PTOPO-MIB

All MIBs › PTOPO-MIB

Organization: IETF; PTOPOMIB Working Group

Last Updated: 2000-09-21

Category: Network Monitoring (RMON)

Description: Defines managed objects for physical topology discovery, identifying connections between network ports.

IPNetwork Monitor uses several OIDs from this MIB in network discovery and polling the applicable devices. Start monitoring PTOPO-MIB with a free 30-day trial of IPNetwork Monitor.

What Is PTOPO-MIB?

PTOPO-MIB (the Physical Topology MIB) is a vendor-neutral IETF standards-track module that defines managed objects for discovering and representing the physical connectivity between ports on network devices, similar in spirit to what later became LLDP-MIB. It exposes a connection table capturing local chassis/port identifiers and their discovered remote neighbor chassis and port, along with the discovery algorithm used. Rather than hardware health counters, its focus is topology/configuration data: it lets a management station build an accurate picture of which physical port on one device connects to which port on another, enabling detection of unexpected disconnections, rewiring, or topology changes. It builds on the general SNMP SMIv2 framework and is conceptually related to link-layer discovery mechanisms defined by other IETF and IEEE efforts. It's typically deployed on switches, routers, and hubs that support physical topology (Layer 2) discovery so NMS tools can auto-map network wiring. Engineers implementing or auditing this functionality typically reference the PTOPO-MIB RFC/standard documentation for the authoritative specification.

IPNetwork Monitor allows you to monitor SNMP objects defined in PTOPO-MIB. Use the built-in SNMP Monitoring Browser to explore available variables, view their current values and descriptions, and select the objects you want to monitor. You can then create SNMP monitors, configure thresholds, and receive alerts when monitored values change.

Supported Devices

vendor-neutral, standards-based MIB, not tied to a specific manufacturer
network switches, routers, and hubs supporting physical topology discovery

Monitoring Examples

A network management station would poll ptopoConnTable/ptopoConnEntry, indexed by ptopoConnLocalPort and ptopoConnIndex, to read ptopoConnRemoteChassis and ptopoConnRemotePort for each discovered neighbor. A sudden absence of a previously-seen entry, or a change in ptopoConnRemoteChassisType, reveals a cable pull, port shutdown, or unexpected rewiring event. ptopoConnTimeMark and ptopoConnDiscAlgorithm let the poller confirm how recently and by what method the neighbor relationship was learned.

What Can Be Monitored

discovered neighbor chassis
discovered neighbor port
local port-to-remote port mapping
topology discovery algorithm used
connection table discovery timestamp

Imported Objects

From ENTITY-MIB

PhysicalIndex

From IANA-ADDRESS-FAMILY-NUMBERS-MIB

AddressFamilyNumbers

From RMON2-MIB

TimeFilter

From SNMPv2-CONF

MODULE-COMPLIANCE
NOTIFICATION-GROUP
OBJECT-GROUP

From SNMPv2-SMI

Counter32
Integer32
MODULE-IDENTITY
NOTIFICATION-TYPE
OBJECT-TYPE
mib-2

From SNMPv2-TC

AutonomousType
RowStatus
TEXTUAL-CONVENTION
TimeStamp
TruthValue

How to Use in IPNetwork Monitor

Example using ptopoConnTabInserts OID:

Select a device implementing PTOPO-MIB as the target host to create a monitor — the SNMP service should be up and running on it. Click New Monitor, then check SNMP Custom on the Favorites tab, click Next, and confirm the host. On the next page, click Select... to open the built-in SNMP MIB Browser and type ptopoConnTabInserts into the Find box to locate it in the OID tree, then select it and click OK. The number of times an entry has been inserted into the ptopoConnTable. On the monitor's Main parameters page you can set the target's SNMP port (default 161), credentials, polling interval, and other settings — see the SNMP Monitor help for details. On the State conditions and Alerting tabs, configure when the monitor should change state and trigger an alert; since this is a Counter32-type OID, Value bounds is the most useful condition here — trigger an alert if the counter increases sharply between polls relative to its normal baseline (in table entries), since an unexpected spike often reflects a real change in traffic or activity. Click Finish to create the monitor; you can adjust any parameter later.

OIDs

OID symbolic	OID numeric	Type	Access	Description
ptopoMIB	1.3.6.1.2.1.79			The MIB module for physical topology information.
ptopoMIBObjects	1.3.6.1.2.1.79.1
ptopoData	1.3.6.1.2.1.79.1.1
ptopoConnTable	1.3.6.1.2.1.79.1.1.1		not-accessible	This table contains one or more rows per physical network connection known to this agent. The agent may wish to ensure that only one ptopoConnEntry is present for each local port, or it may choose to maintain multiple ptopoConnEntries for the same local port. Entries based on lower numbered identifier types are preferred over higher numbered identifier types, i.e., lower values of the ptopoConnRemoteChassisType and ptopoConnRemotePortType objects.
ptopoConnEntry	1.3.6.1.2.1.79.1.1.1.1		not-accessible	Information about a particular physical network connection. Entries may be created and deleted in this table, either manually or by the agent, if a physical topology discovery process is active.
TIM ptopoConnTimeMark	1.3.6.1.2.1.79.1.1.1.1.1	TimeFilter	not-accessible	A TimeFilter for this entry. See the TimeFilter textual convention in RFC 2021 to see how this works.
PHY ptopoConnLocalChassis	1.3.6.1.2.1.79.1.1.1.1.2	PhysicalIndex	not-accessible	The entPhysicalIndex value used to identify the chassis component associated with the local connection endpoint.
PHY ptopoConnLocalPort	1.3.6.1.2.1.79.1.1.1.1.3	PhysicalIndex	not-accessible	The entPhysicalIndex value used to identify the port component associated with the local connection endpoint.
I32 ptopoConnIndex	1.3.6.1.2.1.79.1.1.1.1.4	Integer32	not-accessible	This object represents an arbitrary local integer value used by this agent to identify a particular connection instance, unique only for the indicated local connection endpoint. A particular ptopoConnIndex value may be reused in the event an entry is aged out and later re-learned with the same (or different) remote chassis and port identifiers. An agent is encouraged to assign monotonically increasing index values to new entries, starting with one, after each reboot. It is considered unlikely that the ptopoConnIndex will wrap between reboots.
PTO ptopoConnRemoteChassisType	1.3.6.1.2.1.79.1.1.1.1.5	PtopoChassisIdType	read-create	The type of encoding used to identify the chassis associated with the remote connection endpoint. This object may not be modified if the associated ptopoConnRowStatus object has a value of active(1).
PTO ptopoConnRemoteChassis	1.3.6.1.2.1.79.1.1.1.1.6	PtopoChassisId	read-create	The string value used to identify the chassis component associated with the remote connection endpoint. This object may not be modified if the associated ptopoConnRowStatus object has a value of active(1).
PTO ptopoConnRemotePortType	1.3.6.1.2.1.79.1.1.1.1.7	PtopoPortIdType	read-create	The type of port identifier encoding used in the associated 'ptopoConnRemotePort' object. This object may not be modified if the associated ptopoConnRowStatus object has a value of active(1).
PTO ptopoConnRemotePort	1.3.6.1.2.1.79.1.1.1.1.8	PtopoPortId	read-create	The string value used to identify the port component associated with the remote connection endpoint. This object may not be modified if the associated ptopoConnRowStatus object has a value of active(1).
OID ptopoConnDiscAlgorithm	1.3.6.1.2.1.79.1.1.1.1.9	AutonomousType	read-only	An indication of the algorithm used to discover the information contained in this conceptual row. A value of ptopoDiscoveryLocal indicates this entry was configured by the local agent, without use of a discovery protocol. A value of { 0 0 } indicates this entry was created manually by an NMS via the associated RowStatus object.
ADR ptopoConnAgentNetAddrType	1.3.6.1.2.1.79.1.1.1.1.10	AddressFamilyNumbers	read-create	This network address type of the associated ptopoConnNetAddr object, unless that object contains a zero length string. In such a case, an NMS application should ignore any returned value for this object. This object may not be modified if the associated ptopoConnRowStatus object has a value of active(1).
PTO ptopoConnAgentNetAddr	1.3.6.1.2.1.79.1.1.1.1.11	PtopoGenAddr	read-create	This object identifies a network address which may be used to reach an SNMP agent entity containing information for the chassis and port components represented by the associated 'ptopoConnRemoteChassis' and 'ptopoConnRemotePort' objects. If no such address is known, then this object shall contain an empty string. This object may not be modified if the associated ptopoConnRowStatus object has a value of active(1).
PTO ptopoConnMultiMacSASeen	1.3.6.1.2.1.79.1.1.1.1.12	PtopoAddrSeenState	read-only	This object indicates if multiple unicast source MAC addresses have been detected by the agent from the remote connection endpoint, since the creation of this entry. If this entry has an associated ptopoConnRemoteChassisType and/or ptopoConnRemotePortType value other than 'portIdMacAddr(3)', then the value 'notUsed(1)' is returned. Otherwise, one of the following conditions must be true: If the agent has not yet detected any unicast source MAC addresses from the remote port, then the value 'unknown(2)' is returned. If the agent has detected exactly one unicast source MAC address from the remote port, then the value 'oneAddr(3)' is returned. If the agent has detected more than one unicast source MAC address from the remote port, then the value 'multiAddr(4)' is returned.
PTO ptopoConnMultiNetSASeen	1.3.6.1.2.1.79.1.1.1.1.13	PtopoAddrSeenState	read-only	This object indicates if multiple network layer source addresses have been detected by the agent from the remote connection endpoint, since the creation of this entry. If this entry has an associated ptopoConnRemoteChassisType or ptopoConnRemotePortType value other than 'portIdGenAddr(4)' then the value 'notUsed(1)' is returned. Otherwise, one of the following conditions must be true: If the agent has not yet detected any network source addresses of the appropriate type from the remote port, then the value 'unknown(2)' is returned. If the agent has detected exactly one network source address of the appropriate type from the remote port, then the value 'oneAddr(3)' is returned. If the agent has detected more than one network source address (of the same appropriate type) from the remote port, this the value 'multiAddr(4)' is returned.
T/F ptopoConnIsStatic	1.3.6.1.2.1.79.1.1.1.1.14	TruthValue	read-create	This object identifies static ptopoConnEntries. If this object has the value 'true(1)', then this entry is not subject to any age-out mechanisms implemented by the agent. If this object has the value 'false(2)', then this entry is subject to all age-out mechanisms implemented by the agent. This object may not be modified if the associated ptopoConnRowStatus object has a value of active(1).
TIM ptopoConnLastVerifyTime	1.3.6.1.2.1.79.1.1.1.1.15	TimeStamp	read-only	If the associated value of ptopoConnIsStatic is equal to 'false(2)', then this object contains the value of sysUpTime at the time the conceptual row was last verified by the agent, e.g., via reception of a topology protocol message, pertaining to the associated remote chassis and port. If the associated value of ptopoConnIsStatic is equal to 'true(1)', then this object shall contain the value of sysUpTime at the time this entry was last activated (i.e., ptopoConnRowStatus set to 'active(1)').
ROW ptopoConnRowStatus	1.3.6.1.2.1.79.1.1.1.1.16	RowStatus	read-create	The status of this conceptual row.
ptopoGeneral	1.3.6.1.2.1.79.1.2
TIM ptopoLastChangeTime	1.3.6.1.2.1.79.1.2.1	TimeStamp	read-only	The value of sysUpTime at the time a conceptual row is created, modified, or deleted in the ptopoConnTable. An NMS can use this object to reduce polling of the ptopoData group objects.
C32 ptopoConnTabInsertsEx	1.3.6.1.2.1.79.1.2.2	Counter32	read-only	The number of times an entry has been inserted into the ptopoConnTable.
C32 ptopoConnTabDeletes	1.3.6.1.2.1.79.1.2.3	Counter32	read-only	The number of times an entry has been deleted from the ptopoConnTable.
C32 ptopoConnTabDrops	1.3.6.1.2.1.79.1.2.4	Counter32	read-only	The number of times an entry would have been added to the ptopoConnTable, (e.g., via information learned from a topology protocol), but was not because of insufficient resources.
C32 ptopoConnTabAgeouts	1.3.6.1.2.1.79.1.2.5	Counter32	read-only	The number of times an entry has been deleted from the ptopoConnTable because the information timeliness interval for that entry has expired.
ptopoConfig	1.3.6.1.2.1.79.1.3
I32 ptopoConfigTrapInterval	1.3.6.1.2.1.79.1.3.1	Integer32	read-write	This object controls the transmission of PTOPO notifications. If this object has a value of zero, then no ptopoConfigChange notifications will be transmitted by the agent. If this object has a non-zero value, then the agent must not generate more than one ptopoConfigChange trap-event in the indicated period, where a 'trap-event' is the transmission of a single notification PDU type to a list of notification destinations. If additional configuration changes occur within the indicated throttling period, then these trap- events must be suppressed by the agent. An NMS should periodically check the value of ptopoLastChangeTime to detect any missed ptopoConfigChange trap-events, e.g. due to throttling or transmission loss. If notification transmission is enabled, the suggested default throttling period is 60 seconds, but transmission should be disabled by default. If the agent is capable of storing non-volatile configuration, then the value of this object must be restored after a re-initialization of the management system.
I32 ptopoConfigMaxHoldTime	1.3.6.1.2.1.79.1.3.2	Integer32	read-write	This object specifies the desired time interval for which an agent will maintain dynamic ptopoConnEntries. After the specified number of seconds since the last time an entry was verified, in the absence of new verification (e.g., receipt of a topology protocol message), the agent shall remove the entry. Note that entries may not always be removed immediately, but may possibly be removed at periodic garbage collection intervals. This object only affects dynamic ptopoConnEntries, i.e. for which ptopoConnIsStatic equals 'false(2)'. Static entries are not aged out. Note that dynamic ptopoConnEntries may also be removed by the agent due to the expired timeliness of learned topology information (e.g., timeliness interval for a remote port expires). The actual age-out interval for a given entry is defined by the following formula: age-out-time = min(ptopoConfigMaxHoldTime, ) where is determined by the discovery algorithm, and may be different for each entry.
ptopoMIBNotifications	1.3.6.1.2.1.79.2
ptopoMIBTrapPrefix	1.3.6.1.2.1.79.2.0
NTF ptopoConfigChange	1.3.6.1.2.1.79.2.0.1			A ptopoConfigChange notification is sent when the value of ptopoLastChangeTime changes. It can be utilized by an NMS to trigger physical topology table maintenance polls. Note that transmission of ptopoConfigChange notifications are throttled by the agent, as specified by the 'ptopoConfigTrapInterval' object.
ptopoRegistrationPoints	1.3.6.1.2.1.79.3
ptopoDiscoveryMechanisms	1.3.6.1.2.1.79.3.1
ptopoDiscoveryLocal	1.3.6.1.2.1.79.3.1.1
ptopoConformance	1.3.6.1.2.1.79.4
ptopoCompliances	1.3.6.1.2.1.79.4.1
ptopoCompliance	1.3.6.1.2.1.79.4.1.1			The compliance statement for SNMP entities which implement the PTOPO MIB.
ptopoGroups	1.3.6.1.2.1.79.4.2
ptopoDataGroup	1.3.6.1.2.1.79.4.2.1			The collection of objects which are used to represent physical topology information for which a single agent provides management information. This group is mandatory for all implementations of the PTOPO MIB.
ptopoGeneralGroup	1.3.6.1.2.1.79.4.2.2			The collection of objects which are used to report the general status of the PTOPO MIB implementation. This group is mandatory for all agents which implement the PTOPO MIB.
ptopoConfigGroup	1.3.6.1.2.1.79.4.2.3			The collection of objects which are used to configure the PTOPO MIB implementation behavior. This group is mandatory for agents which implement the PTOPO MIB.
ptopoNotificationsGroup	1.3.6.1.2.1.79.4.2.4			The collection of notifications used to indicate PTOPO MIB data consistency and general status information. This group is mandatory for agents which implement the PTOPO MIB.

RFC description

Physical topology MIB for discovering and managing physical network connections between devices.

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