ROHC-MIB

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Organization: IETF Robust Header Compression Working Group

Last Updated: 2004-06-03

Category: Header Compression

Description: Defines managed objects for monitoring running instances of RObust Header Compression (ROHC).

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

What Is ROHC-MIB?

ROHC-MIB is a vendor-neutral, IETF standards-based module for monitoring and configuring RObust Header Compression (ROHC) instances running at IP interfaces, commonly used to compress IP/UDP/RTP headers over low-bandwidth or lossy links such as cellular access. It exposes feedback-channel definitions and compressor/decompressor instance information, including instance type, vendor, and the feedback channel it's associated with, while explicitly leaving profile-specific compression-context detail to separate per-profile MIBs. As a protocol/software-status MIB it lets an operator confirm which ROHC compressor or decompressor instances are running on which interfaces and channels, useful for diagnosing header-compression failures on constrained links rather than exposing hardware sensor data. It explicitly defers detailed context-level information to separate per-profile ROHC MIB modules, making it dependent on those companion modules for full visibility. Per the ROHC-MIB RFC, it's deployed on routers, gateways, or mobile-network edge devices using ROHC to reduce header overhead on constrained links.

IPNetwork Monitor allows you to monitor SNMP objects defined in ROHC-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 — applies to routers/gateways using IP header compression, e.g. cellular network edge equipment

Monitoring Examples

rohcChannelTable/rohcChannelEntry would be polled for rohcChannelType and rohcChannelStatus to confirm a feedback channel between compressor and decompressor is active. rohcInstanceTable/rohcInstanceEntry lets an operator check rohcInstanceType and rohcInstanceVendor to verify which ROHC instance is bound to a given rohcInstanceFBChannelID, helping diagnose a case where header-compression negotiation is failing on a particular link.

What Can Be Monitored

ROHC channel type and status
compressor/decompressor instance type
instance vendor
feedback channel association

Imported Objects

From IF-MIB

ifIndex

OBJECT-TYPE

From SNMP-FRAMEWORK-MIB

SnmpAdminString

From SNMPv2-CONF

MODULE-COMPLIANCE
OBJECT-GROUP

From SNMPv2-SMI

Counter32
MODULE-IDENTITY
OBJECT-TYPE
Unsigned32
mib-2

From SNMPv2-TC

DateAndTime
TEXTUAL-CONVENTION
TimeInterval
TruthValue

How to Use in IPNetwork Monitor

Example using rohcInstanceContextsTotal OID:

Select a device implementing ROHC-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 rohcInstanceContextsTotal into the Find box to locate it in the OID tree, selecting the specific row/instance you want to monitor since this is a table column, then select it and click OK. It reports the counter of all contexts created by this instance. 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, 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
rohcMIB	1.3.6.1.2.1.112			This MIB module defines a set of basic objects for monitoring and configuring robust header compression. The module covers information about running instances of ROHC (compressors or decompressors) at IP interfaces. Information about compressor contexts and decompressor contexts has different structure for different profiles. Therefore it is not provided by this MIB module, but by individual modules for different profiles. Copyright (C) The Internet Society (2004). The initial version of this MIB module was published in RFC 3816. For full legal notices see the RFC itself or see: http://www.ietf.org/copyrights/ianamib.html
rohcObjects	1.3.6.1.2.1.112.1
rohcInstanceObjects	1.3.6.1.2.1.112.1.1
rohcChannelTable	1.3.6.1.2.1.112.1.1.1		not-accessible	This table lists and describes all ROHC channels per interface.
rohcChannelEntry	1.3.6.1.2.1.112.1.1.1.1		not-accessible	An entry describing a particular script. Every script that is stored in non-volatile memory is required to appear in this script table. Note, that the rohcChannelID identifies the channel uniquely. The ifIndex is part of the index of this table just in order to allow addressing channels per interface.
OID rohcChannelID	1.3.6.1.2.1.112.1.1.1.1.2	RohcChannelIdentifier	not-accessible	The locally arbitrary, but unique identifier associated with this channel. The value is REQUIRED to be unique per ROHC MIB implementation independent of the associated interface. The value is REQUIRED to remain constant at least from one re-initialization of the entity's network management system to the next re-initialization. It is RECOMMENDED that the value persist across such re-initializations.
INT rohcChannelType	1.3.6.1.2.1.112.1.1.1.1.3	INTEGER	read-only	Type of usage of the channel. A channel might be currently not in use for ROHC or feedback, it might be in use as a ROHC channel carrying packets and optional piggy-backed feedback, or it might be used as a dedicated feedback channel exclusively carrying feedback.
OID rohcChannelFeedbackFor	1.3.6.1.2.1.112.1.1.1.1.4	RohcChannelIdentifierOrZero	read-only	The index of another channel of this interface for which the channel serves as feedback channel. If no feedback information is transferred on this channel, then the value of this ID is 0. If the channel type is set to notInUse(1), then the value of this object must be 0. If the channel type is rohc(2) and the value of this object is a valid channel ID, then feedback information is piggy-backed on the ROHC channel. If the channel type is dedicatedFeedback(3), then feedback is transferred on this channel and the value of this object MUST be different from 0 and MUST identify an existing ROHC channel.
STR rohcChannelDescr	1.3.6.1.2.1.112.1.1.1.1.5	SnmpAdminString	read-only	A textual description of the channel.
INT rohcChannelStatus	1.3.6.1.2.1.112.1.1.1.1.6	INTEGER	read-only	Status of the channel.
rohcInstanceTable	1.3.6.1.2.1.112.1.1.2		not-accessible	This table lists properties of running instances of robust header compressors and decompressors at IP interfaces. It is indexed by interface number, the type of instance (compressor or decompressor), and the ID of the channel used by the instance as ROHC channel. Note that the rohcChannelID uniquely identifies an instance. The ifIndex and rohcInstanceType are part of the index, because it simplifies accessing instances per interface and for addressing either compressors or decompressors only.
rohcInstanceEntry	1.3.6.1.2.1.112.1.1.2.1		not-accessible	An entry describing a particular instance of a robust header compressor or decompressor.
INT rohcInstanceType	1.3.6.1.2.1.112.1.1.2.1.2	INTEGER	not-accessible	Type of the instance of ROHC. It is either a compressor instance or a decompressor instance.
OID rohcInstanceFBChannelID	1.3.6.1.2.1.112.1.1.2.1.4	RohcChannelIdentifierOrZero	read-only	Identifier of the channel used for feedback. If no feedback channel is used, the value of this object is 0 .
OID rohcInstanceVendor	1.3.6.1.2.1.112.1.1.2.1.5	OBJECT IDENTIFIER	read-only	An object identifier that identifies the vendor who provides the implementation of robust header description. This object identifier SHALL point to the object identifier directly below the enterprise object identifier {1 3 6 1 4 1} allocated for the vendor. The value must be the object identifier {0 0} if the vendor is not known.
STR rohcInstanceVersion	1.3.6.1.2.1.112.1.1.2.1.6	SnmpAdminString	read-only	The version number of the implementation of robust header compression. The zero-length string shall be used if the implementation does not have a version number. It is suggested that the version number consist of one or more decimal numbers separated by dots, where the first number is called the major version number.
STR rohcInstanceDescr	1.3.6.1.2.1.112.1.1.2.1.7	SnmpAdminString	read-only	A textual description of the implementation.
U32 rohcInstanceClockRes	1.3.6.1.2.1.112.1.1.2.1.8	Unsigned32	read-only	This object indicates the system clock resolution in units of milliseconds. A zero (0) value means that there is no clock available.
U32 rohcInstanceMaxCID	1.3.6.1.2.1.112.1.1.2.1.9	Unsigned32	read-only	The highest context ID number to be used by the compressor. Note that this parameter is not coupled to, but in effect further constrained by, rohcChannelLargeCIDs.
T/F rohcInstanceLargeCIDs	1.3.6.1.2.1.112.1.1.2.1.10	TruthValue	read-only	When retrieved, this boolean object returns false if the short CID representation (0 bytes or 1 prefix byte, covering CID 0 to 15) is used; it returns true, if the embedded CID representation (1 or 2 embedded CID bytes covering CID 0 to 16383) is used.
U32 rohcInstanceMRRU	1.3.6.1.2.1.112.1.1.2.1.11	Unsigned32	read-only	Maximum reconstructed reception unit. This is the size of the largest reconstructed unit in octets that the decompressor is expected to reassemble from segments (see RFC 3095, Section 5.2.5). Note that this size includes the CRC. If MRRU is negotiated to be 0, no segment headers are allowed on the channel.
NUM rohcInstanceContextStorageTime	1.3.6.1.2.1.112.1.1.2.1.12	TimeInterval	read-write	This object indicates the default maximum amount of time information on a context belonging to this instance is kept as entry in the rohcContextTable after the context is expired or terminated. The value of this object is used to initialize rohcContexStorageTime object when a new context is created. Changing the value of an rohcInstanceContextStorageTime instance does not affect any entry of the rohcContextTable created previously. ROHC-MIB implementations SHOULD store the set value of this object persistently.
INT rohcInstanceStatus	1.3.6.1.2.1.112.1.1.2.1.13	INTEGER	read-only	Status of the instance of ROHC.
C32 rohcInstanceContextsTotalEx	1.3.6.1.2.1.112.1.1.2.1.14	Counter32	read-only	Counter of all contexts created by this instance. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime.
U32 rohcInstanceContextsCurrent	1.3.6.1.2.1.112.1.1.2.1.15	Unsigned32	read-only	Number of currently active contexts created by this instance.
C32 rohcInstancePackets	1.3.6.1.2.1.112.1.1.2.1.16	Counter32	read-only	Counter of all packets passing this instance. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime.
C32 rohcInstanceIRs	1.3.6.1.2.1.112.1.1.2.1.17	Counter32	read-only	The number of all IR packets that are either sent or received by this instance. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime.
C32 rohcInstanceIRDYNs	1.3.6.1.2.1.112.1.1.2.1.18	Counter32	read-only	The number of all IR-DYN packets that are either sent or received by this instance. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime.
C32 rohcInstanceFeedbacks	1.3.6.1.2.1.112.1.1.2.1.19	Counter32	read-only	The number of all feedbacks that are either sent or received by this instance. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime.
ROH rohcInstanceCompressionRatio	1.3.6.1.2.1.112.1.1.2.1.20	RohcCompressionRatio	read-only	This object indicates the compression ratio so far over all packets on the channel served by this instance. The compression is computed over all bytes of the IP packets including the IP header but excluding all lower layer headers.
rohcProfileTable	1.3.6.1.2.1.112.1.1.3		not-accessible	This table lists a set of profiles supported by the instance.
rohcProfileEntry	1.3.6.1.2.1.112.1.1.3.1		not-accessible	An entry describing a particular profile supported by the instance. It is indexed by the rohcChannelID identifying the instance and by the rohcProfile.
U32 rohcProfile	1.3.6.1.2.1.112.1.1.3.1.2	Unsigned32	not-accessible	Identifier of a profile supported. For a listing of possible profile values, see the IANA registry for 'RObust Header Compression (ROHC) Profile Identifiers' at http://www.iana.org/assignments/rohc-pro-ids
OID rohcProfileVendor	1.3.6.1.2.1.112.1.1.3.1.3	OBJECT IDENTIFIER	read-only	An object identifier that identifies the vendor who provides the implementation of robust header description. This object identifier SHALL point to the object identifier directly below the enterprise object identifier {1 3 6 1 4 1} allocated for the vendor. The value must be the object identifier {0 0} if the vendor is not known.
STR rohcProfileVersion	1.3.6.1.2.1.112.1.1.3.1.4	SnmpAdminString	read-only	The version number of the implementation of robust header compression. The zero-length string shall be used if the implementation does not have a version number. It is suggested that the version number consist of one or more decimal numbers separated by dots, where the first number is called the major version number.
STR rohcProfileDescr	1.3.6.1.2.1.112.1.1.3.1.5	SnmpAdminString	read-only	A textual description of the implementation.
T/F rohcProfileNegotiated	1.3.6.1.2.1.112.1.1.3.1.6	TruthValue	read-only	When retrieved, this boolean object returns true if the profile has been negotiated to be used at the instance, i.e., is supported also be the corresponding compressor/decompressor.
rohcContextTable	1.3.6.1.2.1.112.1.2		not-accessible	This table lists and describes all compressor contexts per instance.
rohcContextEntry	1.3.6.1.2.1.112.1.2.1		not-accessible	An entry describing a particular compressor context.
U32 rohcContextCID	1.3.6.1.2.1.112.1.2.1.2	Unsigned32	not-accessible	The context identifier (CID) of this context.
INT rohcContextCIDState	1.3.6.1.2.1.112.1.2.1.3	INTEGER	read-only	State of the CID. When a CID is assigned to a context, its state changes from `unused' to `active'. The active context may stop operation due to some explicit signalling or after observing no packet for some specified time. In the first case then the CID state changes to `terminated', in the latter case it changes to `expired'. If the CID is re-used again for another context, the state changes back to `active'.
U32 rohcContextProfile	1.3.6.1.2.1.112.1.2.1.4	Unsigned32	read-only	Identifier of the profile for this context. The profile is identified by its index in the rohcProfileTable for this instance. There MUST exist a corresponding entry in the rohcProfileTable using the value of rohcContextProfile as second part of the index (and using the same rohcChannelID as first part of the index).
U32 rohcContextDecompressorDepth	1.3.6.1.2.1.112.1.2.1.5	Unsigned32	read-only	This object indicates whether reverse decompression, for example as described in RFC 3095, Section 6.1, is used on this channel or not, and if used, to what extent. Its value is only valid for decompressor contexts, i.e., if rohcInstanceType has the value decompressor(2). For compressor contexts where rohcInstanceType has the value compressor(1), the value of this object is irrelevant and MUST be set to zero (0). The value of the reverse decompression depth indicates the maximum number of packets that are buffered, and thus possibly be reverse decompressed by the decompressor. A zero (0) value means that reverse decompression is not used.
NUM rohcContextStorageTime	1.3.6.1.2.1.112.1.2.1.6	TimeInterval	read-write	The value of this object specifies how long this row can exist in the rohcContextTable after the rohcContextCIDState switched to expired(3) or terminated(4). This object returns the remaining time that the row may exist before it is aged out. The object is initialized with the value of the associated rohcContextStorageTime object. After expiration or termination of the context, the value of this object ticks backwards. The entry in the rohcContextTable is destroyed when the value reaches 0. The value of this object may be set in order to increase or reduce the remaining time that the row may exist. Setting the value to 0 will destroy this entry as soon as the rochContextCIDState has the value expired(3) or terminated(4). Note that there is no guarantee that the row is stored as long as this object indicates. In case of limited CID space, the instance may re-use a CID before the storage time of the corresponding row in rohcContextTable reaches the value of 0. In this case the information stored in this row is not anymore available.
DAT rohcContextActivationTime	1.3.6.1.2.1.112.1.2.1.7	DateAndTime	read-only	The date and time when the context started to be able to compress packets or decompress packets, respectively. The value '0000000000000000'H is returned if the context has not been activated yet.
DAT rohcContextDeactivationTime	1.3.6.1.2.1.112.1.2.1.8	DateAndTime	read-only	The date and time when the context stopped being able to compress packets or decompress packets, respectively, because it expired or was terminated for other reasons. The value '0000000000000000'H is returned if the context has not been deactivated yet.
C32 rohcContextPackets	1.3.6.1.2.1.112.1.2.1.9	Counter32	read-only	The number of all packets passing this context. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime. For checking ifCounterDiscontinuityTime, the interface index is required. It can be determined by reading the rohcChannelTable.
C32 rohcContextIRs	1.3.6.1.2.1.112.1.2.1.10	Counter32	read-only	The number of all IR packets sent or received, respectively, by this context. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime. For checking ifCounterDiscontinuityTime, the interface index is required. It can be determined by reading the rohcChannelTable.
C32 rohcContextIRDYNs	1.3.6.1.2.1.112.1.2.1.11	Counter32	read-only	The number of all IR-DYN packets sent or received, respectively, by this context. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime. For checking ifCounterDiscontinuityTime, the interface index is required. It can be determined by reading the rohcChannelTable.
C32 rohcContextFeedbacks	1.3.6.1.2.1.112.1.2.1.12	Counter32	read-only	The number of all feedbacks sent or received, respectively, by this context. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime. For checking ifCounterDiscontinuityTime, the interface index is required. It can be determined by reading the rohcChannelTable.
C32 rohcContextDecompressorFailures	1.3.6.1.2.1.112.1.2.1.13	Counter32	read-only	The number of all decompressor failures so far in this context. The number is only valid for decompressor contexts, i.e., if rohcInstanceType has the value decompressor(2). Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime. For checking ifCounterDiscontinuityTime, the interface index is required. It can be determined by reading the rohcChannelTable.
C32 rohcContextDecompressorRepairs	1.3.6.1.2.1.112.1.2.1.14	Counter32	read-only	The number of all context repairs so far in this context. The number is only valid for decompressor contexts, i.e., if rohcInstanceType has the value decompressor(2). Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime. For checking ifCounterDiscontinuityTime, the interface index is required. It can be determined by reading the rohcChannelTable.
ROH rohcContextAllPacketsRatio	1.3.6.1.2.1.112.1.2.1.15	RohcCompressionRatio	read-only	This object indicates the compression ratio so far over all packets passing this context. The compression is computed over all bytes of the IP packets including the IP header but excluding all lower layer headers.
ROH rohcContextAllHeadersRatio	1.3.6.1.2.1.112.1.2.1.16	RohcCompressionRatio	read-only	This object indicates the compression ratio so far over all packet headers passing this context. The compression is computed over all bytes of all headers that are subject to compression for the used profile.
U32 rohcContextAllPacketsMeanSize	1.3.6.1.2.1.112.1.2.1.17	Unsigned32	read-only	This object indicates the mean compressed packet size of all packets passing this context. The packet size includes the IP header and payload but excludes all lower layer headers. The mean value is given in byte rounded to the next integer value.
U32 rohcContextAllHeadersMeanSize	1.3.6.1.2.1.112.1.2.1.18	Unsigned32	read-only	This object indicates the mean compressed packet header size of all packets passing this context. The packet header size is the sum of the size of all headers of a packet that are subject to compression for the used profile. The mean value is given in byte rounded to the next integer value.
ROH rohcContextLastPacketsRatio	1.3.6.1.2.1.112.1.2.1.19	RohcCompressionRatio	read-only	This object indicates the compression ratio concerning the last 16 packets passing this context or concerning all packets passing this context if they are less than 16, so far. The compression is computed over all bytes of the IP packets including the IP header but excluding all lower layer headers.
ROH rohcContextLastHeadersRatio	1.3.6.1.2.1.112.1.2.1.20	RohcCompressionRatio	read-only	This object indicates the compression ratio concerning the headers of the last 16 packets passing this context or concerning the headers of all packets passing this context if they are less than 16, so far. The compression is computed over all bytes of all headers that are subject to compression for the used profile.
U32 rohcContextLastPacketsMeanSize	1.3.6.1.2.1.112.1.2.1.21	Unsigned32	read-only	This object indicates the mean compressed packet size concerning the last 16 packets passing this context or concerning all packets passing this context if they are less than 16, so far. The packet size includes the IP header and payload but excludes all lower layer headers. The mean value is given in byte rounded to the next integer value.
U32 rohcContextLastHeadersMeanSize	1.3.6.1.2.1.112.1.2.1.22	Unsigned32	read-only	This object indicates the mean compressed packet header size concerning the last 16 packets passing this context or concerning all packets passing this context if they are less than 16, so far. The packet header size is the sum of the size of all headers of a packet that are subject to compression for the used profile. The mean value is given in byte rounded to the next integer value.
rohcConformance	1.3.6.1.2.1.112.2
rohcCompliances	1.3.6.1.2.1.112.2.1
rohcCompliance	1.3.6.1.2.1.112.2.1.1			The compliance statement for SNMP entities that implement the ROHC-MIB. Note that compliance with this compliance statement requires compliance with the ifCompliance3 MODULE-COMPLIANCE statement of the IF-MIB (RFC2863).
rohcGroups	1.3.6.1.2.1.112.2.2
rohcInstanceGroup	1.3.6.1.2.1.112.2.2.2			A collection of objects providing information about ROHC instances, used channels and available profiles.
rohcStatisticsGroup	1.3.6.1.2.1.112.2.2.4			A collection of objects providing ROHC statistics.
rohcContextGroup	1.3.6.1.2.1.112.2.2.5			A collection of objects providing information about ROHC compressor contexts and decompressor contexts.
rohcTimerGroup	1.3.6.1.2.1.112.2.2.6			A collection of objects providing statistical information about ROHC compressor contexts and decompressor contexts.
rohcContextStatisticsGroup	1.3.6.1.2.1.112.2.2.7			A collection of objects providing statistical information about ROHC compressor contexts and decompressor contexts.

RFC description

SNMP MIB for RObust Header Compression (ROHC) protocol that provides efficient header compression for RTP/UDP/IP, UDP/IP, and ESP/IP headers over various link technologies.

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