Request for Comments: 4022 Cisco Systems
Obsoletes: 2452, 2012 March 2005
Category: Standards Track
Management Information Base
for the Transmission Control Protocol (TCP)
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This memo defines a portion of the Management Information Base (MIB)
for use with network management protocols in the Internet community.
In particular, it describes managed objects used for implementations
of the Transmission Control Protocol (TCP) in an IP version
independent manner. This memo obsoletes RFCs 2452 and 2012.
Table of Contents
1. The Internet-Standard Management Framework . . . . . . . . . 2
2. Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.1. Relationship to Other MIBs. . . . . . . . . . . . . . . 2
3. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Acknowledgements. . . . . . . . . . . . . . . . . . . . . . . 20
5. References. . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.1. Normative References. . . . . . . . . . . . . . . . . . 20
5.2. Informative References. . . . . . . . . . . . . . . . . 21
6. Security Considerations . . . . . . . . . . . . . . . . . . . 21
7. Contributors. . . . . . . . . . . . . . . . . . . . . . . . . 23
Editor’s Address. . . . . . . . . . . . . . . . . . . . . . . . . 23
Full Copyright Statement. . . . . . . . . . . . . . . . . . . . . 24
1. The Internet-Standard Management Framework
For a detailed overview of the documents that describe the current
Internet-Standard Management Framework, please refer to section 7 of
RFC 3410 [RFC3410].
Managed objects are accessed via a virtual information store, termed
the Management Information Base or MIB. MIB objects are generally
accessed through the Simple Network Management Protocol (SNMP).
Objects in the MIB are defined using the mechanisms defined in the
Structure of Management Information (SMI). This memo specifies a MIB
module that is compliant to the SMIv2, which is described in STD 58,
RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579] and STD 58, RFC 2580
[RFC2580].
2. Overview
The current TCP-MIB defined in this memo consists of two tables and a
group of scalars:
- The tcp group of scalars includes two sets of objects:
o Parameters of a TCP protocol engine. These include
parameters such as the retransmission algorithm in use
(e.g., vanj [VANJ]) and the retransmission timeout values.
o Statistics of a TCP protocol engine. These include counters
for the number of active/passive opens, input/output
segments, and errors. Discontinuities in the stats are
identified identified via the sysUpTime object, defined in
[RFC3418].
- The tcpConnectionTable provides access to status information
for all TCP connections handled by a TCP protocol engine. In
addition, the table reports identification of the operating
system level processes that handle the TCP connections.
- The tcpListenerTable provides access to information about all
TCP listening endpoints known by a TCP protocol engine. And as
with the connection table, the tcpListenerTable also reports
the identification of the operating system level processes that
handle this listening TCP endpoint.
2.1. Relationship to Other MIBs
This section discusses the relationship of this TCP-MIB module to
other MIB modules.
2.1.1. Relationship to RFC1213-MIB
TCP related MIB objects were originally defined as part of the
RFC1213-MIB defined in RFC 1213 [RFC1213]. The TCP related objects
of the RFC1213-MIB were later copied into a separate MIB module and
published in RFC 2012 [RFC2012] in SMIv2 format.
The previous versions of the TCP-MIB both defined the tcpConnTable,
which has been deprecated basically for two reasons:
(1) The tcpConnTable only supports IPv4.
The current approach in the IETF is to write IP version neutral
MIBs, based on the InetAddressType and InetAddress constructs
defined in [RFC4001], rather than to have different definitions
for various version of IP. This reduces the amount of overhead
when new objects are introduced, as there is only one place to
add them. Hence, the approach taken in [RFC2452], of having
separate tables, is not continued.
(2) The tcpConnTable mixes listening endpoints with connections.
It turns out that connections tend to have a different behaviour
and management access pattern than listening endpoints.
Therefore, splitting the original tcpConnTable into two tables
allows for the addition of specific status and statistics objects
for listening endpoints and connections.
2.1.2. Relationship to IPV6-TCP-MIB
The IPV6-TCP-MIB defined in RFC 2452 has been moved to Historic
status because the approach of having separate IP version specific
tables is not followed anymore. Implementation of RFC 2452 is no
longer suggested.
2.1.3. Relationship to HOST-RESOURCES-MIB and SYSAPPL-MIB
The tcpConnectionTable and the tcpListenerTable report the
identification of the operating system level process that handles a
connection or a listening endpoint. The value is reported as an
Unsigned32, which is expected to be the same as the hrSWRunIndex of
the HOST-RESOURCES-MIB [RFC2790] (if the value is smaller than
2147483647) or the sysApplElmtRunIndex of the SYSAPPL-MIB [RFC2287].
This allows management applications to identify the TCP connections
that belong to an operating system level process, which has proven to
be valuable in operational environments.
3. Definitions
TCP-MIB DEFINITIONS ::= BEGIN
IMPORTS
MODULE-IDENTITY, OBJECT-TYPE, Integer32, Unsigned32,
Gauge32, Counter32, Counter64, IpAddress, mib-2
FROM SNMPv2-SMI
MODULE-COMPLIANCE, OBJECT-GROUP FROM SNMPv2-CONF
InetAddress, InetAddressType,
InetPortNumber FROM INET-ADDRESS-MIB;
tcpMIB MODULE-IDENTITY
LAST-UPDATED "200502180000Z" -- 18 February 2005
ORGANIZATION
"IETF IPv6 MIB Revision Team
http://www.ietf.org/html.charters/ipv6-charter.html"
CONTACT-INFO
"Rajiv Raghunarayan (editor)
Cisco Systems Inc.
170 West Tasman Drive
San Jose, CA 95134
Phone: +1 408 853 9612
Email: <raraghun@cisco.com>
Send comments to <ipv6@ietf.org>"
DESCRIPTION
"The MIB module for managing TCP implementations.
Copyright (C) The Internet Society (2005). This version
of this MIB module is a part of RFC 4022; see the RFC
itself for full legal notices."
REVISION "200502180000Z" -- 18 February 2005
DESCRIPTION
"IP version neutral revision, published as RFC 4022."
REVISION "9411010000Z"
DESCRIPTION
"Initial SMIv2 version, published as RFC 2012."
REVISION "9103310000Z"
DESCRIPTION
"The initial revision of this MIB module was part of
MIB-II."
::= { mib-2 49 }
-- the TCP base variables group
tcp OBJECT IDENTIFIER ::= { mib-2 6 }
-- Scalars
tcpRtoAlgorithm OBJECT-TYPE
SYNTAX 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
}
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The algorithm used to determine the timeout value used for
retransmitting unacknowledged octets."
::= { tcp 1 }
tcpRtoMin OBJECT-TYPE
SYNTAX Integer32 (0..2147483647)
UNITS "milliseconds"
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"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."
::= { tcp 2 }
tcpRtoMax OBJECT-TYPE
SYNTAX Integer32 (0..2147483647)
UNITS "milliseconds"
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"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)."
::= { tcp 3 }
tcpMaxConn OBJECT-TYPE
SYNTAX Integer32 (-1 | 0..2147483647)
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"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."
::= { tcp 4 }
tcpActiveOpens OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"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."
::= { tcp 5 }
tcpPassiveOpens OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"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."
::= { tcp 6 }
tcpAttemptFails OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"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."
::= { tcp 7 }
tcpEstabResets OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"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."
::= { tcp 8 }
tcpCurrEstab OBJECT-TYPE
SYNTAX Gauge32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of TCP connections for which the current state
is either ESTABLISHED or CLOSE-WAIT."
::= { tcp 9 }
tcpInSegs OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of segments received, including those
received in error. This count includes segments received
on currently established connections.
Discontinuities in the value of this counter are
indicated via discontinuities in the value of sysUpTime."
::= { tcp 10 }
tcpOutSegs OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of segments sent, including those on
current connections but excluding those containing only
retransmitted octets.
Discontinuities in the value of this counter are
indicated via discontinuities in the value of sysUpTime."
::= { tcp 11 }
tcpRetransSegs OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"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."
::= { tcp 12 }
tcpInErrs OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of segments received in error (e.g., bad
TCP checksums).
Discontinuities in the value of this counter are
indicated via discontinuities in the value of sysUpTime."
::= { tcp 14 }
tcpOutRsts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of TCP segments sent containing the RST flag.
Discontinuities in the value of this counter are
indicated via discontinuities in the value of sysUpTime."
::= { tcp 15 }
-- { tcp 16 } was used to represent the ipv6TcpConnTable in RFC 2452,
-- which has since been obsoleted. It MUST not be used.
tcpHCInSegs OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"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."
::= { tcp 17 }
tcpHCOutSegs OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"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."
::= { tcp 18 }
-- The TCP Connection table
tcpConnectionTable OBJECT-TYPE
SYNTAX SEQUENCE OF TcpConnectionEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A table containing information about existing TCP
connections. Note that unlike earlier TCP MIBs, there
is a separate table for connections in the LISTEN state."
::= { tcp 19 }
tcpConnectionEntry OBJECT-TYPE
SYNTAX TcpConnectionEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A conceptual row of the tcpConnectionTable containing
information about a particular current TCP connection.
Each row of this table is transient in that it ceases to
exist when (or soon after) the connection makes the
transition to the CLOSED state."
INDEX { tcpConnectionLocalAddressType,
tcpConnectionLocalAddress,
tcpConnectionLocalPort,
tcpConnectionRemAddressType,
tcpConnectionRemAddress,
tcpConnectionRemPort }
::= { tcpConnectionTable 1 }
TcpConnectionEntry ::= SEQUENCE {
tcpConnectionLocalAddressType InetAddressType,
tcpConnectionLocalAddress InetAddress,
tcpConnectionLocalPort InetPortNumber,
tcpConnectionRemAddressType InetAddressType,
tcpConnectionRemAddress InetAddress,
tcpConnectionRemPort InetPortNumber,
tcpConnectionState INTEGER,
tcpConnectionProcess Unsigned32
}
tcpConnectionLocalAddressType OBJECT-TYPE
SYNTAX InetAddressType
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The address type of tcpConnectionLocalAddress."
::= { tcpConnectionEntry 1 }
tcpConnectionLocalAddress OBJECT-TYPE
SYNTAX InetAddress
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"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, implementors 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."
::= { tcpConnectionEntry 2 }
tcpConnectionLocalPort OBJECT-TYPE
SYNTAX InetPortNumber
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The local port number for this TCP connection."
::= { tcpConnectionEntry 3 }
tcpConnectionRemAddressType OBJECT-TYPE
SYNTAX InetAddressType
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The address type of tcpConnectionRemAddress."
::= { tcpConnectionEntry 4 }
tcpConnectionRemAddress OBJECT-TYPE
SYNTAX InetAddress
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"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, implementors 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."
::= { tcpConnectionEntry 5 }
tcpConnectionRemPort OBJECT-TYPE
SYNTAX InetPortNumber
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The remote port number for this TCP connection."
::= { tcpConnectionEntry 6 }
tcpConnectionState OBJECT-TYPE
SYNTAX 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)
}
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"The state 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