10-3
Viewing TCP Group Information
Rto. Max. (Retransmit time out Maximum)
The maximum value permitted by a TCP implementation for the retransmission
timeout (measured in milliseconds) according to the tcpRtoMax. More refined
semantics for objects of this type depend upon the algorithm used to determine
the retransmission timeout. In particular, when the timeout algorithm is rsre (3),
an object of this type has the semantics of the UBOUND quantity described in
RFC 793.
Maximum Connections
The limit on the total number of TCP connections the entity can support,
according to the tcpMaxConn. In devices where the maximum numb e r of
connections is dynamic, this object should contain the value -1.
Active Opens
The number of times the TCP connections have made a direct transition to the
SYN-SENT state from the CLOSED state, according to the tcpActiveOpens. Before
TCP can begin transmitting data, applications at both the sending and receiving
applications must agree to form a connection. To form the connection, the sending
application asks TCP for a passive open, which means that it will accept incoming
connections. TCP assigns a port number. The application at the other end then
must contact its operating system (TCP) and request for an active open, which
specifies the IP addresses and port number of the passive open. Once the two
machines agree to set up communication, the first segment sent by the TCP
protocol is the SYNchronizing segment, which synchronizes the two ends of the
connection.
Passive Opens
The number of times the TCP connections have made a direct transition to the
SYN-RCVD state from the LISTEN state, according to the tcpPassiveOpens. Before
TCP can begin transmitting data, applications at both the sending and receiving
applications must agree to form a connection. To form the connection, the sending
application asks TCP for a passive open, which means that it will accept incoming
connections. TCP assigns a port number. The application at the other end then
must contact its operating system (TCP) and request an active open, which
specifies the IP address and port number of the passive open. Once the two
machines agree to set up communication, the first segment sent by the TCP
protocol is the SYNchronizing segment, which synchronizes the two ends of the
connection. The station that receives the SYN-SENT message replies with a
SYN-RCVD message.
Connection Failures
The number of times TCP connections have made a direct transition to the
CLOSED state from either the SYN-SENT state or the SYN-RCVD state and the
number of times the TCP connections have made a direct transition to the LISTEN
state from the SYN-RCVD state. This field displays the tcpAttemptFails.