1. General Description
The Realtek RTL8370MB is a TQFP176 E-PAD, high-performance 8+2-port Gigabit Ethernet switch. It
integrates 8 low-power Giga-PHYs that support 1000Base-T/100Base-T/10Base-T, and provides two
extra RGMII/MII/TMII/RMII/SGMII/1000Base-X/100Base-FX ports for specific applications. The
RTL8370MB implements all the functions of a high-speed switch system; including SRAM for packet
buffering, non-blocking switch fabric, and internal register management into a single CMOS device. Only
a 25MHz crystal is required; an optional EEPROM is offered for internal register configuration.
The embedded packet storage SRAM in the RTL8370MB features superior memory management
technology to efficiently utilize memory space. The RTL8370MB integrates a 4096-entry look-up table
with a 4-way XOR Hashing algorithm for address searching and learning. The table provides read/write
access from the EEPROM Serial Management Interface (SMI), and each of the entries can be configured
as a static entry. The entry aging time is between 200 and 400 seconds. Eight Filtering Databases are used
to provide Independent VLAN Learning and Shared VLAN Learning (IVL/SVL) functions.
The Extension GMAC1 and Extension GMAC2 of the RTL8370MB implement dual RGMII/MII/TMII/
RMII interfaces for connecting with an external PHY or MAC in specific applications. This interface
could be connected to an external CPU or RISC as 8-port Gigabit Router applications. In router
applications, the RTL8370MB supports Port VID (PVID) for each port to insert a PVID in the VLAN tag

on egress. When using this function, VID information carried in the VLAN tag will be changed to PVID.

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