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QMultiFlex-400™ Installation and Operating Handbook
6.2.22.13
Ethernet MTU
Range:
1,000 bytes to 10,240 bytes; step size: 1 byte (Default 1500)
Description:
This controls the Ethernet Maximum Transmission Unit (MTU) size,
which defines the largest Ethernet frame that can be handled by the
modem in bridging mode without fragmentation into smaller frames.
6.2.22.14
M&C MTU
Range:
1,000 bytes to 10,240 bytes; step size: 1 byte (Default 1500)
Description:
This controls the M&C Ethernet Maximum Transmission Unit (MTU) size,
which defines the largest Ethernet frame that can be handled by the
modem M&C port without fragmentation into smaller frames.
6.2.22.15
Terrestrial Buffer Size
Range:
0 to 99999 packets (Default 0)
Description:
The terrestrial buffer is used to buffer IP packets coming into the IP
terrestrial ports for transmission over satellite. Satellite delay and the
quality of the service in general can be controlled by the size of this buffer
in conjunction with setting the size of the satellite buffer. The buffer
should be set large enough to accommodate bursts of packets being
received by the modem. Setting the buffer larger than necessary could
result in large packet delays building up should more packets be sent to
the modem than can be transmitted.
The default value for this buffer is zero, which should be fine for most
situations. The optimal size for the buffer depends on the link data rate,
the packet sizes, the number of packets and the specific application
(some applications being able to tolerate packet loss and/or delays more
than others). When the buffer is full then received packets will be dropped
until space in the buffer is freed up. It is generally desirable for the
terrestrial buffer to be set so that packets are not dropped unnecessarily
before they have been assessed by the traffic shaper as to priority, etc.
At the same time, a large buffer could result in stale data being kept,
which it might be better to drop by making the buffer smaller so that only
the most recent data is kept in an overload situation.
Table 6-42 Ethernet MTU
Table 6-43 M&C MTU
Table 6-44 Terrestrial Buffer Size
6-57
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