TCP-MIB
Functions Overview
TCP-MIB is defined in RFC 4022. With TCP-MIB, you can obtain related TCP parameters such as the retransmission algorithm and retransmission delay and statistics about TCP packets such as the number of received and received packets by performing the Get or Get Next operation. In addition, TCP-MIB allows you to perform the Set operation on tcpConnectionState and tcpConnState so as to close a specific connection.
TCP-MIB contains the following contents:
Simple variables: are used to describe TCP operation parameters and save statistics.
tcpConnectionTable: is used to describe TCP connections. It stores the network information (such as the address and port number) and current status of each TCP connection.
tcpListenerTable: is used to describe all TCP listening endpoints of the system.
Besides the preceding contents, TCP-MIB of the current version contains tcpConnTable defined in RFC 1213. tcpConnTable has been divided into tcpConnectionTable and tcpListenerTable. tcpConnTable is not recommended in RFC 4022. Considering forward compatibility, tcpConnTable is reserved and the Set operation can be performed on any object in tcpConnTable.
Root directory:
iso(1).org(3).dod(6).internet(1).mgmt(2).mib-2(1).tcp(6)
Relationships Between Tables
tcpConnTable stores information not only about TCP listeners but also about TCP connections, whereas tcpConnectionTable stores only information about established TCP connections. The information about an established TCP connection in tcpConnTable is the same as that in tcpConnectionTable.
tcpConnTable stores information not only about TCP listener but also about TCP connections, whereas tcpListenerTable stores only information about TCP listeners. The information about listeners in tcpConnTable is the same as that in tcpListenerTable.
Description of Single Objects
tcpRtoAlgorithm
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.1 |
tcpRtoAlgorithm |
INTEGER { other(1), -- none of the following constant(2), -- a constant rto rsre(3), -- MIL-STD-1778, Appendix B vanj(4), -- Van Jacobson's algorithm rfc2988(5) -- RFC 2988 } |
Read-only |
The algorithm used to determine the timeout value used for retransmitting unacknowledged octets. |
Currently, the TCP module on the switches support the Van Jacobson algorithm (4) used to calculate the retransmission delay. Therefore, the result of the Get or Get Next operation can only be 4. |
tcpRtoMin
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.2 |
tcpRtoMin |
Integer32 (0..2147483647) |
Read-only |
The minimum value permitted by a TCP implementation for the retransmission timeout, measured in milliseconds. More refined semantics for objects of this type depend on the algorithm used to determine the retransmission timeout; in particular, the IETF standard algorithm rfc2988(5) provides a minimum value. |
This object is implemented as defined in the corresponding MIB files. |
tcpRtoMax
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.3 |
tcpRtoMax |
Integer32 (0..2147483647) |
Read-only |
The maximum value permitted by a TCP implementation for the retransmission timeout, measured in milliseconds. More refined semantics for objects of this type depend on the algorithm used to determine the retransmission timeout; in particular, the IETF standard algorithm rfc2988(5) provides an upper bound (as part of an adaptive backoff algorithm). |
This object is implemented as defined in the corresponding MIB files. |
tcpMaxConn
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.4 |
tcpMaxConn |
Integer32 (-1 | 0..2147483647) |
Read-only |
The value of this object identifies the limit on the total number of TCP connections the entity can support. In entities where the maximum number of connections is dynamic, this object should contain the value -1. |
Currently, the maximum number of connections supported by the TCP module of the switches support dynamically increases. Therefore, the operation result of tcpMaxConn can only be -1. |
tcpActiveOpens
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.5 |
tcpActiveOpens |
INTEGER (0..4294967295) |
Read-only |
The number of times that TCP connections have made a direct transition to the SYN-SENT state from the CLOSED state. Discontinuities in the value of this counter are indicated via discontinuities in the value of sysUpTime. |
This object is implemented as defined in the corresponding MIB files. |
tcpPassiveOpens
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.6 |
tcpPassiveOpens |
INTEGER (0..4294967295) |
Read-only |
The number of times TCP connections have made a direct transition to the SYN-RCVD state from the LISTEN state. Discontinuities in the value of this counter are indicated via discontinuities in the value of sysUpTime. |
This object is implemented as defined in the corresponding MIB files. |
tcpAttemptFails
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.7 |
tcpAttemptFails |
INTEGER (0..4294967295) |
Read-only |
The number of times that TCP connections have made a direct transition to the CLOSED state from either the SYN-SENT state or the SYN-RCVD state, plus the number of times that TCP connections have made a direct transition to the LISTEN state from the SYN-RCVD state. Discontinuities in the value of this counter are indicated via discontinuities in the value of sysUpTime. |
This object is implemented as defined in the corresponding MIB files. |
tcpEstabResets
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.8 |
tcpEstabResets |
INTEGER (0..4294967295) |
Read-only |
The number of times that TCP connections have made a direct transition to the CLOSED state from either the ESTABLISHED state or the CLOSE-WAIT state. Discontinuities in the value of this counter are indicated via discontinuities in the value of sysUpTime. |
This object is implemented as defined in the corresponding MIB files. |
tcpCurrEstab
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.9 |
tcpCurrEstab |
INTEGER (0..4294967295) |
Read-only |
The number of TCP connections for which the current state is either ESTABLISHED or CLOSE-WAIT. |
This object is implemented as defined in the corresponding MIB files. |
tcpInSegs
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.10 |
tcpInSegs |
INTEGER (0..4294967295) |
Read-only |
The total number of segments received, including those received in error. This count includes segments received on currently established connections. |
This object is implemented as defined in the corresponding MIB files. |
tcpOutSegs
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.11 |
tcpOutSegs |
INTEGER (0..4294967295) |
Read-only |
The total number of segments sent, including those on current connections but excluding those containing only retransmitted octets. |
This object is implemented as defined in the corresponding MIB files. |
tcpRetransSegs
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.12 |
tcpRetransSegs |
INTEGER (0..4294967295) |
Read-only |
The total number of segments retransmitted; that is, the number of TCP segments transmitted containing one or more previously transmitted octets. Discontinuities in the value of this counter are indicated via discontinuities in the value of sysUpTime. |
This object is implemented as defined in the corresponding MIB files. |
tcpInErrs
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.14 |
tcpInErrs |
INTEGER (0..4294967295) |
Read-only |
The total number of segments received in error (for example, bad TCP checksums). |
This object is implemented as defined in the corresponding MIB files. |
tcpOutRsts
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.15 |
tcpOutRsts |
INTEGER (0..4294967295) |
Read-only |
The number of TCP segments sent containing the RST flag. |
This object is implemented as defined in the corresponding MIB files. |
tcpHCInSegs
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.17 |
tcpHCInSegs |
INTEGER (0..18446744073709551615) |
Read-only |
The total number of segments received, including those received in error. This count includes segments received on currently established connections. This object is the 64-bit equivalent of tcpInSegs. Discontinuities in the value of this counter are indicated via discontinuities in the value of sysUpTime. |
This object is implemented as defined in the corresponding MIB files. |
tcpHCOutSegs
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.18 |
tcpHCOutSegs |
INTEGER (0..18446744073709551615) |
Read-only |
The total number of segments sent, including those on current connections but excluding those containing only retransmitted octets. This object is the 64-bit equivalent of tcpOutSegs. Discontinuities in the value of this counter are indicated via discontinuities in the value of sysUpTime. |
This object is implemented as defined in the corresponding MIB files. |
Description of MIB Tables
tcpConnTable
tcpConnTable stores the information about all IPv4 TCP listeners, connection interfaces, and endpoints that can receive data packets or connection requests. This table contains five objects: tcpConnState, tcpConnLocalAddress, tcpConnLocalPort, tcpConnRemAddress, and tcpConnRemPort.
The indexes of this table are tcpConnLocalAddress, tcpConnLocalPort, tcpConnRemAddress, and tcpConnRemPort.
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.13.1.1 |
tcpConnState |
INTEGER{ closed(1), listen(2), synSent(3), synReceived(4), established(5), finWait1(6), finWait2(7), closeWait(8), lastAck(9), closing(10), timeWait(11), deleteTCB(12) } |
Read-write |
The value of this object identifies the status of this TCP connection. The only value which may be set by a management station is deleteTCB(12). Accordingly, it is appropriate for an agent to return a 'badValue' response if a management station attempts to set this object to any other value. If a management station sets this object to the value deleteTCB(12), then this has the effect of deleting the TCB (as defined in RFC 793) of the corresponding connection on the managed object, resulting in immediate termination of the connection. As an implementation-specific option, an RST segment may be sent from the managed node to the other TCP endpoint (note however that RST segments are not sent reliably). |
Currently, the supported maximum access is read-only. |
1.3.6.1.2.1.6.13.1.2 |
tcpConnLocalAddress |
OCTET STRING (SIZE (4)) |
Read-only |
The local IP address for this TCP connection. In the case of a connection in the listen state which is willing to accept connections for any IP interface associated with the object, the value 0.0.0.0 is used. |
This object is implemented as defined in the corresponding MIB file. |
1.3.6.1.2.1.6.13.1.3 |
tcpConnLocalPort |
INTEGER (0...65535) |
Read-only |
The local port number for this TCP connection. |
This object is implemented as defined in the corresponding MIB file. |
1.3.6.1.2.1.6.13.1.4 |
tcpConnRemAddress |
OCTET STRING (SIZE (4)) |
Read-only |
The remote IP address for this TCP connection. |
This object is implemented as defined in the corresponding MIB file. |
1.3.6.1.2.1.6.13.1.5 |
tcpConnRemPort |
INTEGER (0...65535) |
Read-only |
The remote port number for this TCP connection. |
This object is implemented as defined in the corresponding MIB file. |
Creation Restriction
The entries in this table cannot be created.
Modification Restriction
The only value that the management process can set to the tcpConnTable is 12 (For example, terminate the connection immediately).
Deletion Restriction
The entries in this table cannot be deleted.
Access Restriction
None.
tcpConnectionTable
A table containing information about existing TCP connections including IPv4 TCP connections and IPv6 TCP connections. Note that unlike earlier TCP MIBs, there is a separate table for connections in the LISTEN state.
This table contains the following objects:
tcpConnectionLocalAddressType
tcpConnectionLocalAddress
tcpConnectionLocalPort
tcpConnectionRemAddressType
tcpConnectionRemAddress
tcpConnectionRemPort
tcpConnectionState
tcpConnectionProcess
The indexes of this table are tcpConnectionLocalAddressType, tcpConnectionLocalAddress, tcpConnectionLocalPort, tcpConnectionRemAddressType, tcpConnectionRemAddress and tcpConnectionRemPort.
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.19.1.1 |
tcpConnectionLocalAddressType |
INTEGER{unknown(0),ipv4(1),ipv6(2),ipv4z(3),ipv6z(4),dns(16)} |
Not-accessible |
This object indicates the address type of tcpConnectionLocalAddress. |
The value of this object is an enumerated value, and can be IPv4(1), IPv4z(2), IPv6(3), or IPv6z(4). If a TCP socket interface can receive both IPv4 packets and IPv6 packets, the value of this object can also be unknown(0). Currently, the TCP module of the switches support only IPv4(1) and IPv6(3). |
1.3.6.1.2.1.6.19.1.2 |
tcpConnectionLocalAddress |
OCTET STRING (SIZE (0..255)) |
Not-accessible |
The object indicates the local IP address for this TCP connection. The type of this address is determined by the value of tcpConnectionLocalAddressType. As this object is used in the index for the tcpConnectionTable, implementers should be careful not to create entries that would result in OIDs with more than 128 subidentifiers; otherwise the information cannot be accessed by using SNMPv1, SNMPv2c, or SNMPv3. |
This object is implemented as defined in the corresponding MIB file. |
1.3.6.1.2.1.6.19.1.3 |
tcpConnectionLocalPort |
Unsigned32 (0..65535) |
Not-accessible |
This object indicates the local port number for this TCP connection. |
This object is implemented as defined in the corresponding MIB file. |
1.3.6.1.2.1.6.19.1.4 |
tcpConnectionRemAddressType |
INTEGER{unknown(0),ipv4(1),ipv6(2),ipv4z(3),ipv6z(4),dns(16)} |
Not-accessible |
This object indicates the address type of tcpConnectionRemAddress. |
The value of this object is an enumerated value, and can be IPv4(1), IPv4z(2), IPv6(3), and IPv6z(4). If a TCP socket interface can receive both IPv4 packets and IPv6 packets, the value of this object can also be unknown(0). Currently, the TCP module of the switches only support IPv4(1) and IPv6(3). |
1.3.6.1.2.1.6.19.1.5 |
tcpConnectionRemAddress |
OCTET STRING (SIZE (0..255)) |
Not-accessible |
The object indicates the remote IP address for this TCP connection. The type of this address is determined by the value of tcpConnectionRemAddressType. As this object is used in the index for the tcpConnectionTable, implementers should be careful not to create entries that would result in OIDs with more than 128 subidentifiers; otherwise the information cannot be accessed by using SNMPv1, SNMPv2c, or SNMPv3. |
This object is implemented as defined in the corresponding MIB file. |
1.3.6.1.2.1.6.19.1.6 |
tcpConnectionRemPort |
Unsigned32 (0..65535) |
Not-accessible |
This object indicates the remote port number for this TCP connection. |
This object is implemented as defined in the corresponding MIB file. |
1.3.6.1.2.1.6.19.1.7 |
tcpConnectionState |
INTEGER{ closed(1), listen(2), synSent(3), synReceived(4), established(5), finWait1(6), finWait2(7), closeWait(8), lastAck(9), closing(10), timeWait(11), deleteTCB(12) } |
Read-write |
The value of this object identifies the status of this TCP connection. The value listen(2) is included only for parallelism to the old tcpConnTable and should not be used. A connection in LISTEN state should be present in the tcpListenerTable. The only value that may be set by a management station is deleteTCB(12). Accordingly, it is appropriate for an agent to return a `badValue' response if a management station attempts to set this object to any other value. If a management station sets this object to the value deleteTCB(12), then the TCB (as defined in [RFC793]) of the corresponding connection on the managed node is deleted, resulting in immediate termination of the connection. As an implementation-specific option, an RST segment may be sent from the managed node to the other TCP endpoint (note, however, that RST segments are not sent reliably). |
Currently, the supported maximum access is read-only. |
1.3.6.1.2.1.6.19.1.8 |
tcpConnectionProcess |
INTEGER (0..4294967295) |
Read-only |
This object indicates the system's process ID for the process associated with this connection, or zero if there is no such process. This value is expected to be the same as HOST-RESOURCES-MIB:: hrSWRunIndex or SYSAPPL-MIB::sysApplElmtRunIndex for some row in the appropriate tables. |
This object is implemented as defined in the corresponding MIB file. |
Creation Restriction
The entries in this table cannot be created.
Modification Restriction
The only value that the management process can set to the tcpConnectionTable is 12 (For example, terminate the connection immediately).
Deletion Restriction
The entries in this table cannot be deleted.
Access Restriction
The entries in this table can be read only when the system has established TCP connections.
tcpListenerTable
This table contains the information about all TCP listeners including IPv4 TCP listeners and IPv6 TCP listeners.
This table contains the following objects:
tcpListenerLocalAddressType
tcpListenerLocalAddress
tcpListenerLocalPort
tcpListenerProcess
The indexes of this table are tcpListenerLocalAddressType, tcpListenerLocalAddress and tcpListenerLocalPort.
OID |
Object Name |
Syntax |
Max Access |
Description |
Implemented Specifications |
---|---|---|---|---|---|
1.3.6.1.2.1.6.20.1.1 |
tcpListenerLocalAddressType |
INTEGER{unknown(0),ipv4(1),ipv6(2),ipv4z(3),ipv6z(4),dns(16)} |
Not-accessible |
This object indicates the address type of tcpListenerLocalAddress. The value should be unknown (0) if connection initiations to all local IP addresses are accepted. |
The value of this object is an enumerated value, and can be IPv4(1), IPv4z(2), IPv6(3), and IPv6z(4). Currently, the TCP module of the switches support only IPv4(1) and IPv6(3). |
1.3.6.1.2.1.6.20.1.2 |
tcpListenerLocalAddress |
OCTET STRING (SIZE (0..255)) |
Not-accessible |
This object indicates the local IP address for this TCP connection. The value of this object can be represented in three possible ways, depending on the characteristics of the application: 1. For an application willing to accept both IPv4 and IPv6 datagrams, the value of this object must be ''h (a zero-length octet-string), with the value of the corresponding tcpListenerLocalAddressType object being unknown (0). 2. For an application willing to accept only IPv4 or IPv6 datagrams, the value of this object must be '0.0.0.0' or '::' respectively, with tcpListenerLocalAddressType representing the appropriate address type. 3. For an application which is listening for data destined only to a specific IP address, the value of this object is the specific local address, with tcpListenerLocalAddressType representing the appropriate address type. As this object is used in the index for the tcpListenerTable, implementors should be careful not to create entries that would result in OIDs with more than 128 subidentifiers; otherwise the information cannot be accessed, using SNMPv1, SNMPv2c, or SNMPv3. |
This object is implemented as defined in the corresponding MIB file. |
1.3.6.1.2.1.6.20.1.3 |
tcpListenerLocalPort |
Unsigned32 (0..65535) |
Not-accessible |
The local port number for this TCP connection. |
This object is implemented as defined in the corresponding MIB file. |
1.3.6.1.2.1.6.20.1.4 |
tcpListenerProcess |
INTEGER (0..4294967295) |
Read-only |
This object indicates the system's process ID for the process associated with this listener, or zero if there is no such process. This value is expected to be the same as HOST-RESOURCES-MIB:: hrSWRunIndex or SYSAPPL-MIB::sysApplElmtRunIndex for some row in the appropriate tables. |
This object is implemented as defined in the corresponding MIB file. |
Creation Restriction
This table cannot be created.
Modification Restriction
This table cannot be modified.
Deletion Restriction
This table cannot be deleted.
Access Restriction
The entries in this table can be read only when the system has established TCP connections.
The values of tcpListenerLocalAddressType and tcpListenerLocalAddress vary in the following situations:
If an endpoint of an application can receive only IPv4 packets or IPv6 packets, the value of tcpListenerLocalAddressType is 1 (IPv4) or 3 (IPv6), and the value of tcpListenerLocalAddress is 0.0.0.0 (IPv4) or :: (IPv6).
If the endpoint of an application can receive data packets from a certain interface of the local system only, the value of tcpListenerLocalAddressType is 1 (IPv4) or 3 (IPv6), and the value of tcpListenerLocalAddress is the IP address of an interface.