📄 rfc2670.txt
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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.
St. Johns Standard [Page 7]
RFC 2670 DOCSIS RF Interface MIB August 1999
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.
St. Johns Standard [Page 8]
RFC 2670 DOCSIS RF Interface MIB August 1999
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.
St. Johns Standard [Page 9]
RFC 2670 DOCSIS RF Interface MIB August 1999
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.
St. Johns Standard [Page 10]
RFC 2670 DOCSIS RF Interface MIB August 1999
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.
St. Johns Standard [Page 11]
RFC 2670 DOCSIS RF Interface MIB August 1999
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.
St. Johns Standard [Page 12]
RFC 2670 DOCSIS RF Interface MIB August 1999
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.
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