4. Relation to Other MIB Modules

4.1. Frame Relay DTE MIB

There is no required relation to the Frame Relay DTE MIB beyond the fact that rows in the frCircuitTable MAY be referenced. However, if frCircuitLogicalIfIndex is being used to represent the same information as a ciCircuitEntry with a value of ciCircuitFlow equal to both(3), the implementation MAY use the same ifIndex.

4.2. Frame Relay Service MIB

There is no explicit relation to the Frame Relay Service MIB beyond the fact that a rows in the frPVCEndptTable MAY be referenced.

4.3. ATM MIB

There is no explicit relation to the ATM MIB beyond the fact that rows in multiple tables may be referenced.

4.4. Interfaces Group MIB

4.4.1. Interfaces Table (ifTable, ifXtable)

The following specifies how the Interfaces Group defined in the IF-MIB will be used for the management of interfaces created by this MIB module.

Values of specific ifTable objects for circuit interfaces are as follows:

Object Name	Value of Object
ifIndex	Each entry in the circuit table is represented by an ifEntry. The value of ifIndex is defined by the agent such that it complies with any internal numbering scheme.
ifType	The value of ifType is specific to the type of circuit desired. For example, the value for frame relay virtual circuits is frDlciEndPt(193) and the value for ATM virtual circuits is atmVciEndPt(194). If the circuit is to be used in RMON, propVirtual(53) SHOULD NOT be used.
ifMtu	Set to the size in octets of the largest packet, frame or PDU supported on the circuit. If this is not known to the ifMtu object shall be set to zero. If the circuit is not modeled as a packet-oriented interface, this object SHOULD NOT be supported and result in noSuchInstance.
ifSpeed	The peak bandwidth in bits per second available for use. This will equal either the ifSpeed of the logical link if policing is not enforced or the maximum information rate otherwise. If neither is known, the ifSpeed object shall be set to zero.
ifPhysAddress	This will always be an octet string of zero length.
ifInOctets	The number of octets received by the network (ingress) for this circuit. This counter should count only octets included the header information and user data. If the device does not support statistics on the circuit, this object MUST NOT be supported and result in noSuchInstance.
ifInUcastPkts	The unerrored number of frames, packets or PDUs received by the network (ingress) for this circuit. If the device does not support statistics on the circuit, this object MUST NOT be supported and result in noSuchInstance.
ifInDiscards	The number of received frames, packets or PDUs for this circuit discarded due to ingress buffer congestion and traffic policing. If the device does not support statistics on the circuit, this object MUST NOT be supported and result in noSuchInstance.
ifInErrors	The number of received frames, packets or PDUs for this circuit that are discarded because of an error. If the device does not support statistics on the circuit, this object MUST NOT be supported and result in noSuchInstance.
ifOutOctets	The number of octets sent by the network (egress) for this circuit. This counter should count only octets included the header information and user data. If the device does not support statistics on the circuit, this object MUST NOT be supported and result in noSuchInstance.
ifOutUcastpkts	The number of unerrored frames, packets or PDUs sent by the network (egress) for this circuit. If the device does not support statistics on the circuit, this object MUST NOT be supported and result in noSuchInstance.
ifOutDiscards	The number of frames, packets or PDUs discarded in the egress direction for this circuit. Possible reasons are as follows: policing, congestion. If the device does not support statistics on the circuit, this object MUST NOT be supported and result in noSuchInstance.
ifOutErrors	The number of frames, packets or PDUs discarded for this circuit in the egress direction because of an error. If the device does not support statistics on the circuit, this object MUST NOT be supported and result in noSuchInstance.
ifInBroadcastPkts	If the device does not support statistics on the circuit, this object MUST NOT be supported and result in noSuchInstance.
ifOutBroadcastPkts	If the device does not support Broadcast packets on the circuit, this object should not be supported and result in noSuchInstance.
ifLinkUpDownTrapEnable	Set to false(2). Circuits often have a predefined notification mechanism. In such instances, the number of notification sent would be doubled if this were enabled.
ifPromiscuousMode	Set to false(2). If the circuit is not modeled as a packet-oriented interface, this object SHOULD NOT be supported and result in noSuchInstance.
ifConnectorPresent	Set to false(2).

All other values are supported as stated in the IF-MIB documentation.

4.4.2. Stack Table (ifStackTable)

This section describes by example how to use ifStackTable to represent the relationship between circuit and logical link interfaces.

Example 1: Circuits (C) on a frame relay logical link.

  +---+  +---+  +---+
  | C |  | C |  | C |
  +-+-+  +-+-+  +-+-+
    |      |      |
+---+------+------+---+
| Frame Relay Service |
+----------+----------+
           |
+----------+----------+
|   Physical Layer    |
+---------------------+

The assignment of the index values could for example be (for a V35 physical interface):

ifIndex	Description
1	frDlciEndPt (type 193)
2	frDlciEndPt (type 193)
3	frDlciEndPt (type 193)
4	frameRelayService (type 44)
5	v35 (type 33)

The ifStackTable is then used to show the relationships between each interface.

HigherLayer	LowerLayer
0	1
0	2
0	3
1	4
2	4
3	4
4	5
5	0

In the above example the frame relay logical link could just as easily be of type frameRelay(32) instead.

Example 2: Circuits (C) on a AAL5 logical link.

     +---+  +---+  +---+
     | C |  | C |  | C |
     +-+-+  +-+-+  +-+-+
       |      |      |
   +---+------+------+---+
   |      AAL5 Layer     |
   +----------+----------+
              |
   +----------+----------+
   |      ATM Layer      |
   +---------------------+
              |
   +----------+----------+
   |   Physical Layer    |
   +---------------------+

The assignment of the index values could for example be (for a DS3 physical interface):

ifIndex	Description
1	atmVciEndPt (type 194)
2	atmVciEndPt (type 194)
3	atmVciEndPt (type 194)
4	aal5 (type 49)
5	atm (type 37)
6	ds3 (type 30)

The ifStackTable is then used to show the relationships between each interface.

HigherLayer	LowerLayer
0	1
0	2
0	3
1	4
2	4
3	4
4	5
5	6
6	0

4.5. Other MIB Modules

There is no explicit relation to any other media specific MIB module beyond the fact that rows in multiple tables may be referenced.