PTOPO-MIB

TimeFilterTo be used for the index to a table. Allows an application to download only those rows changed since a particular time. Note that this is not a history mechanism. Only current values of underlying objects are returned; saved instance values associated with particular values of sysUpTime are not. An entry is considered changed if the value of any object in the entry changes, if the row is created, or if any object in the entry is created or deleted. Note that deleted entries cannot be detected or downloaded. A time-filtered conceptual table is created by inserting a single object of SYNTAX TimeFilter as the first INDEX component in a copy of an existing basic conceptual table (i.e., any SEQUENCE without a TimeFilter INDEX component). Thus, for each conceptual entry 'I' in the basic table, there exists N conceptual entries in the time-filtered version, indexed N.I, where 'N' is equal to the value of sysUpTime. When an application retrieves conceptual instances from a time-filtered table, and an INDEX value is provided for the TimeFilter INDEX component 'N', the agent will only consider returning basic conceptual entries (e.g., 'fooColumn.N.I') if any column within the basic conceptual entry has changed since sysUpTime 'N'. If not, the basic conceptual entry will be ignored for the particular retrieval operation. When sysUpTime is equal to zero, this table shall be empty. One conceptual entry exists for each past value of sysUpTime, except that the whole table is purged should sysUpTime wrap. As an entry in a time-filtered table is updated (i.e., one of the columns in the basic conceptual table is changed), new conceptual entries are also created in the time-filtered version (which still shares the now updated object values with all other instances). The number of unique time-filtered instances that are created is determined by the value of sysUpTime at which the basic entry was last updated. One unique instance will exist for each value of sysUpTime at the last update time for the row. However, a new TimeFilter index instance is created for each new sysUpTime value. The TimeFilter index values not associated with entry updates are called duplicate time-filtered instances. After some deployment experience, it has been determined that a time-filtered table is more efficient if the agent stops a MIB walk operation by skipping over rows with a TimeFilter index value higher than the value in the received GetNext/GetBulk request. That is, instead of incrementing a TimeFilter index value, the agent will continue to the next object or table. As a consequence, GetNext or GetBulk operations will provide only one pass through a time-filtered table. It is suggested that an agent implement a time-filtered table in this manner to improve performance and avoid a MIB walk getting stuck in time-filtered tables. It is, however, still acceptable for an agent to implement a time-filtered table in the traditional manner (i.e., every conceptual time-filtered instance is returned in GetNext and GetBulk PDU responses), and management applications must be able to deal with such traditional implementations. See the appendix for further discussion of this textual convention. The following example is provided to demonstrate TimeFilter behavior: Consider the following basic conceptual table, basicFooTable. (Note that the basic version of a time-filtered table may not actually be defined.) basicFooTable: basicFooTable ... INDEX { fooIndex } BasicFooEntry { fooIndex Integer32, fooCounts Counter32 } For this example, the basicFooTable contains two static conceptual entries (fooIndex equals '1' and '2'), created at time zero. It also contains one dynamic conceptual entry (fooIndex equals '3'), which is created at time '3' and deleted at time '7'. The time-filtered version of the basicFooTable could be defined as follows: FooTable: fooTable ... INDEX { fooTimeMark, fooIndex } FooEntry { fooTimeMark TimeFilter, fooIndex Integer32, fooCounts Counter32 } Note that entries exist in the time-filtered conceptual table only if they actually exist in the underlying (basic) table. For this example, the fooTable will have three underlying basic entries (fooIndex == 1, 2, and 3), with the following activity (for sysUpTime equal 0 to 9): - fooEntry.N.1 is created at time '0' and most recently updated at time '6' to the value '5'. - fooEntry.N.2 is created at time '0' and most recently updated at time '8' to the value '9'. - fooEntry.N.3 is created at time '3', updated at time '5' to the value '17', and deleted at time '7'. The following tables show the values that would be returned for MIB walk operations with various TimeFilter values, done at different times. An application issues a retrieval request at time 'T', with a TimeFilter value, 'N' (typically set to a lower value, such as the value of sysUpTime at the last polling cycle). The following values would be returned in a MIB walk of fooCounts.N if T equals '0' and N equals '0': fooCounts.N.I Value ========================== fooCounts.0.1 0 fooCounts.0.2 0 Note that nothing is returned for fooCounts.0.3, since that entry does not exist at sysUpTime equals '0'. The following values would be returned in a full (traditional) MIB walk of fooCounts.N if T equals '3' and N equals '0': fooCounts.N.I Value ======================= fooCounts.0.1 0 fooCounts.0.2 0 fooCounts.0.3 0 fooCounts.1.3 0 fooCounts.2.3 0 fooCounts.3.3 0 Note that there are no instances for T equals 1 or 2 for the first two values of N, as these entries did not change since they were created at time '0'. Note that the current value for 'fooCounts.N.3' is returned here, even for values of N less than '3' (when the entry was created). The agent only considers the current existence of an entry in the TimeFilter algorithm, not the time when the entry was created. Note that the instances 'fooCounts.0.3', 'fooCounts.1.3', and 'fooCounts.2.3' are duplicates and can be suppressed by the agent in a MIB walk. The following values would be returned in a full (traditional) MIB walk of fooCounts.N if T equals '6' and N equals '3': fooCounts.N.I Value ======================= fooCounts.3.1 5 fooCounts.3.3 17 fooCounts.4.1 5 fooCounts.4.3 17 fooCounts.5.1 5 fooCounts.5.3 17 fooCounts.6.1 5 Note that no instances for entry 'fooCounts.N.2' are returned, since it has not changed since time '3'. Note that all instances except 'fooCounts.5.3' and 'fooCounts.6.1' are duplicates and can be suppressed by the agent in a MIB walk. The following values would be returned in a full (traditional) MIB walk of fooCounts.N if T equals '9' and N equals '6': fooCounts.N.I Value ======================= fooCounts.6.1 5 fooCounts.6.2 9 fooCounts.7.2 9 fooCounts.8.2 9 Note that no instances for entry 'fooCounts.N.3' are returned, since it was deleted at time '7'. Note that instances 'fooCounts.6.2' and 'fooCounts.7.2' are duplicates and can be suppressed by the agent in a MIB walk. · TimeTicks

A TimeFilter for this entry. See the TimeFilter textual convention in RFC 2021 to see how this works.

PhysicalIndexAn arbitrary value that uniquely identifies the physical entity. The value should be a small positive integer. Index values for different physical entities are not necessarily contiguous. (1..2147483647) · Integer32 · hint d

The entPhysicalIndex value used to identify the chassis component associated with the local connection endpoint.

PhysicalIndexAn arbitrary value that uniquely identifies the physical entity. The value should be a small positive integer. Index values for different physical entities are not necessarily contiguous. (1..2147483647) · Integer32 · hint d

The entPhysicalIndex value used to identify the port component associated with the local connection endpoint.

Integer32 (1..2147483647)

This object represents an arbitrary local integer value used by this agent to identify a particular connection instance, unique only for the indicated local connection endpoint. A particular ptopoConnIndex value may be reused in the event an entry is aged out and later re-learned with the same (or different) remote chassis and port identifiers. An agent is encouraged to assign monotonically increasing index values to new entries, starting with one, after each reboot. It is considered unlikely that the ptopoConnIndex will wrap between reboots.

PtopoChassisIdType1 = chasIdEntPhysicalAlias2 = chasIdIfAlias3 = chasIdPortEntPhysicalAlias4 = chasIdMacAddress5 = chasIdPtopoGenAddrThis TC describes the source of a chassis identifier. The enumeration 'chasIdEntPhysicalAlias(1)' represents a chassis identifier based on the value of entPhysicalAlias for a chassis component (i.e., an entPhysicalClass value of 'chassis(3)'). The enumeration 'chasIdIfAlias(2)' represents a chassis identifier based on the value of ifAlias for an interface on the containing chassis. The enumeration 'chasIdPortEntPhysicalAlias(3)' represents a chassis identifier based on the value of entPhysicalAlias for a port or backplane component (i.e., entPhysicalClass value of 'port(10)' or 'backplane(4)'), within the containing chassis. The enumeration 'chasIdMacAddress(4)' represents a chassis identifier based on the value of a unicast source MAC address (encoded in network byte order and IEEE 802.3 canonical bit order), of a port on the containing chassis. The enumeration 'chasIdPtopoGenAddr(5)' represents a chassis identifier based on a network address, associated with a particular chassis. The encoded address is actually composed of two fields. The first field is a single octet, representing the IANA AddressFamilyNumbers value for the specific address type, and the second field is the PtopoGenAddr address value. · Integer32

The type of encoding used to identify the chassis associated with the remote connection endpoint. This object may not be modified if the associated ptopoConnRowStatus object has a value of active(1).

PtopoChassisIdThis TC describes the format of a chassis identifier string. Objects of this type are always used with an associated PtopoChassisIdType object, which identifies the format of the particular PtopoChassisId object instance. If the associated PtopoChassisIdType object has a value of 'chasIdEntPhysicalAlias(1)', then the octet string identifies a particular instance of the entPhysicalAlias object for a chassis component (i.e., an entPhysicalClass value of 'chassis(3)'). If the associated PtopoChassisIdType object has a value of 'chasIdIfAlias(2)', then the octet string identifies a particular instance of the ifAlias object for an interface on the containing chassis. If the associated PtopoChassisIdType object has a value of 'chasIdPortEntPhysicalAlias(3)', then the octet string identifies a particular instance of the entPhysicalAlias object for a port or backplane component within the containing chassis. If the associated PtopoChassisIdType object has a value of 'chasIdMacAddress(4)', then this string identifies a particular unicast source MAC address (encoded in network byte order and IEEE 802.3 canonical bit order), of a port on the containing chassis. If the associated PtopoChassisIdType object has a value of 'chasIdPtopoGenAddr(5)', then this string identifies a particular network address, encoded in network byte order, associated with one or more ports on the containing chassis. The first octet contains the IANA Address Family Numbers enumeration value for the specific address type, and octets 2 through N contain the PtopoGenAddr address value in network byte order. SIZE (1..32) · OCTET STRING

The string value used to identify the chassis component associated with the remote connection endpoint. This object may not be modified if the associated ptopoConnRowStatus object has a value of active(1).

PtopoPortIdType1 = portIdIfAlias2 = portIdEntPhysicalAlias3 = portIdMacAddr4 = portIdPtopoGenAddrThis TC describes the source of a particular type of port identifier used in the PTOPO MIB. The enumeration 'portIdIfAlias(1)' represents a port identifier based on the ifAlias MIB object. The enumeration 'portIdPortEntPhysicalAlias(2)' represents a port identifier based on the value of entPhysicalAlias for a port or backplane component (i.e., entPhysicalClass value of 'port(10)' or 'backplane(4)'), within the containing chassis. The enumeration 'portIdMacAddr(3)' represents a port identifier based on a unicast source MAC address, which has been detected by the agent and associated with a particular port. The enumeration 'portIdPtopoGenAddr(4)' represents a port identifier based on a network address, detected by the agent and associated with a particular port. · Integer32

The type of port identifier encoding used in the associated 'ptopoConnRemotePort' object. This object may not be modified if the associated ptopoConnRowStatus object has a value of active(1).

PtopoPortIdThis TC describes the format of a port identifier string. Objects of this type are always used with an associated PtopoPortIdType object, which identifies the format of the particular PtopoPortId object instance. If the associated PtopoPortIdType object has a value of 'portIdIfAlias(1)', then the octet string identifies a particular instance of the ifAlias object. If the associated PtopoPortIdType object has a value of 'portIdEntPhysicalAlias(2)', then the octet string identifies a particular instance of the entPhysicalAlias object for a port component (i.e., entPhysicalClass value of 'port(10)'). If the associated PtopoPortIdType object has a value of 'portIdMacAddr(3)', then this string identifies a particular unicast source MAC address associated with the port. If the associated PtopoPortIdType object has a value of 'portIdPtopoGenAddr(4)', then this string identifies a network address associated with the port. The first octet contains the IANA AddressFamilyNumbers enumeration value for the specific address type, and octets 2 through N contain the PtopoGenAddr address value in network byte order. SIZE (1..32) · OCTET STRING

The string value used to identify the port component associated with the remote connection endpoint. This object may not be modified if the associated ptopoConnRowStatus object has a value of active(1).

AutonomousTypeRepresents an independently extensible type identification value. It may, for example, indicate a particular sub-tree with further MIB definitions, or define a particular type of protocol or hardware. · OBJECT IDENTIFIER

An indication of the algorithm used to discover the information contained in this conceptual row. A value of ptopoDiscoveryLocal indicates this entry was configured by the local agent, without use of a discovery protocol. A value of { 0 0 } indicates this entry was created manually by an NMS via the associated RowStatus object.

AddressFamilyNumbers0 = other1 = ipV42 = ipV63 = nsap4 = hdlc5 = bbn18226 = all8027 = e1638 = e1649 = f6910 = x12111 = ipx12 = appleTalk13 = decnetIV14 = banyanVines15 = e164withNsap16 = dns17 = distinguishedName18 = asNumber19 = xtpOverIpv420 = xtpOverIpv621 = xtpNativeModeXTP22 = fibreChannelWWPN23 = fibreChannelWWNN24 = gwid25 = afi26 = mplsTpSectionEndpointIdentifier27 = mplsTpLspEndpointIdentifier28 = mplsTpPseudowireEndpointIdentifier16384 = eigrpCommonServiceFamily16385 = eigrpIpv4ServiceFamily16386 = eigrpIpv6ServiceFamily16387 = lispCanonicalAddressFormat16388 = bgpLs16389 = fortyeightBitMac16390 = sixtyfourBitMac16391 = oui16392 = mac2416393 = mac4016394 = ipv66416395 = rBridgePortID16396 = trillNickname16397 = universallyUniqueIdentifier65535 = reservedThe definition of this textual convention with the addition of newly assigned values is published periodically by the IANA, in either the Assigned Numbers RFC, or some derivative of it specific to Internet Network Management number assignments. (The latest arrangements can be obtained by contacting the IANA.) The enumerations are described as: other(0), -- none of the following ipV4(1), -- IP Version 4 ipV6(2), -- IP Version 6 nsap(3), -- NSAP hdlc(4), -- (8-bit multidrop) bbn1822(5), all802(6), -- (includes all 802 media -- plus Ethernet 'canonical format') e163(7), e164(8), -- (SMDS, Frame Relay, ATM) f69(9), -- (Telex) x121(10), -- (X.25, Frame Relay) ipx(11), -- IPX (Internet Protocol Exchange) appleTalk(12), -- Apple Talk decnetIV(13), -- DEC Net Phase IV banyanVines(14), -- Banyan Vines e164withNsap(15), -- (E.164 with NSAP format subaddress) dns(16), -- (Domain Name System) distinguishedName(17), -- (Distinguished Name, per X.500) asNumber(18), -- (16-bit quantity, per the AS number space) xtpOverIpv4(19), -- XTP over IP version 4 xtpOverIpv6(20), -- XTP over IP version 6 xtpNativeModeXTP(21), -- XTP native mode XTP fibreChannelWWPN(22), -- Fibre Channel World-Wide Port Name fibreChannelWWNN(23), -- Fibre Channel World-Wide Node Name gwid(24), -- Gateway Identifier afi(25), -- AFI for L2VPN information mplsTpSectionEndpointIdentifier(26), -- MPLS-TP Section Endpoint Identifier mplsTpLspEndpointIdentifier(27), -- MPLS-TP LSP Endpoint Identifier mplsTpPseudowireEndpointIdentifier(28), -- MPLS-TP Pseudowire Endpoint Identifier eigrpCommonServiceFamily(16384), -- EIGRP Common Service Family eigrpIpv4ServiceFamily(16385), -- EIGRP IPv4 Service Family eigrpIpv6ServiceFamily(16386), -- EIGRP IPv6 Service Family lispCanonicalAddressFormat(16387), -- LISP Canonical Address Format (LCAF) bgpLs(16388), -- BGP-LS fortyeightBitMacBitMac(16389), -- 48-bit MAC sixtyfourBitMac(16390), -- 64-bit MAC oui(16391), -- OUI mac24(16392), -- MAC/24 mac40(16393), -- MAC/40 ipv664(16394), -- IPv6/64 rBridgePortID(16395), -- RBridge Port ID trillNickname(16396), -- TRILL Nickname universallyUniqueIdentifier(16397), -- Universally Unique Identifier (UUID) reserved(65535) Requests for new values should be made to IANA via email (iana&iana.org). · Integer32

This network address type of the associated ptopoConnNetAddr object, unless that object contains a zero length string. In such a case, an NMS application should ignore any returned value for this object. This object may not be modified if the associated ptopoConnRowStatus object has a value of active(1).

PtopoGenAddrThe value of an address. SIZE (0..20) · OCTET STRING

This object identifies a network address which may be used to reach an SNMP agent entity containing information for the chassis and port components represented by the associated 'ptopoConnRemoteChassis' and 'ptopoConnRemotePort' objects. If no such address is known, then this object shall contain an empty string. This object may not be modified if the associated ptopoConnRowStatus object has a value of active(1).

PtopoAddrSeenState1 = notUsed2 = unknown3 = oneAddr4 = multiAddrThis TC describes the state of address detection for a particular type of port identifier used in the PTOPO MIB. The enumeration 'notUsed(1)' represents an entry for which the particular MIB object is not applicable to the remote connection endpoint, The enumeration 'unknown(2)' represents an entry for which the particular address collection state is not known. The enumeration 'oneAddr(3)' represents an entry for which exactly one source address (of the type indicated by the particular MIB object), has been detected. The enumeration 'multiAddr(4)' represents an entry for which more than one source address (of the type indicated by the particular MIB object), has been detected. An agent is expected to set the initial state of the PtopoAddrSeenState to 'notUsed(1)' or 'unknown(2)'. Note that the PTOPO MIB does not restrict or specify the means in which the PtopoAddrSeenState is known to an agent. In particular, an agent may detect this information through configuration data, or some means other than directly monitoring all port traffic. · Integer32

This object indicates if multiple unicast source MAC addresses have been detected by the agent from the remote connection endpoint, since the creation of this entry. If this entry has an associated ptopoConnRemoteChassisType and/or ptopoConnRemotePortType value other than 'portIdMacAddr(3)', then the value 'notUsed(1)' is returned. Otherwise, one of the following conditions must be true: If the agent has not yet detected any unicast source MAC addresses from the remote port, then the value 'unknown(2)' is returned. If the agent has detected exactly one unicast source MAC address from the remote port, then the value 'oneAddr(3)' is returned. If the agent has detected more than one unicast source MAC address from the remote port, then the value 'multiAddr(4)' is returned.

PtopoAddrSeenState1 = notUsed2 = unknown3 = oneAddr4 = multiAddrThis TC describes the state of address detection for a particular type of port identifier used in the PTOPO MIB. The enumeration 'notUsed(1)' represents an entry for which the particular MIB object is not applicable to the remote connection endpoint, The enumeration 'unknown(2)' represents an entry for which the particular address collection state is not known. The enumeration 'oneAddr(3)' represents an entry for which exactly one source address (of the type indicated by the particular MIB object), has been detected. The enumeration 'multiAddr(4)' represents an entry for which more than one source address (of the type indicated by the particular MIB object), has been detected. An agent is expected to set the initial state of the PtopoAddrSeenState to 'notUsed(1)' or 'unknown(2)'. Note that the PTOPO MIB does not restrict or specify the means in which the PtopoAddrSeenState is known to an agent. In particular, an agent may detect this information through configuration data, or some means other than directly monitoring all port traffic. · Integer32

This object indicates if multiple network layer source addresses have been detected by the agent from the remote connection endpoint, since the creation of this entry. If this entry has an associated ptopoConnRemoteChassisType or ptopoConnRemotePortType value other than 'portIdGenAddr(4)' then the value 'notUsed(1)' is returned. Otherwise, one of the following conditions must be true: If the agent has not yet detected any network source addresses of the appropriate type from the remote port, then the value 'unknown(2)' is returned. If the agent has detected exactly one network source address of the appropriate type from the remote port, then the value 'oneAddr(3)' is returned. If the agent has detected more than one network source address (of the same appropriate type) from the remote port, this the value 'multiAddr(4)' is returned.

TruthValue1 = true2 = falseRepresents a boolean value. · Integer32

This object identifies static ptopoConnEntries. If this object has the value 'true(1)', then this entry is not subject to any age-out mechanisms implemented by the agent. If this object has the value 'false(2)', then this entry is subject to all age-out mechanisms implemented by the agent. This object may not be modified if the associated ptopoConnRowStatus object has a value of active(1).

TimeStampThe value of the sysUpTime object at which a specific occurrence happened. The specific occurrence must be defined in the description of any object defined using this type. If sysUpTime is reset to zero as a result of a re- initialization of the network management (sub)system, then the values of all TimeStamp objects are also reset. However, after approximately 497 days without a re- initialization, the sysUpTime object will reach 2^^32-1 and then increment around to zero; in this case, existing values of TimeStamp objects do not change. This can lead to ambiguities in the value of TimeStamp objects. · TimeTicks

If the associated value of ptopoConnIsStatic is equal to 'false(2)', then this object contains the value of sysUpTime at the time the conceptual row was last verified by the agent, e.g., via reception of a topology protocol message, pertaining to the associated remote chassis and port. If the associated value of ptopoConnIsStatic is equal to 'true(1)', then this object shall contain the value of sysUpTime at the time this entry was last activated (i.e., ptopoConnRowStatus set to 'active(1)').

RowStatus1 = active2 = notInService3 = notReady4 = createAndGo5 = createAndWait6 = destroyThe RowStatus textual convention is used to manage the creation and deletion of conceptual rows, and is used as the value of the SYNTAX clause for the status column of a conceptual row (as described in Section 7.7.1 of [2].) The status column has six defined values: - `active', which indicates that the conceptual row is available for use by the managed device; - `notInService', which indicates that the conceptual row exists in the agent, but is unavailable for use by the managed device (see NOTE below); 'notInService' has no implication regarding the internal consistency of the row, availability of resources, or consistency with the current state of the managed device; - `notReady', which indicates that the conceptual row exists in the agent, but is missing information necessary in order to be available for use by the managed device (i.e., one or more required columns in the conceptual row have not been instanciated); - `createAndGo', which is supplied by a management station wishing to create a new instance of a conceptual row and to have its status automatically set to active, making it available for use by the managed device; - `createAndWait', which is supplied by a management station wishing to create a new instance of a conceptual row (but not make it available for use by the managed device); and, - `destroy', which is supplied by a management station wishing to delete all of the instances associated with an existing conceptual row. Whereas five of the six values (all except `notReady') may be specified in a management protocol set operation, only three values will be returned in response to a management protocol retrieval operation: `notReady', `notInService' or `active'. That is, when queried, an existing conceptual row has only three states: it is either available for use by the managed device (the status column has value `active'); it is not available for use by the managed device, though the agent has sufficient information to attempt to make it so (the status column has value `notInService'); or, it is not available for use by the managed device, and an attempt to make it so would fail because the agent has insufficient information (the state column has value `notReady'). NOTE WELL This textual convention may be used for a MIB table, irrespective of whether the values of that table's conceptual rows are able to be modified while it is active, or whether its conceptual rows must be taken out of service in order to be modified. That is, it is the responsibility of the DESCRIPTION clause of the status column to specify whether the status column must not be `active' in order for the value of some other column of the same conceptual row to be modified. If such a specification is made, affected columns may be changed by an SNMP set PDU if the RowStatus would not be equal to `active' either immediately before or after processing the PDU. In other words, if the PDU also contained a varbind that would change the RowStatus value, the column in question may be changed if the RowStatus was not equal to `active' as the PDU was received, or if the varbind sets the status to a value other than 'active'. Also note that whenever any elements of a row exist, the RowStatus column must also exist. To summarize the effect of having a conceptual row with a status column having a SYNTAX clause value of RowStatus, consider the following state diagram: STATE +--------------+-----------+-------------+------------- | A | B | C | D | |status col.|status column| |status column | is | is |status column ACTION |does not exist| notReady | notInService| is active --------------+--------------+-----------+-------------+------------- set status |noError ->D|inconsist- |inconsistent-|inconsistent- column to | or | entValue| Value| Value createAndGo |inconsistent- | | | | Value| | | --------------+--------------+-----------+-------------+------------- set status |noError see 1|inconsist- |inconsistent-|inconsistent- column to | or | entValue| Value| Value createAndWait |wrongValue | | | --------------+--------------+-----------+-------------+------------- set status |inconsistent- |inconsist- |noError |noError column to | Value| entValue| | active | | | | | | or | | | | | | | |see 2 ->D|see 8 ->D| ->D --------------+--------------+-----------+-------------+------------- set status |inconsistent- |inconsist- |noError |noError ->C column to | Value| entValue| | notInService | | | | | | or | | or | | | | | |see 3 ->C| ->C|see 6 --------------+--------------+-----------+-------------+------------- set status |noError |noError |noError |noError ->A column to | | | | or destroy | ->A| ->A| ->A|see 7 --------------+--------------+-----------+-------------+------------- set any other |see 4 |noError |noError |see 5 column to some| | | | value | | see 1| ->C| ->D --------------+--------------+-----------+-------------+------------- (1) goto B or C, depending on information available to the agent. (2) if other variable bindings included in the same PDU, provide values for all columns which are missing but required, and all columns have acceptable values, then return noError and goto D. (3) if other variable bindings included in the same PDU, provide legal values for all columns which are missing but required, then return noError and goto C. (4) at the discretion of the agent, the return value may be either: inconsistentName: because the agent does not choose to create such an instance when the corresponding RowStatus instance does not exist, or inconsistentValue: if the supplied value is inconsistent with the state of some other MIB object's value, or noError: because the agent chooses to create the instance. If noError is returned, then the instance of the status column must also be created, and the new state is B or C, depending on the information available to the agent. If inconsistentName or inconsistentValue is returned, the row remains in state A. (5) depending on the MIB definition for the column/table, either noError or inconsistentValue may be returned. (6) the return value can indicate one of the following errors: wrongValue: because the agent does not support notInService (e.g., an agent which does not support createAndWait), or inconsistentValue: because the agent is unable to take the row out of service at this time, perhaps because it is in use and cannot be de-activated. (7) the return value can indicate the following error: inconsistentValue: because the agent is unable to remove the row at this time, perhaps because it is in use and cannot be de-activated. (8) the transition to D can fail, e.g., if the values of the conceptual row are inconsistent, then the error code would be inconsistentValue. NOTE: Other processing of (this and other varbinds of) the set request may result in a response other than noError being returned, e.g., wrongValue, noCreation, etc. Conceptual Row Creation There are four potential interactions when creating a conceptual row: selecting an instance-identifier which is not in use; creating the conceptual row; initializing any objects for which the agent does not supply a default; and, making the conceptual row available for use by the managed device. Interaction 1: Selecting an Instance-Identifier The algorithm used to select an instance-identifier varies for each conceptual row. In some cases, the instance- identifier is semantically significant, e.g., the destination address of a route, and a management station selects the instance-identifier according to the semantics. In other cases, the instance-identifier is used solely to distinguish conceptual rows, and a management station without specific knowledge of the conceptual row might examine the instances present in order to determine an unused instance-identifier. (This approach may be used, but it is often highly sub-optimal; however, it is also a questionable practice for a naive management station to attempt conceptual row creation.) Alternately, the MIB module which defines the conceptual row might provide one or more objects which provide assistance in determining an unused instance-identifier. For example, if the conceptual row is indexed by an integer-value, then an object having an integer-valued SYNTAX clause might be defined for such a purpose, allowing a management station to issue a management protocol retrieval operation. In order to avoid unnecessary collisions between competing management stations, `adjacent' retrievals of this object should be different. Finally, the management station could select a pseudo-random number to use as the index. In the event that this index was already in use and an inconsistentValue was returned in response to the management protocol set operation, the management station should simply select a new pseudo-random number and retry the operation. A MIB designer should choose between the two latter algorithms based on the size of the table (and therefore the efficiency of each algorithm). For tables in which a large number of entries are expected, it is recommended that a MIB object be defined that returns an acceptable index for creation. For tables with small numbers of entries, it is recommended that the latter pseudo-random index mechanism be used. Interaction 2: Creating the Conceptual Row Once an unused instance-identifier has been selected, the management station determines if it wishes to create and activate the conceptual row in one transaction or in a negotiated set of interactions. Interaction 2a: Creating and Activating the Conceptual Row The management station must first determine the column requirements, i.e., it must determine those columns for which it must or must not provide values. Depending on the complexity of the table and the management station's knowledge of the agent's capabilities, this determination can be made locally by the management station. Alternately, the management station issues a management protocol get operation to examine all columns in the conceptual row that it wishes to create. In response, for each column, there are three possible outcomes: - a value is returned, indicating that some other management station has already created this conceptual row. We return to interaction 1. - the exception `noSuchInstance' is returned, indicating that the agent implements the object-type associated with this column, and that this column in at least one conceptual row would be accessible in the MIB view used by the retrieval were it to exist. For those columns to which the agent provides read-create access, the `noSuchInstance' exception tells the management station that it should supply a value for this column when the conceptual row is to be created. - the exception `noSuchObject' is returned, indicating that the agent does not implement the object-type associated with this column or that there is no conceptual row for which this column would be accessible in the MIB view used by the retrieval. As such, the management station can not issue any management protocol set operations to create an instance of this column. Once the column requirements have been determined, a management protocol set operation is accordingly issued. This operation also sets the new instance of the status column to `createAndGo'. When the agent processes the set operation, it verifies that it has sufficient information to make the conceptual row available for use by the managed device. The information available to the agent is provided by two sources: the management protocol set operation which creates the conceptual row, and, implementation-specific defaults supplied by the agent (note that an agent must provide implementation-specific defaults for at least those objects which it implements as read-only). If there is sufficient information available, then the conceptual row is created, a `noError' response is returned, the status column is set to `active', and no further interactions are necessary (i.e., interactions 3 and 4 are skipped). If there is insufficient information, then the conceptual row is not created, and the set operation fails with an error of `inconsistentValue'. On this error, the management station can issue a management protocol retrieval operation to determine if this was because it failed to specify a value for a required column, or, because the selected instance of the status column already existed. In the latter case, we return to interaction 1. In the former case, the management station can re-issue the set operation with the additional information, or begin interaction 2 again using `createAndWait' in order to negotiate creation of the conceptual row. NOTE WELL Regardless of the method used to determine the column requirements, it is possible that the management station might deem a column necessary when, in fact, the agent will not allow that particular columnar instance to be created or written. In this case, the management protocol set operation will fail with an error such as `noCreation' or `notWritable'. In this case, the management station decides whether it needs to be able to set a value for that particular columnar instance. If not, the management station re-issues the management protocol set operation, but without setting a value for that particular columnar instance; otherwise, the management station aborts the row creation algorithm. Interaction 2b: Negotiating the Creation of the Conceptual Row The management station issues a management protocol set operation which sets the desired instance of the status column to `createAndWait'. If the agent is unwilling to process a request of this sort, the set operation fails with an error of `wrongValue'. (As a consequence, such an agent must be prepared to accept a single management protocol set operation, i.e., interaction 2a above, containing all of the columns indicated by its column requirements.) Otherwise, the conceptual row is created, a `noError' response is returned, and the status column is immediately set to either `notInService' or `notReady', depending on whether it has sufficient information to (attempt to) make the conceptual row available for use by the managed device. If there is sufficient information available, then the status column is set to `notInService'; otherwise, if there is insufficient information, then the status column is set to `notReady'. Regardless, we proceed to interaction 3. Interaction 3: Initializing non-defaulted Objects The management station must now determine the column requirements. It issues a management protocol get operation to examine all columns in the created conceptual row. In the response, for each column, there are three possible outcomes: - a value is returned, indicating that the agent implements the object-type associated with this column and had sufficient information to provide a value. For those columns to which the agent provides read-create access (and for which the agent allows their values to be changed after their creation), a value return tells the management station that it may issue additional management protocol set operations, if it desires, in order to change the value associated with this column. - the exception `noSuchInstance' is returned, indicating that the agent implements the object-type associated with this column, and that this column in at least one conceptual row would be accessible in the MIB view used by the retrieval were it to exist. However, the agent does not have sufficient information to provide a value, and until a value is provided, the conceptual row may not be made available for use by the managed device. For those columns to which the agent provides read-create access, the `noSuchInstance' exception tells the management station that it must issue additional management protocol set operations, in order to provide a value associated with this column. - the exception `noSuchObject' is returned, indicating that the agent does not implement the object-type associated with this column or that there is no conceptual row for which this column would be accessible in the MIB view used by the retrieval. As such, the management station can not issue any management protocol set operations to create an instance of this column. If the value associated with the status column is `notReady', then the management station must first deal with all `noSuchInstance' columns, if any. Having done so, the value of the status column becomes `notInService', and we proceed to interaction 4. Interaction 4: Making the Conceptual Row Available Once the management station is satisfied with the values associated with the columns of the conceptual row, it issues a management protocol set operation to set the status column to `active'. If the agent has sufficient information to make the conceptual row available for use by the managed device, the management protocol set operation succeeds (a `noError' response is returned). Otherwise, the management protocol set operation fails with an error of `inconsistentValue'. NOTE WELL A conceptual row having a status column with value `notInService' or `notReady' is unavailable to the managed device. As such, it is possible for the managed device to create its own instances during the time between the management protocol set operation which sets the status column to `createAndWait' and the management protocol set operation which sets the status column to `active'. In this case, when the management protocol set operation is issued to set the status column to `active', the values held in the agent supersede those used by the managed device. If the management station is prevented from setting the status column to `active' (e.g., due to management station or network failure) the conceptual row will be left in the `notInService' or `notReady' state, consuming resources indefinitely. The agent must detect conceptual rows that have been in either state for an abnormally long period of time and remove them. It is the responsibility of the DESCRIPTION clause of the status column to indicate what an abnormally long period of time would be. This period of time should be long enough to allow for human response time (including `think time') between the creation of the conceptual row and the setting of the status to `active'. In the absence of such information in the DESCRIPTION clause, it is suggested that this period be approximately 5 minutes in length. This removal action applies not only to newly-created rows, but also to previously active rows which are set to, and left in, the notInService state for a prolonged period exceeding that which is considered normal for such a conceptual row. Conceptual Row Suspension When a conceptual row is `active', the management station may issue a management protocol set operation which sets the instance of the status column to `notInService'. If the agent is unwilling to do so, the set operation fails with an error of `wrongValue' or `inconsistentValue'. Otherwise, the conceptual row is taken out of service, and a `noError' response is returned. It is the responsibility of the DESCRIPTION clause of the status column to indicate under what circumstances the status column should be taken out of service (e.g., in order for the value of some other column of the same conceptual row to be modified). Conceptual Row Deletion For deletion of conceptual rows, a management protocol set operation is issued which sets the instance of the status column to `destroy'. This request may be made regardless of the current value of the status column (e.g., it is possible to delete conceptual rows which are either `notReady', `notInService' or `active'.) If the operation succeeds, then all instances associated with the conceptual row are immediately removed. · Integer32

The status of this conceptual row.