SH7710 Datasheet, PDF (753/996 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7700 Series

Section 18 Ethernet Controller (EtherC)
18.4.3 Relay
EtherC has a function to relay frames received from the MII of either MAC-0 or MAC-1 to the
other MAC. When relay is enabled, frames input from the MII are sent to both the TSU FIFO and
receive E-DMAC, and determined independently whether to receive or not by the receive E-
DMAC and whether to relay or not by the TSU. (Refer to figure 18.2.) To execute relay, specify
both MAC controllers as promiscuous mode, and the same MAC address in both MAC controllers
(hereafter this MAC address is referred to as MAC address of this LSI). The setting of the transfer
frame processing (relayed/discarded) is carried by the TSU_FWSL0 and TSU_FWSL1. Frames
passing the TSU FIFO during relaying are sent to the PHY_LSI from MAC-1 in MAC-0 to MAC-
1 relay, from MAC-0 in MAC1 to MAC0 relay via the MII. At this time, collision with the relay
frames from the E-DMAC may occur. The priority of the process when collision occurs can be set
by TSU_PRISL0/1. For multicast frames and frames their destinations are other than this LSI, the
CAM evaluation in frame relay processing can be referenced (for details on the CAM function,
refer to section 18.4.4, CAM Function). Table 18.2 shows the settings of the relay frame
processing (without CAM).
Table 18.2 Transfer Frame Processing (Without CAM)
Name
Frame for this LSI
Broadcast frame
Multicast frame
Frames to destinations other
than this LSI
TSU-FWSL
FW40/1 = 0
FW40/1 = 1
FW30/1 = 0
FW30/1 = 1
FW20/1 = 0
FW20/1 = 1
FW10/1 = 0
FW10/1 = 1
Frame Processing
Discarded
Relayed
Discarded
Relayed
Discarded
Relayed
Discarded
Relayed
18.4.4 CAM Function
Frames input to the MAC are grouped into the following four types; unicast for this LSI,
broadcast, multicast, and unicast to other destinations. Of this, the MAC addresses of unicast for
this LSI and broadcast are fixed, and determination is carried out only by register settings.
Consequently, only multicast and unicast to other destinations determine whether to receive or not
and whether to relay or not by using the CAM (unicast frames whose destination MAC addresses
match this LSI are called unicast frames to this LSI, and those that do not are called unicast frames
to other destinations).
Rev. 2.00 Dec. 07, 2005 Page 711 of 950
REJ09B0079-0200