Avaya Configuring IP Utilities Uživatelský manuál stáhnout pdf (Strana 42)

Configuring IP Utilities

2-4

304234-A Rev 00

Connection Types

TCP is a connection-oriented protocol that requires application programs at both

ends of a connection to agree to it before TCP traffic can pass across a network. To

do so, the application program at one end performs a passive open while the

application program at the other end performs an active open. For passive opens, a

TCP client (the process or application program that uses TCP) waits to accept

incoming connection requests. Clients using passive opens can listen for specific

connection requests or for a range of inbound requests. In an active open, the

client initiates the connection. Once a connection has been created, application

programs can begin to pass data; that is, the programs at each end exchange

messages that guarantee reliable delivery.

Connections and Connection States

TCP establishes a set of access points, referred to as ports, for each host. It

associates each port with a network and host address to form a socket. A pair of

sockets, together with sequence numbers, window sizes, and status information,

form a TCP connection.

Table 2-2 lists the states through which a TCP connection proceeds during its

lifetime.

Table 2-2. TCP Connection States

State Definition

LISTEN (2) TCP listens for a connection request from any remote TCP.

SYN SENT (3) TCP has sent a connection request (SYN segment) and waits for

a matching connection request and acknowledgment from the

remote TCP.

SYNRECEIVED (4) TCP has sent a connection request, received a matching

request, and waits for a confirming connection request

acknowledgment from the remote TCP.

ESTABLISHED (5) Connection open. Data can be received and sent. This is the

normal state for the data transfer phase of the connection.

FINWAIT-1 (6) TCP waits for a connection termination request (FIN segment)

from the remote TCP, or for an acknowledgment of a previously

sent connection termination request.

(continued)

1 2 ... 37 38 39 40 41 42 43 44 45 46 47 ... 227 228

Žádné komentáře

Avaya Configuring IP Utilities Uživatelský manuál Strana 42