Ftp Session Control; Protocol Buffer Engineering - Nortel DMS-100 User Manual

cause TCP to drop the existing connections, which could cause a temporary
outage of all TCP applications.

FTP session control

Similar to the concept of TCP numbers, FTP sessions (client and server) on
each node are managed by the parameters FTPSVCON and FTPCLCON in
table IPHOST. These parameters control the number of FTP server and client
sessions allowed on a particular node.
There is no maximum limit defined for these numbers, but they are governed
by the number of TCP connections allowed on the node. Since each FTP
session consumes two TCP connections (control and data), the total number of
FTP client and server sessions taken together cannot exceed half the number
of TCP connections allowed on that node. This restriction obviously does not
take into account other TCP applications on the node. The operating company
must ensure that the values in datafill are adequate for all other TCP
applications (telnet, MDR7, ROSP, and so on).
The number of FTP server and client sessions are tightly coupled with the
number of server and client processes respectively. Each server and client
process manages one FTP server/client session. The number of FTP server
sessions also restricts the number of server processes that can be reserved by
the applications for security reasons. The total number of servers that can be
reserved by different applications cannot exceed the number of servers allowed
on the node.
If the number of client and server sessions for a node in table IPHOST is
modified, the existing sessions are dropped immediately and the FTP client
users are duly notified. FTP layer remains out of service until all the resources
are reallocated to conform to the new datafill. If the number of FTP server and
client sessions is datafilled as zero, FTP cannot provide its services.
This functionality must be exercised cautiously since it causes FTP to drop the
existing sessions, which could cause a temporary outage of all FTP clients and
servers. Similar consequences are observed if the IP address of the node is
modified while the node is in service. Reducing the number of FTP servers
removes defined owner and userID information as necessary. It is up to the user
or application to restore the information when the number of sessions is
increased.

Protocol buffer engineering

The buffer engineering for receiving and transmitting IP packets is a critical
part of the buffer management for the protocol stack. A default number of
buffers is allocated for IP receive and transmit purposes. The buffers are
divided into three categories:
• small (128 bytes)
Chapter 2: EIU messaging protocols 63
DMS-100 Family EIU User Guide TELECOM12