Expand Configuration and Management Manual (G06.24+)

Subsystem Description
Expand Configuration and Management Manual—523347-008
18-43
Incoming Traffic Flow
Out-of-Sequence (OOS) Packets
OOS packets are destined for a process at the local system but are not received in the
same order in which they were sent. For example, if the Expand line-handler process
receives packet 3 before packet 1, it considers packet 3 to be an OOS packet. When
the Expand line-handler process receives an OOS packet, it places the packet in its
OOS buffer.
Figure 18-14. Flow of Incoming Packets
Note. The OOS buffer is used only if the first packet (which contains the message header) is
not received first. If the first packet is received first but subsequent packets are out of
sequence, packets are placed in the buffer pool and the OOS buffer is not used. The OOS
buffer is described in more detail in Line Buffer
on page 18-47.
022CDT .CDD
Use OOS
buffer space
Reserve memory
from buffer pool
for total message
Match reply to
request and place
in request buffer
pool space
Use memory from
buffer pool for
packet
Out-of-sequence
packet Request packet Reply packet
Check OOS buffer
for out-of-
sequence
packets
Route packet to
outgoing
process of local
$NCP
Reassemble message
when all packets
are received
* Decompress data
* Checksum
* Decompress data
* Checksum
* Security processing
Route message
to server and
release buffer
pool space
Route message
to requester and
release buffer
pool space
Requests Replies
$NCP/passthrough
packet