Expand Configuration and Management Manual (H06.21+, J06.10+)

Subsystem Description
Expand Configuration and Management Manual — 529522-013
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Expand-over-IP Connection Establishment
Each NonStop TCP/IP process appears to an IP network as a separate host and is
associated with a separate IP address. An IP address is a 4-octet (32-bit) numeric
value identifying a particular network (network address portion) and a local host on that
network (local address portion). A NonStop TCP/IP process can be associated with
more than one IP address. There can also be more than one NonStop TCP/IP process
on the system at any one time; each process acts as a separate NonStop TCP/IP host.
NonStop TCP/IPv6 provide a feature called single IP which allows a single TCP6SAM
process to act as a single host for all 16 processors. NonStop TCP/IPv6 also provides
the option of using IP version 6 (IPv6) communications. IPv6 provides several new
networking features and a longer, 128-bit IP address.
Both TCP and UDP use a 16-bit port number to select a socket on the host. TCP and
UDP add to IP the capability of having several simultaneous sessions with a given
host. Multiple sessions are accommodated by specifying a port number, which
identifies the communications path, along with the IP address. Each end of the
communications path is assigned a port number for that session.
Expand-over-IP line-handler processes perform addressing by specifying a unique
combination of a destination IP address, destination port number, source IP address,
and source port number.
Expand-over-IP Connection Establishment
When the system is started up, the Expand-over-IP line-handler process waits for the
NonStop TCP/IP or TCP6SAM process (with which it is associated) and the QIO
Monitor process (QIOMON) to start. These processes must be running before Expand-
over-IP lines can be started. Next, the Expand-over-IP line-handler process binds to its
associated NonStop TCP/IP or TCP6SAM process.
After the Expand-over-IP line-handler process has successfully bound to the NonStop
TCP/IP or TCP6SAM process, it tries to establish a connection to the remote Expand-
over-IP line-handler process. There are two ways the Expand-over-IP line-handler
process can attempt to establish a connection: active connect or passive connect.
The default connect method is active connect. Y
ou can cause the Expand-over-IP line-
handler process to use the active connect method by specifying the
CONNECTTYPE_ACTIVEANDPASSIVE modifier.
Active Connect Request
When the Expand-over-IP line-handler process issues an active connect request, it
tries to initiate a connection by sending a Connect Command frame to the remote
Expand-over-IP line-handler process.
When the remote Expand-over-IP line-handler process receives the Connect
Command frame, it responds with a Connect Response frame. When the response is
Note. Because UDP is a connectionless protocol, there is no actual connection to the remote
Expand-over-IP line-handler process.