Expand Configuration and Management Manual (G06.24+)

Subsystem Description
Expand Configuration and Management Manual—523347-008
18-39
Outgoing Traffic Flow
Locally Originated Traffic Flow
Figure 18-12 illustrates the path of a locally originated outgoing message.
When a process creates a message that is destined for a remote node, the message
system uses the NRT to route the message to the Expand line-handler process that
can most efficiently transmit the message to the destination node.
When the Expand line-handler process acquires an outgoing message from the
message system, it queues the message to its list of pending outgoing messages for
the appropriate destination node. The Expand line-handler process maintains a
different pending outgoing messages list for each destination node.
The Expand line-handler process checks the security of messages that have the
security bit set. The file system sets the security bit (LSECUREB) on certain requests
such as OPENs. Checking the security of a message involves obtaining the remote
password from the USERID file and attaching it to the outgoing message. If no remote
Figure 18-12. Flow of an Outgoing Local Message
020CDT .CDD
* Security processing
* Data compression
* Message prioritization
Queue message to
pending list for
destination node
Use memory from buffer
pool and queue message
to outgoing message list
Select highest priority
message and format
packets
Send packets
Queue message to wait
for end-to-end ACK list
Queue message
to wait for reply list
Release buffer
pool
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