User's Manual

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4.9.1 Auto-Negotiation
MDR-8000E auto-negotiation is not a stand-alone function, and proper operation and use
of all available functions depends on the capabilities of the external customer equipment
that is connected to the radio. Just because an autonegotiation function is checked for pro
-
visioning does not automatically mean that function is fully operable. The device on the
other end of the cable must also have the capability and be provisioned with a matching
function.
4.9.1.1 Auto-Negotiate
Auto-Negotiate details are beyond the scope of this supplement. The rule of thumb to fol-
low when unsure of what functions to check or change from factory default provisioning is
leave at default (all autonegotiation functions are checked). Full autonegotiation capability
is becoming standard for manufacturers of Ethernet devices.
4.9.1.2 Allow 10, 100, and/or 1000 Mb Half and Full Duplex
If in doubt as to the link speed and mode of the external device connecting Ethernet to the
radio, check all boxes for speeds and modes. If you know the external Ethernet device has
speed and/or mode limitations, check only the boxes that apply.
Auto-Negotiate is automatically enabled when Allow 1000 Mb Full Duplex is enabled.
Auto-Negotiate must be enabled (checked) when more than one link speed is selected.
4.9.1.3 Input/Output Flow Control Features
Checking the box next to Input/Output Flow Control enables input and output pause func-
tions and the forward errored or large frame function. These flow control functions are
described in the following paragraphs.
4.9.1.3.1 Input Pause Feature
See Figure 4 - 16. This feature makes the auto-negotiation function willing to stop receiving
traffic. When the radio input buffers approach overflow, the function sends a pause mes-
sage to the link partner that is transmitting data to the radio, telling the device to tempo-
rarily stop sending data. The link partner will stop sending data if the device has and is
provisioned with the Allow Option Pause function.
If the link partner is either not equipped with or is not provisioned for input pause, data
overflowing the registers in the radio will be lost, regardless of the provisioning for input
pause in the radio. Any time there is an overflow, the radio will alarm and indicate
Dropped Frames on the Performance Monitor screens.
4.9.1.3.2 Pause Feature
This feature auto-negotiation function willing to stop sending traffic. When the input buff-
ers on the link partner approach overflow, the link partner sends a pause message to the
radio telling the radio to temporarily stop sending data. If the Input/Output Flow Control
function is checked, the radio will stop sending out data.