Installing and Administering OSI Transport Services

Chapter 1 29
HP OTS/9000 Resources
How HP OTS/9000 Establishes a Connection
How HP OTS/9000 Establishes a
Connection
Establishing a connection between local and remote systems involves the
following:
• Higher-layer applications, such as FTAM and X.400, require address
information and NSAP values. The addresses determine the peer
entity at each layer of the stack. See “Addressing” in the “Resources”
chapter of this manual.
• A user-created application uses the stream /dev/osipi or
/dev/ositpi for primitive requests. The application registers with
OTS using its local address.
• Upon successful registration, the application sends a connect request
to the remote system.
• If the remote is connected through CONS, OTS/9000 looks up its
X.121 address in the OTS configuration and sends a call packet.
• If the system is attached to an 802.3 or FDDI LAN, OTS/9000 uses
the ES-IS protocol to determine the Media Access Control (MAC)
address for the destination NSAP.
• After the remote address is determined, OTS/9000 normally issues
the connect request to establish a connection if the type of network
service used is a Connection-Oriented Network Service (CONS). This
is provided on X.25 networks.
• If another network service type, Connectionless Network Service
(CLNS), is used, it differs only in that there are no network layer
connections established. OTS/9000 provides CLNS over FDDI, IEEE
802.3 LANs and X.25.