Data Sheet

System Manageability—Ethernet Controller I210
753
10.6.8 Advanced Workflows
10.6.8.1 Multi-NC Arbitration
As described in Section 10.6.1.2, in a multi-NC environment, there is a need to arbitrate the NC-SI
lines.
Figure 10-7 shows the system topology of such an environment.
See Figure 10-7. 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 BMC. In this mechanism, the BMC is responsible for arbitrating between
the packages by issuing NC-SI commands (Select/De-Select Package). The BMC is responsible for
having only one package selected at any given time.
2. Hardware 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 the NC-SI ARB Enable Flash bit (See Section 6.2.22) and
the NC-SI HW arbitration support Flash bit (see Section 6.8.5.7).
For details on Hardware arbitration, refer to the NC-SI specification.
Figure 10-7. Multi-NC Environment
NC Package1
Channel1: 0x0
Channel2: 0x1
NC Package2
Channel1: 0x0
MC
NC-SI TX lines
HW-Arbitration lines
NC-SI RX lines