TCP Monitoring

The tcp group manages information about TCP connections. It has 14 variables, a table called tcpConnTable and the OID 1.3.6.1.2.1.6(mib.tcp).

OID      Name                Datatype      Writable Description

1        tcpRtoAlgorithm   INTEGER        no        This variable indicates the algorithm used to calculate the timeout value for

                                                                      retransmitting unacknowledged octets. Possible values are: 1(none of the

                                                                      following), 2(a constant RTO), 3(MIL-STD-1778), 4(Van Jacobson's algorithm)

2        tcpRtoMin         INTEGER        no        Minimum timeout value permitted in a TCP implementation for the

                                                                      retransmission in milliseconds

3        tcpRtoMax         INTEGER        no        Maximum timeout value permitted in a TCP implementation for the

                                                                      retransmission in milliseconds

4        tcpMaxConn         INTEGER        no        Maximum number of TCP connection this entity supports

5        tcpActiveOpens         Counter        no        Total number of transitions to SYN_SENT state from CLOSED state

6        tcpPassiveOpens  Counter        no        Total number of transitions to SYN_RCVD state from LISTEN state

7        tcpAttemptFails         Counter        no        Total number of transitions to the CLOSED state from SYN_SENT or

                                                                      SYNRCVD states plus the transitions to LISTEN from SYN_RCVD

8        tcpEstabRestes         Counter        no        Total number of transitions to CLOSED state from ESTABLISHED or

                                                                      CLOSE-WAIT states

9        tcpCurrEstab       Gauge                   no        Number of currently TCP connections in ESTABLISHED or CLOSE-WAIT

                                                                      states

10        tcpInSegs         Counter        no        Total number of segments received

11        tcpOutsegs         Counter        no        Total number of segments sent, excluding those containing only retranmitted

                                                                      octets

12        tcpRetransSegs         Counter        no        Number of segments transmitted with one or more previouly transmitted

                                                                      octets

14        tcpInErrs         Counter        no        Number of received segments with an error

15        tcpOutRsts         Counter        no        Number of transmitted segments with the RST flag set

The following table is tcpConnTable. It has the OID 13 and a row for each TCP connection:

OID      Name                           Datatype    Writable   Description

1        tcpConnState                   INTEGER        yes        Indicates the current state of the TCP connection. The user can only

                                                                                  set the value 12, but can read: 1(closed), 2(listen), 3(synSent),

                                                                                  4(synReceived), 5(established), 6(finWait1), 7(finWait2), 8(closeWait),

                                                                                  9(lastAck), 10(closing), 11(timeWait), 12(deleteTCB)

2        tcpConnLocalAddress        IpAddress        no        Local IP address of the current connection. The value 0.0.0.0 indicates

                                                                                  that the listener is willing to accept TCP connections on any interface

3        tcpConnLocalPort        Integer        no                   Local port number of this TCP connection

4        tcpConnRemAddress        IpAddress        no        Remote IP address of this TCP connection

5        tcpConnRemPort        Integer                   no        Remote port number of the current TCP connection