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Probe packets and settings
AFT and ALB teams use probe packets. Probes are packets (type 886D, either multicast or broadcast) passed over the network between team members. They allow the Intel® Advanced Network Services software to test the member's status. They do add a minor amount of traffic to the network. We recommend turning them off in near capacity networks.
- AFT teams: Probes enabled, broadcast probes used by default
- ALB/RLB teams: Probes enabled, broadcast probes used by default
- SFT teams: Probes disabled
- SLA, 802.3AD teams: No probes used, probe the settings not present in the Advanced Settings page of the team
- Probe (ProbeEnable): Provides the capability to turn probe packets on or off.
- Packet Type: Broadcast or multicast
- CheckTime: Sets the time to wait for a probe.
- Max Number of Probe Retries: Number of times the probe resends unanswered before setting the non-responding adapter to disabled.
- ProbeSendTime: (only some OS) Length of time between probe sends. Based on the tick_frequency. For example, if tick_frequency is 50 milliseconds and the probe interval is 1 second, then ProbeSendTime is 20.
|Changing any of these Advanced Settings also changes the amount of time for failover.
Mechanism of the probe for determining valid team members and primary adapter.
At each probe interval, each adapter in the team sends a probe packet to all other adapters in the team. The probe destination address is a multicast address. It downloads to the underlying member adapters during initialization, so only one packet sends. These packets forward across the PCI bus to the upper layers, but will only be received by adapters registered with this address. In addition, probe packets don't pass through unregistered routers or any router that is blocking the packet type. This transfer is commonly done with broadcast packets.
If you enable probe sends:
- After the ProbeSendTime interval, all adapters in the team send probe packets periodically at the same time. Broadcast or multicast probes send these probes to other adapters in the team.
- If an adapter fails to send or report receiving valid probes after the set timeout period, the system considers it disabled. If the primary adapter fails, the secondary adapter is the failover.
- If the probe packets don't reach their destination before the ProbeCheckTimeout, you can use retries before disabling the destination adapter (ProbeMaxRetryCount).
As long as they are not in the primary or secondary roles, you can mark adapters disabled without changing their roles. However, if the system considers a primary or secondary adapter disabled, a failover is required. The check for a better adapter is made once during each failover cycle. Settings or conditions may apply that make an adapter other than the current primary the best adapter for the primary role. (Enabled adapters are obviously preferred over a disabled adapter.)
|If the base driver is resetting, the probe sends do not succeed causing an immediate failover.
Other methods to detect failover
Probes might turn off for multiple reasons:
- To avoid repeated failovers caused by too much network latency,
- To minimize network traffic, or
- Because of a router or other device blocking broadcasts or this packet type.
With probes off, there are two other methods to monitor team member state:
- Link-Based: Monitoring actual link to partner port per adapter.
- Activity-Based: Monitoring activity on the wire to determine which has the most traffic.
Failback and the role of the preferred primary
After failover occurs, the primary adapter returns to active status. Failback returns the primary role to the preferred primary adapter. Failback only occurs when you set the preferred primary adapter manually. If you set the primary with software, failback does not occur.
Other advanced settings for teaming
- Load Balance Refresh Rate/Balance Interval: The interval between software checks of current load balance and determining rebalance.
- Number RX packets/NumTXPackets: The adjustment to memory use, similar to setting descriptors and buffers. Increasing values may increase throughput, but uses up system resources. Adjust individual adapter resources. See appropriate help files for recommendations.
- Locally administered address (LAA): We recommend overriding the team MAC address with middle layer drivers like WLBS/NLB. For dynamic 802.3ad teams, there are settings for the active aggregator.
- LinkAg Join Method: Tells the aggregators how to split teams and which team to make active. Choose max bandwidth (fastest adapters) or max adapters (largest team).