Definitions of Managed Objects for the DS0 and DS0 Bundle Interface Type
Extracted elements (21)
The dsx0BundleTable is not indexed by ifIndex because the manager must choose the index for row creation while the agent must be free to select ifIndex values independently. This separation of concerns necessitates dsx0BundleIndex as a distinct manager-chosen key.
The dsx0ChanMappingTable provides redundant information also available via ifStackTable and dsx0ConfigTable, but is justified as enabling single-lookup mapping from (channelized interface, channel number) to DS0 ifIndex rather than requiring table walks.
The dsx0Ds0BundleMappedIfIndex object duplicates information available via ifStackTable walking, but is provided to allow bundle membership to be determined with a single table lookup rather than traversing the ifStackTable.
The dsx0RobbedBitSignalling object only applies to DS0s on a DS1 link. For E1 links the value is always false (off) and cannot be set to true.
When dsx1Channelization is set to enabledDs0, 24 DS0s are created by the agent. If dsx1Channelization is set to disabled, those 24 DS0s are destroyed. Treatment of E1 is similar but with a different number of DS0s depending on framing; timeslot 16 is not created for framing types that do not pass data over it.
Only the ifGeneralInformationGroup and ifCounterDiscontinuityGroup from RFC 2233 need to be supported for DS0 and DS0Bundle interfaces. The ifLinkUpDownTrapEnable must be set to disabled(2) with read-only access, and ifConnectorPresent must be set to false(2).
The DS0 Bonding Group (dsx0BondingTable) implementation is optional for all systems that use a DS0Bundle interface. The DS0 Bundle Config Group is mandatory.
The DS0Bundle compliance statement restricts dsx0BundleRowStatus to only three RowStatus values: active(1), createAndGo(4), and destroy(6). Only createAndGo is supported for creation, preventing managers from creating inactive rows since inactive ds0Bundle rows are semantically invalid.
The DS0 MIB defines managed objects for individual DS0 channels within a DS1 or E1 interface, using ifType ds0(81). Each DS0 is represented as an entry in the ifTable, with ifSpeed set to 64000 regardless of robbed bit signalling settings.
The DS0Bundle MIB defines managed objects for collections of DS0 channels bundled together to carry data at speeds greater than a single DS0, using ifType ds0Bundle(82). The ifSpeed for a ds0Bundle is N*64000 where N is the number of constituent DS0s.
The dsx0BondMode object defines BONDing modes for a ds0Bundle: none(1), other(2), mode0(3) through mode3(6). Mode0 provides parameter/number exchange only; Mode1 adds initialization synchronization; Mode2 adds inband monitoring at 1/64th bandwidth overhead; Mode3 provides full N×56/64 kbit/s support.
The dsx0BundleNextIndex object uses the TestAndIncr textual convention to help managers select unique index values for new ds0Bundle rows and to prevent race conditions when multiple managers create rows simultaneously.
The dsx0BundleTable allows creation of DS0Bundle interfaces via SNMP row creation. Each entry contains dsx0BundleIndex (manager-chosen, not ifIndex), dsx0BundleIfIndex (agent-assigned ifIndex), dsx0BundleCircuitIdentifier, and dsx0BundleRowStatus.
The dsx0ChanMappingTable maps (DS1/E1 ifIndex, DS0 channel number) to DS0 ifIndex, facilitating lookup from channelized interface and channel number to the specific DS0 ifEntry. It is indexed by ifIndex and dsx0Ds0ChannelNumber.
The dsx0ConfigTable provides per-DS0 configuration including channel number (dsx0Ds0ChannelNumber, INTEGER 0..31), robbed bit signalling enable (dsx0RobbedBitSignalling), circuit identifier (dsx0CircuitIdentifier, DisplayString 0..255), idle/seized ABCD bit codes, and bundle mapping ifIndex.
The dsx0Ds0BundleMappedIfIndex object (InterfaceIndexOrZero, read-only) indicates the ifIndex of the ds0Bundle(82) to which a given ds0(81) belongs. A value of zero indicates the DS0 is not part of any bundle.
The dsx0IdleCode and dsx0SeizedCode objects are INTEGER(0..15) bitmaps representing the ABCD signalling bits transmitted when a DS0 is idle or connected respectively. Bit positions: 1=D, 2=C, 4=B, 8=A.
The dsx0ReceivedCode object (read-only, INTEGER 0..15) contains the ABCD bits currently being received on a DS0, using the same bitmap encoding as dsx0IdleCode and dsx0SeizedCode.
This document registers DS0-MIB under transmission(81) and DS0BUNDLE-MIB under transmission(82) in the SNMP transmission subtree, corresponding to ifType values ds0(81) and ds0Bundle(82).
SNMPv1 is inherently insecure; implementors are recommended to use SNMPv3 with the User-based Security Model (RFC 2274) and View-based Access Control Model (RFC 2275). Setting objects dsx0RobbedBitSignalling, dsx0IdleCode, dsx0SeizedCode, dsx0TransmitCodesEnable, dsx0BundleRowStatus, dsx0BondMode, or dsx0BondRowStatus to inappropriate values can cause loss of traffic.
The dsx0BondStatus object tracks bonding call state with three values: idle(1) when bonding mode is none, callSetup(2) during call establishment, and dataTransfer(3) during active data transfer.