RFC 2670
Radio Frequency (RF) Interface Management Information Base for MCNS/DOCSIS compliant RF interfaces
Network Working Group M. St. Johns, Ed. Request for Comments: 2670 @Home Network Category: Proposed Standard August 1999 Radio Frequency (RF) Interface Management Information Base for MCNS/DOCSIS compliant RF interfaces Status of this Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (1999). All Rights Reserved.Abstract
This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. In particular, it defines a basic set of managed objects for SNMP- based management of MCNS/DOCSIS compliant Radio Frequency (RF) interfaces. This memo specifies a MIB module in a manner that is compliant to the SNMP SMIv2 [5][6][7]. The set of objects are consistent with the SNMP framework and existing SNMP standards. This memo is a product of the IPCDN working group within the Internet Engineering Task Force. Comments are solicited and should be addressed to the working group's mailing list at ipcdn@terayon.com and/or the author.Table of Contents
1 The SNMP Management Framework ................................... 3 2 Glossary ........................................................ 4 2.1 CATV .......................................................... 4 2.2 Channel ....................................................... 4 2.3 CM ............................................................ 4 2.4 CMTS .......................................................... 4 2.5 Codeword ...................................................... 4 2.6 Data Packet ................................................... 4
2.7 dBmV .......................................................... 4 2.8 DOCSIS ........................................................ 5 2.9 Downstream .................................................... 5 2.10 Head-end ..................................................... 5 2.11 MAC Packet ................................................... 5 2.12 MCNS ......................................................... 5 2.13 Mini-slot .................................................... 5 2.14 QPSK ......................................................... 5 2.15 QAM .......................................................... 5 2.16 RF ........................................................... 5 2.17 Symbol-times ................................................. 5 2.18 Upstream ..................................................... 6 3 Overview ........................................................ 6 3.1 Structure of the MIB .......................................... 6 3.1.1 docsIfBaseObjects ........................................... 6 3.1.2 docsIfCmObjects ............................................. 7 3.1.3 docsIfCmtsObjects ........................................... 7 3.2 Relationship to the Interfaces MIB ............................ 7 3.2.1 Layering Model .............................................. 7 3.2.2 Virtual Circuits ............................................ 8 3.2.3 ifTestTable ................................................. 9 3.2.4 ifRcvAddressTable ........................................... 9 3.2.5 ifEntry ..................................................... 9 3.2.5.1 ifEntry for Downstream interfaces ......................... 9 3.2.5.1.1 ifEntry for Downstream interfaces in Cable Modem Termination Systems .......................................... 9 3.2.5.1.2 ifEntry for Downstream interfaces in Cable Modems ...... 11 3.2.5.2 ifEntry for Upstream interfaces .......................... 12 3.2.5.2.1 ifEntry for Upstream interfaces in Cable Modem Termination Systems ......................................... 12 3.2.5.2.2 ifEntry for Upstream interfaces in Cable Modems ........ 14 3.2.5.3 ifEntry for the MAC Layer ................................ 15 4 Definitions .................................................... 18 5 Acknowledgments ................................................ 69 6 References ..................................................... 69 7 Security Considerations ........................................ 70 8 Intellectual Property .......................................... 71 9 Author's Address ............................................... 71 10 Full Copyright Statement ...................................... 72
1. The SNMP Management Framework
The SNMP Management Framework presently consists of five major components: o An overall architecture, described in RFC 2571 [1]. o Mechanisms for describing and naming objects and events for the purpose of management. The first version of this Structure of Management Information (SMI) is called SMIv1 and described in STD 16, RFC 1155 [2], STD 16, RFC 1212 [3] and RFC 1215 [4]. The second version, called SMIv2, is described in STD 58, RFC 2578 [5], STD 58, RFC 2579 [6] and STD 58, RFC 2580 [7]. o Message protocols for transferring management information. The first version of the SNMP message protocol is called SNMPv1 and described in RFC 1157 [8]. A second version of the SNMP message protocol, which is not an Internet standards track protocol, is called SNMPv2c and described in RFC 1901 [9] and RFC 1906 [10]. The third version of the message protocol is called SNMPv3 and described in RFC 1906 [10], RFC 2572 [11] and RFC 2574 [12]. o Protocol operations for accessing management information. The first set of protocol operations and associated PDU formats is described in STD 15, RFC 1157 [8]. A second set of protocol operations and associated PDU formats is described in RFC 1905 [13]. o A set of fundamental applications described in RFC 2573 [14] and the view-based access control mechanism described in RFC 2575 [15]. Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. Objects in the MIB are defined using the mechanisms defined in the SMI. This memo specifies a MIB module that is compliant to the SMIv2. A MIB conforming to the SMIv1 can be produced through the appropriate translations. The resulting translated MIB MUST be semantically equivalent, except where objects or events are omitted because no translation is possible (use of Counter64). Some machine readable information in SMIv2 will be converted into textual descriptions in SMIv1 during the translation process. However, this loss of machine readable information is not considered to change the semantics of the MIB.
2. Glossary
The terms in this document are derived either from normal cable system usage, or from the documents associated with the Data Over Cable Service Interface Specification process.2.1. CATV
Originally "Community Antenna Television", now used to refer to any cable or hybrid fiber and cable system used to deliver video signals to a community.2.2. Channel
A specific frequency allocation with an RF medium, specified by channel width in Hertz (cycles per second) and by center frequency. Within the US Cable Systems, upstream channels are generally allocated from the 5-42MHz range while down stream channels are generally allocated from the 50-750MHz range depending on the capabilities of the given system. The typical broadcast channel width in the US is 6MHz. Upstream channel widths for DOCSIS vary.2.3. CM Cable Modem.
A CM acts as a "slave" station in a DOCSIS compliant cable data system.2.4. CMTS Cable Modem Termination System.
A generic term covering a cable bridge or cable router in a head-end. A CMTS acts as the master station in a DOCSIS compliant cable data system. It is the only station that transmits downstream, and it controls the scheduling of upstream transmissions by its associated CMs.2.5. Codeword
See [16]. A characteristic of the Foward Error Correction scheme used above the RF media layer.2.6. Data Packet
The payload portion of the MAC Packet.2.7. dBmV
Decibel relative to one milli-volt. A measure of RF power.
2.8. DOCSIS
"Data Over Cable Interface Specification". A term referring to the ITU-T J.112 Annex B standard for cable modem systems [20].2.9. Downstream
The direction from the head-end towards the subscriber.2.10. Head-end
The origination point in most cable systems of the subscriber video signals.2.11. MAC Packet
A DOCSIS PDU.2.12. MCNS
"Multimedia Cable Network System". Generally replaced in usage by DOCSIS.2.13. Mini-slot
See [16]. In general, an interval of time which is allocated by the CMTS to a given CM for that CM to transmit in an upstream direction.2.14. QPSK Quadrature Phase Shift Keying.
A particular modulation scheme on an RF medium. See [19].2.15. QAM Quadrature Amplitude Modulation.
A particular modulation scheme on on RF medium. Usually expressed with a number indicating the size of the modulation constellation (e.g. 16 QAM). See [19], or any other book on digital communications over RF for a complete explanation of this.2.16. RF
Radio Frequency.2.17. Symbol-times
See [16]. A characteristic of the RF modulation scheme.
2.18. Upstream
The direction from the subscriber towards the head-end.3. Overview
This MIB provides a set of objects required for the management of MCNS/DOCSIS compliant Cable Modem (CM) and Cable Modem Termination System (CMTS) RF interfaces. The specification is derived in part from the parameters and protocols described in DOCSIS Radio Frequency Interface Specification [16].3.1. Structure of the MIB
This MIB is structured as three groups: o Management information pertinent to both Cable Modems (CM) and Cable Modem Termination Systems (CMTS) (docsIfBaseObjects). o Management information pertinent to Cable Modems only (docsIfCmObjects). o Management information pertinent to Cable Modem Termination Systems only (docsIfCmtsObjects). Tables within each of these groups group objects functionally - e.g. Quality of Service, Channel characteristics, MAC layer management, etc. Rows created automatically (e.g. by the device according to the hardware configuration) may and generally will have a mixture of configuration and status objects within them. Rows that are meant to be created by the management station are generally restricted to configuration (read-create) objects.3.1.1. docsIfBaseObjects
docsIfDownstreamChannelTable - This table describes the active downstream channels for a CMTS and the received downstream channel for a CM. docsIfUpstreamChannelTable - This table describes the active upstream channels for a a CMTS and the current upstream transmission channel for a CM. docsIfQosProfileTable - This table describes the valid Quality of Service service profiles for the cable data system. docsIfSignalQualityTable - This table is used to monitor RF signal quality characteristics of received signals.
3.1.2. docsIfCmObjects
docsIfCmMacTable - This table is used to monitor the DOCSIS MAC interface and can be considered an extension to the ifEntry. docsIfCmServiceTable - This table describes the upstream service queues available at this CM. There is a comparable table at the CMTS, docsIfCmtsServiceEntry, which describes the service queues from the point of view of the CMTS.3.1.3. docsIfCmtsObjects
docsIfCmtsStatusTable - This table provides a set of aggregated counters which roll-up values and events that occur on the underlying sub-interfaces. docsIfCmtsCmStatusTable - This table is used to hold information about known (e.g. registered) cable modems on the system serviced by this CMTS. docsIfCmtsServiceEntry - This table provides access to the information related to upstream service queues. docsIfCmtsModulationTable - This table allows control over the modulation profiles for RF channels associated with this CMTS. docsIfCmtsMacToCmTable - This table allows fast access into the docsIfCmtsCmTable via a MAC address (of the CM) interface.3.2. Relationship to the Interfaces MIB
This section clarifies the relationship of this MIB to the Interfaces MIB [17]. Several areas of correlation are addressed in the following subsections. The implementor is referred to the Interfaces MIB document in order to understand the general intent of these areas.3.2.1. Layering Model
An instance of ifEntry exists for each RF Downstream interface, for each RF Upstream interface, and for each RF MAC layer. The ifStackTable [17] MUST be implemented to identify relationships among sub-interfaces.
The following example illustrates a MAC interface with one downstream
and two upstream channels.
| <== to network layer
+-------------+--------------+
| RF MAC |
+----+---------+-----------+-+
| | |
+---------+---+ +---+-------+ +-+---------+
| Downstream1 | | Upstream1 | | Upstream2 |
+-------------+ +-----------+ +-----------+
As can be seen from this example, the RF MAC interface is layered on
top of the downstream and upstream interfaces.
In this example, the assignment of index values could be as follows:
ifIndex ifType Description
1 docsCableMaclayer(127) CATV MAC Layer
2 docsCableDownstream(128) CATV Downstream interface
3 docsCableUpstream(129) CATV Upstream interface
4 docsCableUpstream(129) CATV Upstream interface
The corresponding ifStack entries would then be:
| IfStackHigherLayer | ifStackLowerLayer |
| 0 | 1 |
| 1 | 2 |
| 1 | 3 |
| 1 | 4 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
The same interface model can also be used in Telephony or Telco
Return systems. A pure Telco Return system (Cable Modem as well as
Cable Modem Termination System) would not have upstream, but only
downstream cable channels. Systems supporting both Telco Return and
cable upstream channels can use the above model without modification.
Telco Return Upstream channel(s) are handled by the appropriate MIBs,
such as PPP or Modem MIBs.
3.2.2. Virtual Circuits
This medium does not support virtual circuits and this area is not
applicable to this MIB.
3.2.3. ifTestTable
The ifTestTable is not supported by this MIB.3.2.4. ifRcvAddressTable
The ifRcvAddressTable is not supported by this MIB.3.2.5. ifEntry
This section documents only the differences from the requirements specified in the Interfaces MIB. See that MIB for columns omitted from the descriptions below.3.2.5.1. ifEntry for Downstream interfaces
The ifEntry for Downstream interfaces supports the ifGeneralInformationGroup and the ifPacketGroup of the Interfaces MIB. This is an output only interface at the CMTS and all input status counters - ifIn* - will return zero. This is an input only interface at the CM and all output status counters - ifOut* - will return zero.3.2.5.1.1. ifEntry for Downstream interfaces in Cable Modem Termination Systems
ifTable Comments ============== =========================================== ifIndex Each RF Cable Downstream interface is represented by an ifEntry. ifType The IANA value of docsCableDownstream(128). ifSpeed Return the speed of this downstream channel. The returned value the raw bandwidth in bits/s of this interface. This is the symbol rate multiplied with the number of bits per symbol. ifPhysAddress Return an empty string. ifAdminStatus The administrative status of this interface. ifOperStatus The current operational status of this interface. ifMtu The size of the largest frame which can be sent on this interface, specified in octets. The value includes the length of the MAC header.
ifInOctets Return zero.
ifInUcastPkts Return zero.
ifInMulticastPkts Return zero.
ifInBroadcastPkts Return zero.
ifInDiscards Return zero.
ifInErrors Return zero.
ifInUnknownProtos Return zero.
ifOutOctets The total number of octets transmitted on this
interface. This includes MAC packets as well as
data packets, and includes the length of the MAC
header.
ifOutUcastPkts The number of Unicast packets transmitted on this
interface. This includes MAC packets as well as
data packets.
ifOutMulticastPkts
Return the number of Multicast packets transmitted
on this interface.
This includes MAC packets as well as data packets.
ifOutBroadcastPkts
Return the number of broadcast packets transmitted
on this interface.
This includes MAC packets as well as data packets.
ifOutDiscards The total number of outbound packets which
were discarded. Possible reasons are:
buffer shortage.
ifOutErrors The number of packets which could not be
transmitted due to errors.
ifPromiscuousMode Return false.
3.2.5.1.2. ifEntry for Downstream interfaces in Cable Modems
ifTable Comments ============== =========================================== ifIndex Each RF Cable Downstream interface is represented by an ifEntry. ifType The IANA value of docsCableDownstream(128). ifSpeed Return the speed of this downstream channel. The returned value the raw bandwidth in bits/s of this interface. This is the symbol rate multiplied with the number of bits per symbol. ifPhysAddress Return an empty string. ifAdminStatus The administrative status of this interface. ifOperStatus The current operational status of this interface. ifMtu The size of the largest frame which can be received from this interface, specified in octets. The value includes the length of the MAC header. ifInOctets The total number of octets received on this interface. This includes data packets as well as MAC layer packets, and includes the length of the MAC header. ifInUcastPkts The number of Unicast packets received on this interface. This includes data packets as well as MAC layer packets. ifInMulticastPkts Return the number of Multicast packets received on this interface. This includes data packets as well as MAC layer packets. ifInBroadcastPkts Return the number of Broadcast packets received on this interface. This includes data packets as well as MAC layer packets. ifInDiscards The total number of received packets which have been discarded. The possible reasons are: buffer shortage. ifInErrors The number of inbound packets that contained errors preventing them from being deliverable to higher layers.
Possible reasons are: MAC FCS error.
ifInUnknownProtos The number of frames with an unknown packet type.
These are MAC frames with an unknown packet type.
ifOutOctets Return zero.
ifOutUcastPkts Return zero.
ifOutMulticastPkts
Return zero.
ifOutBroadcastPkts
Return zero.
ifOutDiscards Return zero.
ifOutErrors Return zero.
ifPromiscuousMode Refer to the Interfaces MIB.
3.2.5.2. ifEntry for Upstream interfaces
The ifEntry for Upstream interfaces supports the
ifGeneralInformationGroup and the ifPacketGroup of the Interfaces
MIB. This is an input only interface at the CMTS and all output
status counters - ifOut* - will return zero. This is an output only
interface at the CM and all input status counters - ifIn* - will
return zero.
3.2.5.2.1. ifEntry for Upstream interfaces in Cable Modem Termination
Systems
ifTable Comments
============== ===========================================
ifIndex Each RF Cable Upstream interface is represented
by an ifEntry.
ifType The IANA value of docsCableUpstream(129).
ifSpeed Return the speed of this upstream channel.
The returned value is the raw bandwidth
in bits/s of this interface, regarding the
highest speed modulation profile that is
defined. This is the symbol rate multiplied
with the number of bits per symbol for this
modulation profile.
ifPhysAddress Return an empty string.
ifAdminStatus The administrative status of this interface.
ifOperStatus The current operational status of this interface.
ifMtu The size of the largest frame which can be
received on this interface, specified in octets.
The value includes the length of the MAC header.
ifInOctets The total number of octets received on this
interface. This includes data packets as well as
MAC layer packets, and includes the length of the
MAC header.
ifInUcastPkts The number of Unicast packets received on this
interface. This includes data packets as well as
MAC layer packets.
ifInMulticastPkts Return the number of Multicast packets received
on this interface. This includes data packets as
well as MAC layer packets.
ifInBroadcastPkts Return the number of Broadcast packets received
on this interface. This includes data packets
as well as MAC layer packets.
ifInDiscards The total number of received packets which have
been discarded.
The possible reasons are: buffer shortage.
ifInErrors The number of inbound packets that contained
errors preventing them from being deliverable
to higher layers.
Possible reasons are: MAC FCS error.
ifInUnknownProtos The number of frames with an unknown packet type.
This are MAC frames with an unknown packet type.
ifOutOctets Return zero.
ifOutUcastPkts Return zero.
ifOutMulticastPkts
Return zero.
ifOutBroadcastPkts
Return zero.
ifOutDiscards Return zero. ifOutErrors Return zero.3.2.5.2.2. ifEntry for Upstream interfaces in Cable Modems
ifTable Comments ============== =========================================== ifIndex Each RF Cable Upstream interface is represented by an ifEntry. ifType The IANA value of docsCableUpstream(129). ifSpeed Return the speed of this upstream channel. The returned value is the raw bandwidth in bits/s of this interface, regarding the highest speed modulation profile that is defined. This is the symbol rate multiplied with the number of bits per symbol for this modulation profile. ifPhysAddress Return an empty string. ifAdminStatus The administrative status of this interface. ifOperStatus The current operational status of this interface. ifMtu The size of the largest frame which can be transmitted on this interface, specified in octets. The value includes the length of the MAC header. ifInOctets Return zero. ifInUcastPkts Return zero. ifInMulticastPkts Return zero. ifInBroadcastPkts Return zero. ifInDiscards Return zero. ifInErrors Return zero. ifInUnknownProtos Return zero.
ifOutOctets The total number of octets transmitted on this
interface. This includes MAC packets as well as
data packets, and includes the length of the MAC
header.
ifOutUcastPkts The number of Unicast packets transmitted on this
interface. This includes MAC packets as well as
data packets.
ifOutMulticastPkts
Return the number of Multicast packets transmitted
on this interface.
This includes MAC packets as well as data packets.
ifOutBroadcastPkts
Return the number of broadcast packets transmitted
on this interface.
This includes MAC packets as well as data packets.
ifOutDiscards The total number of outbound packets which
were discarded. Possible reasons are:
buffer shortage.
ifOutErrors The number of packets which could not be
transmitted due to errors.
ifPromiscuousMode Return false.
3.2.5.3. ifEntry for the MAC Layer
The ifEntry for the MAC Layer supports the ifGeneralInformationGroup
and the ifPacketGroup of the Interfaces MIB. This interface provides
an aggregate view of status for the lower level Downstream and
Upstream interfaces.
ifTable Comments
============== ===========================================
ifIndex Each RF Cable MAC layer entity is represented
by an ifEntry.
ifType The IANA value of docsCableMaclayer(127).
ifSpeed Return zero.
ifPhysAddress Return the physical address of this interface.
ifAdminStatus The administrative status of this interface.
ifOperStatus The current operational status of the MAC
layer interface.
ifHighSpeed Return zero.
ifMtu Return 1500.
ifInOctets The total number of data octets received on this
interface, targeted for upper protocol layers.
ifInUcastPkts The number of Unicast packets received on this
interface, targeted for upper protocol layers.
ifInMulticastPkts Return the number of Multicast packets received
on this interface, targeted for upper protocol
layers.
ifInBroadcastPkts Return the number of Broadcast packets received
on this interface, targeted for upper protocol
layers.
ifInDiscards The total number of received packets which have
been discarded.
The possible reasons are: buffer shortage.
ifInErrors The number of inbound packets that contained
errors preventing them from being deliverable
to higher layers.
Possible reasons are: data packet FCS error,
invalid MAC header.
ifInUnknownProtos The number of frames with an unknown packet type.
This is the number of data packets targeted for
upper protocol layers with an unknown packet type.
ifOutOctets The total number of octets, received from upper
protocol layers and transmitted on this interface.
ifOutUcastPkts The number of Unicast packets, received from upper
protocol layers and transmitted on this interface.
ifOutMulticastPkts
Return the number of Multicast packets received
from upper protocol layers and transmitted on this
interface.
ifOutBroadcastPkts
Return the number of broadcast packets received
from upper protocol layers and transmitted on this
interface.
ifOutDiscards The total number of outbound packets which
were discarded. Possible reasons are:
buffer shortage.
ifOutErrors The number of packets which could not be
transmitted due to errors.
ifPromiscuousMode Refer to the Interfaces MIB.
(next page on part 2)
