The MIB module is defined to configure the Announcements feature on the Media Gateway Card.
The Media Gateway Card will have the capability to play pre-recorded local announcements in switched VoIP solutions only. Under the control of a call agent, announcements can be played in either direction over existing connections (calls) or towards the Time Division Multiplexed (TDM) network on a TDM endpoint that is terminated on the the Media Gateway Card.
A large number of different announcements may be cached on the Media Gateway Card for immediate play out. A persistent announcement store, called the Announcement file server, will exist in the packet network and hold all the announcements in the network. Announcements will be downloaded on demand as announcement files from the configured announcement store. Downloaded announcement files will be stored on the Media Gateway Card as either 'permanent' or 'dynamic' announcement files. Permanent files on the Media Gateway Card are exempt from being refreshed, replaced, or removed without explicit provisioning actions. Dynamic announcement files will not persist across resets. Permanent announcement files will be reloaded, if possible, following a reset. Dynamic announcement files are automatically 'aged'. 'Aged' files are re-fetched from the Announcement file server. Dynamic Announcement files can be replaced on the Media Gateway Card if the Announcement memory on the card is full and additional Announcement files are to be downloaded. The file(s) to be replaced will be determined according to some Least Recently Used(LRU) algorithm.
Announcements can be played over established connections and unconnected TDM endpoints in any encoding supported by the Media Gateway Card in its current configuration. Announcement files must be encoded in G.729a to be played on G.729ab connections or, if G.729ab has been chosen as the preferred codec, unconnected endpoints.
The Announcement file server will reside on an IP network reachable from the Media Gateway Card using TFTP. The user will configure the Announcement file server node name on the the Media Gateway Card. The Announcement file server will have a 'main' file directory for Announcements. If the Announcement prefix path is configured to begin with a '/' then the directory is absolute. If the prefix path is configured to begin without a '/' then it will be relative to the default TFTP server directory. If no prefix path is configured then the Announcement 'main' directory and the TFTP default directory will be the same. The user must configure subdirectories within the main Announcement directory for each encoding that Announcements may be played in. These subdirectories must be of the following names: 'g711u', 'g711a', 'g726_40k', 'g726_32k', 'g726_24k', 'g726_16k', 'g729_a', 'g7231_high_rate', 'g7231_a_high_rate', 'g7231_low_rate', 'g7231_a_low_rate'.
The Media Gateway Card maintains an Announcement cache in resident memory. The cache is populated on demand with dynamic files or provisioned with permanent files. That is to say that when an Announcement is requested to be played it will first be retrieved from the Announcement file server and placed in the on-board Announcement cache. Subsequent requests for the same Announcement will not require retrieval of the Announcement file from the Announcement file server. Note that an Announcement in one encoding is a different file than the same Announcement in a different encoding.
The 'Announcement aging' policy is provisionable for dynamic files. Once a dynamic Announcement has 'aged' in the on-board cache it will be 'refreshed' by being retrieved again from the Announcement file server. The age time determines the maximum time before an updated Announcement file is automatically propagated to the card. Shorter age times will result in more frequent file server access. Changing the 'age' time does not affect the age times of dynamic Announcement files currently loaded. However, once these files are refreshed, they will then use the new 'age' time.
Announcements may also be provisioned as 'permanent'. A permanent Announcement will be fetched from the Announcement file server and 'frozen' in the Media Gateway Card Announcement cache. Permanent Announcements will be excluded from aging (and being automatically refreshed) and excluded from being replaced if the Announcement cache becomes full. Permanent Announcements can only be removed from the cache explicitly by user through command line interface or through a Network Manager. If the Media Gateway Card is reset, permanent Announcements will be re-fetched from the Announcement file server as soon as the card becomes active. The Announcement encoding must be specified when provisioning permanent Announcements.
This object records the maximum size of the Announcement table.
This number consists of the maximum number of Announcement file names that may be kept on the Media Gateway Card.
cwAnnFileServerName
1.3.6.1.4.1.351.150.25.1.1.1.2
DisplayStringRepresents textual information taken from the NVT ASCII
character set, as defined in pages 4, 10-11 of RFC 854.
To summarize RFC 854, the NVT ASCII repertoire specifies:
- the use of character codes 0-127 (decimal)
- the graphics characters (32-126) are interpreted as US ASCII
- NUL, LF, CR, BEL, BS, HT, VT and FF have the special meanings specified in RFC 854
- the other 25 codes have no standard interpretation
- the sequence 'CR LF' means newline
- the sequence 'CR NUL' means carriage-return
- an 'LF' not preceded by a 'CR' means moving to the same column on the next line.
- the sequence 'CR x' for any x other than LF or NUL is illegal. (Note that this also means that a string may end with either 'CR LF' or 'CR NUL', but not with CR.)
Any object defined using this syntax may not exceed 255 characters in length. SIZE (0..255) · OCTET STRING · hint 255a
This object records the name of the Announcement file server.
The individual characters in this name may be alphanumeric characters, forward slashes, backward slashes, periods, dashes, and underscores, but no embedded spaces. Also, the last character of the name must not be a dash or a forward slash.
The default value for this MIB object is a 'null'. If the Announcement file server name is not configured, Announcements cannot be downloaded.
The 'null' value of this field is a single space character, which may be set to this value by setting this MIB object to the single character space string (' '). Alternatively, for computing systems that cannot handle single character space strings, the single character ('_') underscore string may be used as an alternative 'null' value, which would then be converted internally to the single character space string.
Before the Announcement file server name may be successfully configured, the name must first be added to the list of domain names (mgDomainName) contained in the mgDomainNameTable(defined in CISCO-WAN-MG-MIB MIB). If the domain is configured for internal resolution, then the file server name must be asssigned an IP address to be put in the mgcResolutionTable(defined in CISCO-WAN-MG-MIB MIB).
cwAnnAgeTime
1.3.6.1.4.1.351.150.25.1.1.1.3
Integer32 (0..2147483647) · minutes
This object records the time in minutes for a dynamic Announcement file in the cache to age.
The Age time is the configurable number of minutes before a dynamic Announcement file in the Media Gateway Card Announcement cache will be invalidated and refreshed from the Announcement file server.
An Announcement file starts 'aging' as soon as it is brought into the cache from the file server.
Zero (0) time specifies that the age time is infinite, so that no aging will occur. But, unlike a permanent file, a file with aging of 0 may be replaced.
cwAnnPreferenceCodec
1.3.6.1.4.1.351.150.25.1.1.1.4
AnnCodecType1 = g711u2 = g711a3 = g726r320004 = g729a5 = g729ab7 = g726r160008 = g726r240009 = g726r4000011 = g723h12 = g723ah13 = g723l14 = g723alThis textual convention describes the Codec Type. The Announcement MIBs has two separate but identical objects which have the same structure for codec type, the scalar control group and the cwAnnounceTable.
Ref : ITU-T Series G: G.711 for 'g711u' and 'g711a'. Ref : ITU-T Series G: G.726 for 'g726r32000', 'g726r16000', 'g726r24000', 'g726r40000'. Ref : ITU-T Series G: G.729 for 'g729a' and 'g729ab'. Ref : ITU-T Series G: G.723.1 for 'g723h', 'g723ah', 'g723l', 'g723al'. · Integer32
This object records the codec to be used for playing Announcements on an unconnected TDM endpoint.
The default will be 'g711u' for a T1 Media Gateway Card, or will be 'g711a' for an E1 Media Gateway Card.
cwAnnPrefixPath
1.3.6.1.4.1.351.150.25.1.1.1.5
DisplayStringRepresents textual information taken from the NVT ASCII
character set, as defined in pages 4, 10-11 of RFC 854.
To summarize RFC 854, the NVT ASCII repertoire specifies:
- the use of character codes 0-127 (decimal)
- the graphics characters (32-126) are interpreted as US ASCII
- NUL, LF, CR, BEL, BS, HT, VT and FF have the special meanings specified in RFC 854
- the other 25 codes have no standard interpretation
- the sequence 'CR LF' means newline
- the sequence 'CR NUL' means carriage-return
- an 'LF' not preceded by a 'CR' means moving to the same column on the next line.
- the sequence 'CR x' for any x other than LF or NUL is illegal. (Note that this also means that a string may end with either 'CR LF' or 'CR NUL', but not with CR.)
Any object defined using this syntax may not exceed 255 characters in length. SIZE (0..255) · OCTET STRING · hint 255a
This object records the directory path under the default TFTP directory in the Announcement File server for announcement files.
The purpose of this MIB object is to specify the 'main' directory for Announcements if it is to be different than the default TFTP directory.
The individual characters in this name may be alphanumeric characters, forward slashes, backward slashes, periods, dashes, and underscores, but no embedded spaces. Also, the last character of the name must not be a dash or a forward slash.
If this MIB object is a 'null' value it will not cause any directory path string to be inserted with the cwAnnFileName MIB object.
The 'null' value of this field is a single space character, which may be set to this value by setting this MIB object to the single character space string (' '), or alternatively, for computing systems that cannot handle single character space strings, to the single character ('_') underscore string, which will then be converted internally to the single character space string.
cwAnnReqTimeout
1.3.6.1.4.1.351.150.25.1.1.1.6
Integer32 (0..2147483647) · seconds
This object records the time for a dynamic play Announcement request to be serviced.
If the Announcement subsystem cannot start playing the Announcement within cwAnnReqTimeout seconds since the request was received, the play request will be aborted.
Zero (0) time specifies that the timeout time is infinite, so that no timeout will occur.
Table details
cwAnnounceTable
1.3.6.1.4.1.351.150.25.1.1.2.1
Index: cwAnnounceNumber
This table contains configuration information about different permanent Announcements that are stored on the Media Gateway Card.
This table may contain up to the maximum number of permanent Announcement file names which is given by the value of cwAnnMaximumSize.
This attribute specifies the status of this entry regarding to the permanent Announcement file name in cwAnnFileName MIB object:
'loaded(1)': successfully downloaded permanent file.
'loading(2)': in process of downloading a permanent file.
'invalidFile(3)': file on File server is too large or corrupted.
'loadFailed(4)': timeout when trying to download a
permanent file.
When this entry is created with a valid permanent Announcement file name in the cwAnnFileName MIB object, this permanent status is set to 'loading(3)' while background activities attempt to download the permanent file from the Announcement FTP server. If this attempt is successful, the permanent status is set to 'loaded(3)', but if this process fails the permanent status is set to one either 'invalidFile(3)', or 'loadFailed(4)'.
Once an entry is loaded, if a subsequent card reset occurs the Media Gateway Card will attempt to restore all of the configuration information by doing its normal download of the latest MIB data base from the PXM (Processor Switch Module) hard disk, set all 'loaded (2)' MIB objects to 'loading (3)', and then do an background process to retrieve all of the Announcement files from the Announcement file server, since this information is not contained in the PXM. If this retrieval of the Announcement files succeeds then this MIB object will be set back to 'loaded (2)'. If this file retrieval does not succeed, then this MIB object will be set to one of: 'invalidFile(3)', or 'loadFailed(4)'.
cwAnnFileName
1.3.6.1.4.1.351.150.25.1.1.2.1.1.3
DisplayStringRepresents textual information taken from the NVT ASCII
character set, as defined in pages 4, 10-11 of RFC 854.
To summarize RFC 854, the NVT ASCII repertoire specifies:
- the use of character codes 0-127 (decimal)
- the graphics characters (32-126) are interpreted as US ASCII
- NUL, LF, CR, BEL, BS, HT, VT and FF have the special meanings specified in RFC 854
- the other 25 codes have no standard interpretation
- the sequence 'CR LF' means newline
- the sequence 'CR NUL' means carriage-return
- an 'LF' not preceded by a 'CR' means moving to the same column on the next line.
- the sequence 'CR x' for any x other than LF or NUL is illegal. (Note that this also means that a string may end with either 'CR LF' or 'CR NUL', but not with CR.)
Any object defined using this syntax may not exceed 255 characters in length. SIZE (0..255) · OCTET STRING · hint 255a
This is the name of a valid Announcement file which has been stored in the Announcement table as a permanent Announcement File name. This file name may include path or subdirectory information.
The individual characters in this name may be alphanumeric characters, forward slashes, backward slashes, periods, dashes, and underscores, but no embedded spaces. Also, the last character of the name must not be a dash or a forward slash.
However, single underscore character ('_') is considered a NULL string and should not consist cwAnnFileName name.
cwAnnFileCodec
1.3.6.1.4.1.351.150.25.1.1.2.1.1.4
AnnCodecType1 = g711u2 = g711a3 = g726r320004 = g729a5 = g729ab7 = g726r160008 = g726r240009 = g726r4000011 = g723h12 = g723ah13 = g723l14 = g723alThis textual convention describes the Codec Type. The Announcement MIBs has two separate but identical objects which have the same structure for codec type, the scalar control group and the cwAnnounceTable.
Ref : ITU-T Series G: G.711 for 'g711u' and 'g711a'. Ref : ITU-T Series G: G.726 for 'g726r32000', 'g726r16000', 'g726r24000', 'g726r40000'. Ref : ITU-T Series G: G.729 for 'g729a' and 'g729ab'. Ref : ITU-T Series G: G.723.1 for 'g723h', 'g723ah', 'g723l', 'g723al'. · Integer32
This object records the codec associated with a specific Announcdement file.
The default will be the value specified in the cwAnnPreferenceCodec MIB object above.
cwAnnRowStatus
1.3.6.1.4.1.351.150.25.1.1.2.1.1.5
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
Once a row is created, modification is not allowed on the row.
cwAnnFileName MIB object is the mandatory parameter for creating an entry in this table.
To delete an Announcement file entry, the RowStaus will be set to 'destroy'.