This parameter can be used to set the flow control capabilities the port reports during auto-negotiation. Possible values are: Sym, SymOrRem, LocSend, or None; SymOrRem is the default. The different modes have the following meaning:

Sym = Symmetric both link partners are allowed to send PAUSE frames

This parameter is valid only for 1000Base-T adapter cards. For two 1000Base-T ports to communicate, one must take the role of the master (providing timing information), while the other must be the slave. Possible values are: Auto, Master, or Slave; Auto is the default. Usually, the role of a port is negotiated between two ports during link establishment, but if that fails the port A of an adapter card can be forced to a specific setting with this parameter.

This parameter is valid only for 1000Base-T adapter cards. For two 1000Base-T ports to communicate, one must take the role of the master (providing timing information), while the other must be the slave. Possible values are: Auto, Master, or Slave; Auto is the default. Usually, the role of a port is negotiated between two ports during link establishment, but if that fails the port B of an adapter card can be forced to a specific setting with this parameter.

This parameter is a combination of all five per-port parameters within one single parameter. This simplifies the configuration of both ports of an adapter card. The different values of this variable reflect the most meaningful combinations of port parameters. Possible values and their corresponding combination of per-port parameters:

Interrupt moderation is employed to limit the maximum number of interrupts the driver has to serve. That is, one or more interrupts (which indicate any transmit or receive packet to be processed) are queued until the driver processes them. When queued interrupts are to be served, is determined by the IntsPerSec parameter, which is explained later below. Possible moderation modes are: None, Static, or Dynamic; None is the default. The different modes have the following meaning:

None No interrupt moderation is applied on the adapter card. Therefore, each transmit or receive interrupt is served immediately as soon as it appears on the interrupt line of the adapter card.

Static Interrupt moderation is applied on the adapter card. All transmit and receive interrupts are queued until a complete moderation interval ends. If such a moderation interval ends, all queued interrupts are processed in one big bunch without any delay. The term Static reflects the fact, that interrupt moderation is always enabled, regardless how much network load is currently passing via a particular interface. In addition, the duration of the moderation interval has a fixed length that never changes while the driver is operational.

Dynamic Interrupt moderation might be applied on the adapter card, depending on the load of the system. If the driver detects that the system load is too high, the driver tries to shield the system against too much network load by enabling interrupt moderation. If—at a later time—the CPU utilization decreases again (or if the network load is negligible), the interrupt moderation will automatically be disabled.

Interrupt moderation should be used when the driver has to handle one or more interfaces with a high network load, which—as a consequence—leads also to a high CPU utilization. When moderation is applied in such high network load situations, CPU load might be reduced by 20–30% on slow computers.

Note that the drawback of using interrupt moderation is an increase of the round-trip-time (RTT), due to the queuing and serving of interrupts at dedicated moderation times.

This parameter determines the length of any interrupt moderation interval. Assuming that static interrupt moderation is to be used, an IntsPerSec parameter value of 2000 will lead to an interrupt moderation interval of 500 microseconds. Possible values for this parameter are in the range of 30...40000 (interrupts per second). The default value is 2000.

This parameter is used only if either static or dynamic interrupt moderation is enabled on a network adapter card. This parameter is ignored if no moderation is applied.

Note that the duration of the moderation interval is to be chosen with care. At first glance, selecting a very long duration (e.g., only 100 interrupts per second) seems to be meaningful, but the increase of packet-processing delay is tremendous. On the other hand, selecting a very short moderation time might compensate the use of any moderation being applied.

This parameter is used to force the preferred port to A or B (on dual-port network adapters). The preferred port is the one that is used if both ports A and B are detected as fully functional. Possible values are: A or B; A is the default.

RLMT monitors the status of the port. If the link of the active port fails, RLMT switches immediately to the standby link. The virtual link is maintained as long as at least one physical link is up. This parameters states how RLMT should monitor both ports. Possible values are: CheckLinkState, CheckLocalPort, CheckSeg, or DualNet; CheckLinkState is the default. The different modes have the following meaning:

CheckLinkState Check link state only: RLMT uses the link state reported by the adapter hardware for each individual port to determine whether a port can be used for all network traffic or not.

CheckLocalPort In this mode, RLMT monitors the network path between the two ports of an adapter by regularly exchanging packets between them. This mode requires a network configuration in which the two ports are able to see each other (i.e., there must not be any router between the ports).

CheckSeg Check local port and segmentation: This mode supports the same functions as the CheckLocalPort mode and additionally checks network segmentation between the ports. Therefore, this mode is to be used only if Gigabit Ethernet switches are installed on the network that have been configured to use the Spanning Tree protocol.

DualNet In this mode, ports A and B are used as separate devices. If you have a dual port adapter, port A will be configured as eth[x] and port B as eth[x+1]. Both ports can be used independently with distinct IP addresses. The preferred port setting is not used. RLMT is turned off.

Note that RLMT modes CheckLocalPort and CheckLinkState are designed to operate in configurations where a network path between the ports on one adapter exists. Moreover, they are not designed to work where adapters are connected back-to-back.