Dedicated Micros Digital Sprite 2 Setup Manual page 27

Type
The Digital Sprite 2 can be configured for a specific value or it can be set to a
default network setting, for example a WAN connection would automatically set
the speed of the network port to 32Kbytes/second.
This will ensure the speed of the data from the Digital Sprite 2 does not
exceed the speed of the network connection.
The options available are:
• Custom - this will allow the Administrator to select specific values.
• ISDN - This will set the maximum transmission rate to 64KBits/second for
remote network connection via an ISDN link, it will also automatically alter
the transmit image buffers and Ethernet re-transmit timeout.
• WAN - This will set the maximum transmission rate to 256KBits/second,
and automatically alter the transmit image buffers and Ethernet re-transmit
timeout.
• LAN - This will set the maximum transmission rate to 010000KBits/second
for a local network connection, and automatically alter the transmit image
buffers and Ethernet re-transmit timeout.
Max Transmission Rate
This is a read only setting and shows the maximum transmission speed for the
type of network selected.
Note: If Custom is selected in the Type option, it is possible to configure this
setting between 000000 Kbits/s and 100000 Kbits/s.
Transmission Image Buffer
This is a read only setting and shows the buffer size for the network type
selected.
Note: If Custom is selected in the Type option, it is possible to configure this
setting to 1, 2 or 3.
MTU
The MTU (Maximum Transmission Unit) is the largest physical packet size,
measured in bytes, that a network can transmit. Any messages larger than the
MTU are divided into smaller packets before being sent.
Every network has a different MTU, which is set by the Network Administrator.
Ideally, the MTU should be the same as the smallest MTU of all the networks
between your machine and the final destination. If the MTU figure is too large
they will be broken up (fragmented), which slows down transmission speeds,
and in some cases cause a 'Connection to Unit Timed Out' message when
using DM Network Viewing Software.
MTU sizes can vary for each connection and it may be necessary to use trial
and error to find the optimal MTU. Suggested MTU sizes are as follows;
Network Connection
PPP (ISDN/PSTN routers)
Ethernet
PPPoE (PPP over Ethernet, ADSL, Cable)
PPPoA (PPP over ATM, ADSL)
VPN
Dedicated Micros recommend you obtain this information from your Internet
Service Provider who will provide you with the optimal figure.
Warning: Changing the MTU size can have adverse affects on the
transmission speed and operation over the network. Contact your network
administrator for advice on MTU sizes for the network.
Ethernet Re-transmit Timeout
The Ethernet Re-transmit timeout is the time the unit will wait to re-send a
network packet if an acknowledgement is not received. When making a
connection across WAN link, this figure should match the timeout figure for the
router. Your Network Administrator can provide this information.
PPP Selection
The Digital Sprite 2 supports Point to Point Protocol, this menu allows the PPP
settings to be configured.
MTU Size
576
1500 (default)
1458
1458
1350
25