16 NETernity* RM921N / RM921ND Hardware Reference Manual
Publication No. 597-0000000013-000 Rev. F
3 •
Theory of Operation
The
RM921N is a VME‐based managed Ethernet switch with 12/24 port Gigabit,
Layer 2/3, supporting IPv6. Moreover, the RM921N supports 100Base-FX interfaces
through different hardware configurations. The management entity executes on an
embedded processor. With a single slot solution, the baseboard supports 12 ports for
GbE or 100Base-FX or a combination of both. With a dual slot solution, the combined
baseboard and expansion board will support a total of 24 ports for GbE, 100Base-FX
or a combination of both.
3.1 Operation
The RM921N block diagram is shown in
. The design incorporates a highly
integrated 24-
port GbE multi‐layer switch fabric. The switch fab
ric supports IPv6
routing functions.
The Management processor configures and manages both the switch and port
controllers.
The DA921 management board with secure memory option provides a Mini Edge
Card socket. This connector enables user to plug/remove the flash memory module
into/from the management board.
The RM921N board supports a combination of fiber and copper media interfaces.
For copper media, the BCM56302 interfaces with an external PHY to provide link
layer support (e.g., auto negotiation). The copper physical interface uses dual RJ45
connectors with integrated LEDs. The fiber optic interface is connected directly to
the switch fabric.