basis. The new tables only require counting on a per-message, per-protocol basis and include an aggregate of all messages on a per-protocol basis.
In addition to the above, several new tables have been added. Both the ipv6ScopeZoneIndexTable and ipDefaultRouterTable are required on all IPv6 entities. The ipv6RouterAdvertTable is only required on IPv6 routers.