Axel AX3000 80 User Manual

Appendix
AX3000 Models 80 and 85 - User's Manual 203
Notes:
- The available parameters depend on both the connection type (screen or auxiliary port) and
the associated protocol.
- New values are used for the next TCP/IP connection (no need to power-cycle the AX3000).
a) 'Secondary Server' Parameter
A secondary server allows the user to select on which server the session is connected to. The
server is chosen when the session is established. A mini-menu is displayed.
b) 'TCP port' Parameter
This parameter is the server TCP port on which the session is connected. The default value
depends on the current protocol.
c) 'mss' and 'Window' Parameters
These two parameters are the AX3000 resources allocated to telnet and tty screen sessions for
receiving network data:
- mss (maximum segment size) is the largest segment of TCP data. This size is negotiated
with the server at the connection time.
- window is the reception windows size (i.e. the size of the buffer on which the TCP data is
stored.
It is not advisable to modify these two values unless the input data flow is not continuous (i.e. the
data flow pauses and resumes regularly during scrolling).
d) 'Time to Live' Parameter
This parameter controls the ‘to live’ time of the datagram to prevent it being looped forever due to
routing errors. Routers decrement the TTL of every datagram as it traverses from one network to
another. When its value reaches 0 the packet is dropped.
This parameter doesn't impact the AX3000 performance.
e) 'TCP port Assignment' Parameter
The AX3000 resources (screen sessions and auxiliary ports) are identified by numeric values called
TCP ports.
The TCP port assignment can be either random or fixed. The default value depends on the current
network service.
The random method means the AX3000 TCP ports are different after every re-boot. On booting the
AX3000 generates a new base value. This value (x) is between 1024 and 3072. For each session a
range of 8 TCP ports is given: session 1 = (x...x+7), session 2 = (x+8…x+15)... When a connection
is established the next port of the associated range is used. After 8 connections, the same TCP
port of a range is re-used.
The main benefit of this method is that if the AX3000 is suddenly powered off (power cut for
example), at the next boot time, the connections are immediately accepted by the server. (i.e. the
sessions are hooked on different sockets because the TCP ports are different). However this does
create ‘phantom’ sessions, as the initial sessions are still active from the server’s perspective, and
must be killed by the server.
This can be done with the ‘keepalive’ process, manually killing or rebooting.
In some situations it may be beneficial to have always the same TCP port for an AX3000 resource

Axel AX3000 80 Specifications

General

Brand	Axel
Model	AX3000 80
Category	Server
Language	English