82598EB Datasheet, PDF (530/596 Pages) Intel Corporation – Intel® 82598EB 10 Gigabit Ethernet Controller Datasheet

Intel^® 82598EB 10 GbE Controller - Advanced Workflows
5.4.5 Advanced Workflows
5.4.5.1 Multi-NC Arbitration
As described in Section 5.4.1.2, in a multi-NC environment, there is a need to arbitrate the NC-SI lines.
Figure 5-15 shows the system topology of such an environment.
Figure 5-15. Multi-NC Environment
See Figure 5-15. The NC-SI Rx lines are shared between the NCs. To enable sharing of the NC-SI Rx
lines, NC-SI has defined an arbitration scheme.
The arbitration scheme mandates that only one NC package can use the NC-SI Rx lines at any given
time. The NC package that is allowed to use these lines is defined as selected. All the other NC
packages are de-selected.
NC-SI has defined two mechanisms for the arbitration scheme:
1. Package Selection by the MC. In this mechanism, the MC is responsible for arbitrating between the
packages by issuing NC-SI commands (Select/De-Select Package). The MC is responsible for having
only one package selected at any given time.
2. HW Arbitration. In this mechanism, two additional pins on each NC package are used to synchronize
the NC package. Each NC package has an ARB_IN and ARB_OUT line and these lines are used to
transfer Tokens. A NC package that has a token is considered selected.
Note: Hardware arbitration is enabled by default after interface power-up.
82598EB does not support hardware arbitration.
For further details, refer to section 4 in the NC-SI specification.
5.4.5.1.1 Package Selection Sequence Example
Following is an example work flow for a MC and occurs after the discovery, initialization, and
configuration.
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