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 Home > Support > Documents > Driver Options
Advanced Driver Options
Alacritech supports a number of advanced driver options which are described below:
Release 10 Driver Advanced Options
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Option: Fastpath
Registry Variable: Fastpath
Applies to: Release 10 SEN3000 series,
SEN2X00 series
Applies When: TCP connection is offloaded
Default Value: Enabled
Allowed Values: Disabled, Enabled
Description: This is a diagnostic setting that should always be enabled for normal operation. In normal operation, connections that are accepted for offload from chimney are sent to the hardware. If fastpath is disabled then the connections are not sent to the hardware, but handled by the Alacritech miniport driver. Disabling offload will hinder performance, and should only be done for diagnostic purposes at the behest of Alacritech Support personnel.
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Option: 802.3x Flow Control
Registry Variable: *FlowControl
Applies to: Release 10 SEN3000 series
Applies When: Always
Default Value: RX & TX Enabled
Allowed Values: Disabled, RX & TX Enabled, RX Enabled, TX Enabled
Description: This setting activates and deactivates 802.3x flow control. The Alacritech SEN3000 series 10 gigabit Network Accelerator has relatively less buffer memory when compared to Alacritech 1 gigabit cards, therefore it is strongly recommended that flow control is enabled on the SEN3000, as well as on any intervening network hardware. In the absence of flow control, packets may be dropped as throughput approaches maximum bandwidth.
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Option: Framing
Registry Variable: Framing
Applies to: Release 10 SEN3000 series
Applies When: TCP connection is offloaded
Default Value: Enabled
Allowed Values: Disabled, Enabled
Description: This setting controls how the SEN3000 Series handles some well behaved protocols such as CIFS. It should always be enabled during normal operations. It should only be changed at the behest of Alacritech Support.
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Option: Interrupt Moderation
Registry Variable: *InterruptModeration
Applies to: Release 10 SEN3000 series
Applies When: Always
Default Value: Enabled
Allowed Values: Disabled, Enabled
Description: Interrupt moderation is a method by which multiple packets are buffered and then sent or received with a single interrupt. Interrupt moderation is most useful when sending or receiving small packets. Alacritech has chosen timer default values that we believe provide the maximum benefit for most scenarious. Unlike some other network drivers, Alacritech uses the same timer for both send and receive.
It is recommended that the timer settings not be changed except by persons with a high level of networking expertise who have a thorough understanding of interrupt moderation.
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Option: Interrupt Moderation Idle Timeout
Registry Variable: MinModeration
Applies to: Release 10 SEN3000 series
Applies When: Always
Default Value: 16
Allowed Values: 0 - 64
Description: The maximum network idle time in microseconds that the driver will wait with data pending and no new data is received before generating an interrupt. Each new data request will reset this timer. This value should be less than the Interrupt Moderation Maximum Timeout.
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Option: Interrupt Moderation Maximum Timeout
Registry Variable: MaxModeration
Applies to: Release 10 SEN3000 series
Applies When: Always
Default Value: 64
Allowed Values: 0 - 255
Description: The absolute maximum time in microseconds between interrupts with data pending. This value should be greater than the Interrupt Moderation Idle Timeout.
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Option: IPv4 Checksum Offload
Registry Variable: *IPChecksumOffloadIPv4
Applies to: Release 10 SEN3000 series,
SEN2X00 series
Applies When: Connection is in host
Default Value: RX & TX Enabled
Allowed Values: Disabled, RX & TX Enabled, RX Enabled, TX Enabled
Description: Enables stateless offload of IPv4 checksum. This setting has no effect if the entire connection is offloaded.
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Option: Jumbo Packet
Registry Variable: *JumboPacket
Applies to: Release 10 SEN3000 series,
SEN2X00 series
Applies When: Always
Default Value: 1514
Allowed Values: 1514, 9014
Description: Alacritech jumbo packet size references include the default ethernet header plus the MTU, but not the CRC. Technically, we should just state the MTU, as the ethernet header size is not fixed if tagged frames are supported. We should just state the MTU values as 1500 and 9000. ...but we don't. Rest assured that our "jumbo packet" size of 9014 really means an MTU of 9000.
Before enabling this option, make sure that jumbo frames are enabled on all switches between this host and the target host(s).
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Option: Large Send Offload v1 (IPv4)
Registry Variable: *LsoV1IPv4
Applies to: Release 10 SEN3000 series,
SEN2X00 series
Applies When: TCP connection is in host
Default Value: Enabled
Allowed Values: Disabled, Enabled
Description: Allows IPv4 TCP sends to be offloaded to the network card. LSO v1 supports a maximum segment offload size of 64kb. LSO v1 is supported for IPv4 only.
If LSOv1 and LSOv2 are both enabled, LSOv2 will be used.
This setting only applies if the connection is in host. If the connection is offloaded, all TCP is offloaded.
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Option: Large Send Offload v2 (IPv4)
Registry Variable: *LsoV2IPv4
Applies to: Release 10 SEN3000 series,
SEN2X00 series
Applies When: TCP connection is in host
Default Value: Enabled
Allowed Values: Disabled, Enabled
Description: Allows IPv4 TCP sends to be offloaded to the network card. LSO v2 supports a maximum segment offload size of 256kb.
If LSOv1 and LSOv2 are both enabled, LSOv2 will be used.
This setting only applies if the connection is in host. If the connection is offloaded, all TCP is offloaded.
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Option: Large Send Offload v2 (IPv6)
Registry Variable: *LsoV2IPv6
Applies to: Release 10 SEN3000 series
Applies When: TCP connection is in host
Default Value: Enabled
Allowed Values: Disabled, Enabled
Description: Allows IPv6 TCP sends to be offloaded to the network card. LSO v2 supports a maximum segment offload size of 256kb.
This setting only applies if the connection is in host. If the connection is offloaded, all TCP is offloaded.
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Option: Link Speed and Duplex
Registry Variable: *SpeedDuplex
Applies to: Release 10 SEN2X00 series
Default Value: Auto
Applies When: Always
Allowed Values:
Gig Copper: Auto, 1000 Full, 100 Full, 100 Half, 10 Full, 10 Half
Gig Fiber: Auto, 1000 Full
Description: Alacritech strongly recommends that you leave your switch ports set to auto but if your switch is not set to auto, you must change the Alacritech port's link speed and duplex to match the switch setting.
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Option: Receive Side Scaling (RSS)
Registry Variable: *RSS
Applies to: Release 10 SEN3000 series,
SEN2X00 series
Applies When: RSS is globally enabled
Default Value: Enabled
Allowed Values: Disabled, Enabled
Description: Enables or disables Receive Side Scaling on a per port basis. In the traditional Windows network stack, all network interrupts are processed by a single CPU. RSS allows network interrupts to be distributed across multiple CPUs. Whether or not this improves performance or not on Server 2003 is debatable, but on NDIS 6.0 (Vista, Server 2008), RSS definitely helps.
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Option: TCP Checksum Offload (IPv4)
Registry Variable: *TCPChecksumOffloadIPv4
Applies to: Release 10 SEN3000 series,
SEN2X00 series
Applies When: TCP connection is in host.
Default Value: RX & TX Enabled
Allowed Values: Disabled, RX & TX Enabled, RX Enabled, TX Enabled
Description: Allows IPv4 TCP checksums to be computed in hardware rather than by the host stack.
This setting only applies if the connection is in host. If the connection is offloaded, TCP checksums are also offloaded.
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Option: TCP Checksum Offload (IPv6)
Registry Variable: *TCPChecksumOffloadIPv6
Applies to: Release 10 SEN3000 series
Applies When: TCP connection is in host.
Default Value: RX & TX Enabled
Allowed Values: Disabled, RX & TX Enabled, RX Enabled, TX Enabled
Description: Allows IPv6 TCP checksums to be computed in hardware rather than by the host stack.
This setting only applies if the connection is in host. If the connection is offloaded, TCP checksums are also offloaded.
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Option: TCP Connection Offload (IPv4)
Registry Variable: *TCPConnectionOffloadIPv4
Applies to: Release 10 SEN3000 series,
SEN2X00 series
Applies When: TCP Chimney is globally enabled
Default Value: Enabled
Allowed Values: Disabled, Enabled
Description: Allows IPv4 TCP connection offload to be enabled or disabled on a per port basis.
This setting will have no effect if TCP Chimney is globally disabled
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Option: TCP Connection Offload (IPv6)
Registry Variable: *TCPConnectionOffloadIPv6
Applies to: Release 10 SEN3000 series
Applies When: TCP Chimney is globally enabled
Default Value: Enabled
Allowed Values: Disabled, Enabled
Description: Allows IPv6 TCP connection offload to be enabled or disabled on a per port basis.
This setting will have no effect if TCP Chimney is globally disabled
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Release 7 Driver Advanced Options
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Option: Jumbo Frame Size
Applies to: Release 7
Default Value: Disabled
Allowed Values: Disabled (1514), 9014, 16128
Description: Alacritech Ethernet frame size references refer to the ethernet header plus the MTU, but not the CRC. Technically, the actual frame size should include the CRC, so we should have the values listed as (1518), 9018, and 16132, or do like most other vendors and refer to the MTU sizes (1500), 9000, 16114. ...but we don't. Rest assured that our 9014 means an MTU of 9000.
Before enabling this option, make sure that jumbo frames are enabled on all switches between this host and the target host(s). Very few vendors support an MTU of > 9000, so this is the recommended setting if you enable jumbo frames.
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Option: Link Speed and Duplex
Applies to: Release 7
Default Value: Auto
Allowed Values:
Gig Copper: Auto, 1000 Full, 100 Full, 100 Half, 10 Full, 10 Half
Gig Fiber: Auto, 1000 Full
100MB Copper: Auto, 100 Full, 100 Half, 10 Full, 10 Half
Description: Alacritech strongly recommends that you leave your switch ports set to auto but if your switch is not set to auto, you must change the Alacritech port's link speed and duplex to match the switch setting.
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Option: TCP Checksum Offload
Applies to: Release 7
Default Value: Disabled
Allowed Values: Disabled, Enabled
Description: Allows TCP checksums to be computed in hardware rather than by the host stack.
This setting only applies to what we refer to as Dumb NIC mode. This means that the Alacritech TCP Offload (Fast-Path) driver (atcp.sys) is either not installed, or is disabled on this interface. If you are running in dumb NIC mode, you may get better performance by enabling checksum offload.
With TCP Offload enabled, this setting is ignored.
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Option: Large Send Offload
Applies to: Release 7
Default Value: Disabled
Allowed Values: Disabled, Enabled
Description: Also known as segmentation offload, this option allows the host to pass an entire send buffers worth of data to the card even it is larger than the current MTU. The card will then handle splitting it into TCP segments.
This setting only applies to what we refer to as Dumb NIC mode. This means that the Alacritech TCP Offload (Fast-Path) driver (atcp.sys) is either not installed, or is disabled on this interface. If you are running in dumb NIC mode, you may get better performance by enabling large send offload.
With TCP Offload enabled, this setting is ignored.
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Option: Tagged VLAN Identifier
Applies to: Release 7
Default Value: 1
Allowed Values: 1 - 4094
Description: Alacritech only supports membership in a single tagged VLAN. This value is the identifier for that VLAN.
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Option: VLAN Tagging
Applies to: Release 7
Default Value: Disabled
Allowed Values: Disabled, Enabled
Description: Allows membership in a single tagged VLAN.
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Release 9.2.x.x Driver Advanced Options
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Option: IPv4 Checksum Offload
Applies to: Release 9
Default Value: RX & TX Enabled
Allowed Values: Disabled, RX & TX Enabled, RX Enabled, TX Enabled
Description: Allows IPv4 checksums to be computed in hardware rather than by the host stack.
This setting only applies if the connection is in host. If the connection is offloaded, IPv4 checksums are also offloaded.
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Option: Jumbo Packet Size
Applies to: Release 9.1 and later
Default Value: 1514
Allowed Values: 1514, 9014
Description: Alacritech jumbo packet size references include the default ethernet header plus the MTU, but not the CRC. Technically, we should just state the MTU, as the ethernet header size is not fixed if tagged frames are supported. We should just state the MTU values as 1500 and 9000. ...but we don't. Rest assured that our "jumbo packet" size of 9014 really means an MTU of 9000.
Before enabling this option, make sure that jumbo frames are enabled on all switches between this host and the target host(s).
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Option: Link Speed and Duplex
Applies to: Release 9
Default Value: Auto
Allowed Values:
Gig Copper: Auto, 1000 Full, 100 Full, 100 Half, 10 Full, 10 Half
Gig Fiber: Auto, 1000 Full
Description: Alacritech strongly recommends that you leave your switch ports set to auto but if your switch is not set to auto, you must change the Alacritech port's link speed and duplex to match the switch setting.
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Option: Receive Side Scaling
Applies to: Release 9.2
Default Value: Enabled
Allowed Values: Disabled, Enabled
Description: Enables or disables Receive Side Scaling
In the traditional Windows network stack, all network interrupts are processed by a single CPU. RSS allows network interrupts to be distributed across multiple CPUs. Whether or not this improves performance or not on Server 2003 is debatable.
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Option: TCP Checksum Offload (IPv4)
Applies to: Release 9
Default Value: RX & TX Enabled
Allowed Values: Disabled, RX & TX Enabled, RX Enabled, TX Enabled
Description: Allows TCP checksums to be computed in hardware rather than by the host stack.
This setting only applies if the connection is in host. If the connection is offloaded, TCP checksums are also offloaded.
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Option: TCP Large Send Offload (v1)
Applies to: Release 9.2
Default Value: Enabled
Allowed Values: Disabled, Enabled
Description: Allows large TCP sends to be offloaded to the network card.
This setting only applies if the connection is in host. If the connection is offloaded, all TCP is offloaded.
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9.3.x.x Driver Advanced Options
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Option: IPv4 Checksum Offload
Applies to: Release 9
Default Value: RX & TX Enabled
Allowed Values: Disabled, RX & TX Enabled, RX Enabled, TX Enabled
Description: Allows IPv4 checksums to be computed in hardware rather than by the host stack.
This setting only applies if the connection is in host. If the connection is offloaded, IPv4 checksums are also offloaded.
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Option: Jumbo Packet Size
Applies to: Release 9.1 and later
Default Value: 1514
Allowed Values: 1514, 9014
Description: Alacritech jumbo packet size references include the default ethernet header plus the MTU, but not the CRC. Technically, we should just state the MTU, as the ethernet header size is not fixed if tagged frames are supported. We should just state the MTU values as 1500 and 9000. ...but we don't. Rest assured that our "jumbo packet" size of 9014 really means an MTU of 9000.
Before enabling this option, make sure that jumbo frames are enabled on all switches between this host and the target host(s).
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Option: Link Speed and Duplex
Applies to: Release 9
Default Value: Auto
Allowed Values:
Gig Copper: Auto, 1000 Full, 100 Full, 100 Half, 10 Full, 10 Half
Gig Fiber: Auto, 1000 Full
Description: Alacritech strongly recommends that you leave your switch ports set to auto but if your switch is not set to auto, you must change the Alacritech port's link speed and duplex to match the switch setting.
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Option: Receive Side Scaling
Applies to: Release 9.2 and later
Default Value: Enabled
Allowed Values: Disabled, Enabled
Description: Enables or disables Receive Side Scaling
In the traditional Windows network stack, all network interrupts are processed by a single CPU. RSS allows network interrupts to be distributed across multiple CPUs. Whether or not this improves performance or not on Server 2003 is debatable.
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Option: TCP Checksum Offload (IPv4)
Applies to: Release 9
Default Value: RX & TX Enabled
Allowed Values: Disabled, RX & TX Enabled, RX Enabled, TX Enabled
Description: Allows TCP checksums to be computed in hardware rather than by the host stack.
This setting only applies if the connection is in host. If the connection is offloaded, TCP checksums are also offloaded.
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Option: TCP Large Send Offload (v1)
Applies to: Release 9.2 and later
Default Value: Enabled
Allowed Values: Disabled, Enabled
Description: Allows large TCP sends to be offloaded to the network card. LSO v1 supports a maximum segment offload size of 64kb
LSO v1 is supported for IPv4 only. This setting only applies if the connection is in host. If the connection is offloaded, all TCP is offloaded.
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Option: TCP Large Send Offload (v2)
Applies to: Release 9.3
Default Value: Enabled
Allowed Values: Disabled, Enabled
Description: Allows large TCP sends to be offloaded to the network card. LSO v2 supports a maximum segment offload size of 256kb.
LSO v2 is supported for IPv4 only. This setting only applies if the connection is in host. If the connection is offloaded, all TCP is offloaded.
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Release 9.1.x.x Driver Advanced Options
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Option: Jumbo Frame Size
Applies to: Release 9.1 and later
Default Value: 1514
Allowed Values: 1514, 9014
Description: Alacritech jumbo packet size references include the default ethernet header plus the MTU, but not the CRC. Technically, we should just state the MTU, as the ethernet header size is not fixed if tagged frames are supported. We should just state the MTU values as 1500 and 9000. ...but we don't. Rest assured that our "jumbo packet" size of 9014 really means an MTU of 9000.
Before enabling this option, make sure that jumbo frames are enabled on all switches between this host and the target host(s).
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Option: Link Speed and Duplex
Applies to: Release 9
Default Value: Auto
Allowed Values:
Gig Copper: Auto, 1000 Full, 100 Full, 100 Half, 10 Full, 10 Half
Gig Fiber: Auto, 1000 Full
Description: Alacritech strongly recommends that you leave your switch ports set to auto but if your switch is not set to auto, you must change the Alacritech port's link speed and duplex to match the switch setting.
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Option: TCP Checksum Offload
Applies to: Release 9
Default Value: Enabled
Allowed Values: Disabled, Enabled
Description: Allows TCP checksums to be computed in hardware rather than by the host stack.
This setting only applies if the connection is in host. If the connection is offloaded, TCP checksums are also offloaded.
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Option: TCP Offload
Applies to: Release 9
Default Value: Enabled
Allowed Values: Disabled, Enabled
Description: Allows TCP traffic to be offloaded to hardware. This setting should only be disabled for diagnostic purposes. This setting replaces the "Alacritech TCP fastpath driver" setting in the network interface properties pane on the older non-SNP aware Alacritech drivers.
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