Data Sheet
Interconnects—Ethernet Controller I210
103
3.7.5.2 PAUSE and MAC Control Frames Forwarding
Two bits in the Receive Control register, control forwarding of PAUSE and MAC control frames to the
host. These bits are Discard PAUSE Frames (DPF) and Pass MAC Control Frames (PMCF):
•The DPF bit controls forwarding of PAUSE packets to the host.
•The PMCF bit controls forwarding of non-PAUSE packets to the host.
Note: When flow control reception is disabled (CTRL.RFCE = 0b), legacy flow control packets are not
recognized and are parsed as regular packets.
Table 3-26 lists the behavior of the DPF bit.
Table 3-27 defines the behavior of the PMCF bit.
3.7.5.3 Transmission of PAUSE Frames
The I210 generates PAUSE packets to ensure there is enough space in its receive packet buffers to
avoid packet drop. The I210 monitors the fullness of its receive packet buffers and compares it with the
contents of a programmable threshold. When the threshold is reached, the I210 sends a PAUSE frame.
The I210 supports the sending of link Flow Control (FC).
Note: Similar to receiving link flow control packets previously mentioned, link XOFF packets can be
transmitted only if this configuration has been negotiated between the link partners via the
auto-negotiation process or some higher level protocol. The setting of this bit by the software
device driver indicates the desired configuration.
The transmission of flow control frames should only be enabled in full-duplex mode per the
IEEE 802.3 standard. Software should ensure that the transmission of flow control packets is
disabled when the I210 is operating in half-duplex mode.
3.7.5.3.1 Operation and Rules
Transmission of link PAUSE frames is enabled by software writing a 1b to the TFCE bit in the Device
Control register.
Table 3-26. Forwarding of PAUSE Packet to Host (DPF Bit)
RFCE DPF Are FC Packets Forwarded to Host?
0 X Yes if pass the L2 filters (refer to Section 7.1.1.1).
1
1. The flow control multicast address is not part of the L2 filtering unless explicitly required.
10Yes.
11No.
Table 3-27. Transfer of Non-PAUSE Control Packets to Host (PMCF Bit)
RFCE PMCF Are Non-FC MAC Control Packets Forwarded to Host?
0 X Yes if pass the L2 filters (refer to Section 7.1.1.1).
11Yes.
10No.