VSC7440 datasheet(68/444 Pages) MICROSEMI

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Functional Descriptions

VMDS-10492 VSC7440 Datasheet Revision 4.2

By default, an Ethernet port does not need configuration in the assembler as long as special settings are

not required. However, the following exceptions may apply:

If the port is used as a stacking port, set ASM::PORT_CFG.VSTAX2_AWR_ENA, which enables

detection of the VStaX stacking header. If a VStaX stacking header is found, the assembler will remove

the header from the frame and put it into the internal frame header.

Frames received from the port modules are preamble prepended by default. If a port module is

configured for preamble shrink mode, the ASM::PORT_CFG.NO_PREAMBLE_ENA must be set to 1,

because the port module does not prepend a preamble in this mode.

When ASM::PORT_CFG.PAD_ENA is set, frames that are smaller than 64 bytes are padded to reach the

minimum frame size.

The assembler has a built-in frame fragment detection mechanism for incoming frames that were started

but never received their EOF (because the port module was taken down, for example). These frames are

normally finalized by creating an EOF abort marked cell. If a frame has been discarded, it is noted in

ASM::PORT_STICKY.FRM_AGING_STICKY. The following table lists the port status register.

3.11.2

Setting Up a Port for Frame Injection

Any front port and the internal CPU ports (ports 11-12) can be configured for frame injection. Frames that

are to be injected must have an IFH prepended the frame data. Optionally, the frame can further be

prepended an SMAC, a DMAC, and a VLAN tag. This results in the following three prefix formats for

injection frames:

•

Injection with long prefix

•

Injection with short prefix

•

Injection with no prefix

The injection format is selected in ASM::PORT_CFG.INJ_FORMAT_CFG. The prefix formats are shown

in the following illustration.

ASM::PORT_CFG.PAD_ENA

Enable padding.

Per port

ASM::PORT_CFG.INJ_DISCARD_CFG

Configures discard behavior for injected frames.

Per port

ASM::PORT_CFG.INJ_FORMAT_CFG

Configure format of injected frames.

Per port

ASM::PORT_CFG.VSTAX2_AWR_ENA

Enable VStaX stacking header awareness.

Per port

Table 31 •

Port Status Register Overview

Target::Register.Field

Description

Replication

ASM::PORT_STICKY.IFH_PREFIX_ERR_STICKY Injection format mismatch sticky bit Per port

ASM::PORT_STICKY.FRM_AGING_STICKY

Frame aging sticky bit

Per port

Table 30 •

Port Configuration Register Overview (continued)

Target::Register.Field

Description

Replication

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