Definitions of Managed Object Extensions for Very High Speed Digital Subscriber Lines (VDSL) Using Multiple Carrier Modulation (MCM) Line Coding
Extracted elements (20)
The MIB is structured as an optional extension to RFC 3728 (VDSL-LINE-MIB) rather than a standalone MIB, separating line-code-independent (TC layer) objects from MCM-specific (PMD layer) objects to allow agents that do not support MCM to remain compliant.
For transmit and receive band entries, each entry must be internally consistent (Stop Tone > Start Tone) and externally consistent (no overlapping bands across entries indexed by the same profile); both checks occur during profile validation.
This MIB is an optional extension to VDSL-LINE-MIB (RFC 3728); an MCM-based VDSL agent does not have to implement this MIB to be compliant with RFC 3728. If implemented, the vdslMCMGroup is mandatory.
When vdslLineCoding is set to MCM, vdslLineConfProfileName is used as the index to each of the six vdslLineMCMConfProfile tables; if an entry references a non-MCM line, it has no effect on that line's operation.
All read-create objects defined in this MIB module SHOULD be stored persistently, including all band, PSD, and profile configuration objects.
Deployment of SNMP versions prior to SNMPv3 is NOT RECOMMENDED; instead SNMPv3 with cryptographic security SHOULD be deployed.
If the MCM VDSL Line Extension MIB is implemented, all objects in the vdslMCMGroup MUST be implemented.
Implementers are RECOMMENDED to consider the security features provided by the SNMPv3 framework, including full support for SNMPv3 cryptographic mechanisms for authentication and privacy.
The objects in this extension MIB MUST NOT be used for VDSL lines using Single Carrier Modulation (SCM) line coding.
VACM data relating to interface indices in this MIB SHOULD be stored persistently.
The vdslLineMCMConfProfileMaxTxPSDTable and vdslLineMCMConfProfileMaxRxPSDTable define maximum transmit and receive PSD mask descriptors per tone; each profile must have at most one entry per tone index.
The vdslLineMCMConfProfileTable contains additional configuration information for MCM VDSL lines; each entry represents a manager-defined profile used to configure a VDSL line, indexed by vdslLineConfProfileName.
The vdslLineMCMConfProfileTxBandTable and vdslLineMCMConfProfileRxBandTable each define transmit and receive band descriptors respectively, with each entry specifying a start tone index and stop tone index (range 1..4096).
The vdslLineMCMConfProfileTxPSDTable defines per-tone transmit Power Spectral Density mask descriptors; vdslLineMCMConfProfileTxPSDPSD is expressed in units of 0.5dBm/Hz with an offset of -140dBm/Hz.
vdslLineMCMConfProfileTxWindowLength specifies the transmit window length in samples (range 1..255) at the sampling rate corresponding to the negotiated value of N.
IANA assigned transmission value 229 to VDSL-LINE-EXT-MCM-MIB (OID { transmission 229 }).
Read access to physical band parameters may reveal information enabling malicious interference on one or all physical bands in use; GET and NOTIFY access should be controlled and values may warrant encryption in transit.
Read-create objects in this MIB (band configuration, PSD masks, window length) are sensitive; SET operations in non-secure environments without proper protection can negatively affect network operations, including enabling end-users to increase service levels or degrade other users.
VDSL layer connectivity from the remote (Vtur) end permits subscribers to manipulate the VDSL link and embedded operations channel; unfiltered fluctuations could generate sufficient notifications to overwhelm the management interface or element manager.
Profile row lifecycle is managed via RowStatus: a profile is activated by setting RowStatus to 'active' (triggering validation); columns cannot be modified while 'active'; the profile must be unreferenced from all associated lines before being set to 'destroy' or 'notInService'.