Data Sheet

Ethernet Controller I210 —System Manageability
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Note: In both SMBus ARP and MCTP, the spec indicates that PEC must be used. However, if PEC is
not used by the master, the transaction is still accepted and processed by the device.
The PEC behavior is controlled by the SMBus transaction PEC bit in the SMBus Notification Timeout and
Flags Flash word: If this bit is set, PEC is added for master SMBus write transactions. a PEC is added to
slave read transactions and can be received in slave write transaction. If this bit is cleared, PEC is not
added to master write or slave read transactions, a slave write transaction with PEC is dropped. This bit
should be set for MCTP mode and should be cleared in legacy SMBus mode.
10.2.1.2 NC-SI
The I210 uses the DMTF standard Sideband Interface. This interface consists of 6 lines for transmission
and reception of Ethernet packets and two optional lines for arbitration among more than one physical
network controller.
The physical layer of NC-SI is very similar to the RMII interface, although not an exact duplicate. Refer
to the NC-SI specification for details of the differences.
10.2.1.3 PCIe
The I210 uses the VDMs (Vendor Defined Messages) over PCIe defined in the DMTF MCTP spec to
convey pass through traffic or NC-SI control traffic. See Section 3.1 for details of the PCIe interface.
The maximal bandwidth supported for MCTP VDMs over PCIe is 250 Mbps. VDMs that will be received at
a faster rate may be dropped. In any case, there will be no back pressure of the PCIe interface due to
MCTP VDM handling.
Slave Write
3
Disabled
(A) Target will ack last data
byte; PEC byte will be 0xFF
(A) Target will nack last data
byte and will generate Stop
after that
Slave Read
4
Enabled
(A) Target will send PEC byte;
PEC byte will be acked by
Slave
(A) Target will not send PEC
byte and will generate Stop
after that
Slave Read
4
Disabled
(R) Target will send PEC byte;
PEC byte will be nacked by
Slave
(A) Target will not send PEC
byte and will generate Stop
after that
1. (A) - Accept Transaction (R) - Reject Transaction.
2. Used in Legacy SMBus writes commands (Direct receive) and in MCTP over SMBus (Transmitted transactions.
3. Used in Legacy SMBus Read commands.
4. Used in Legacy SMBus mode (Alert/Async-Notify) and in MCTP over SMBus (Received transactions).
Table 10-1. SMBus PEC Modes
1
Target PEC Mode
SMBus transaction
(relative to the I210)
I210 PEC Mode PEC Enabled PEC Disabled