VSC7440 datasheet(264/444 Pages) MICROSEMI

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Functional Descriptions

VMDS-10492 VSC7440 Datasheet Revision 4.2

247

3.26.3

Supported Frame Formats

The rewriter can identify and rewrite both headers and payload of the following frame types.

Ethernet Frames

•

Ethernet link layer DMAC+SMAC

•

Maximum of three VLAN Q-tags (802.1Q, 802.1ad)

•

Payload (IPv4, IPv6, Y.1731 OAM, PTP, and so on)

The analyzer places information in the IFH to help the rewriter with frame identification. The IFH fields,

IFH.DST.ENCAP.W16_POP_CNT and IFH.DST.ENCAP.TYPE_AFTER_POP, are used for this purpose.

3.26.3.1 Maximum Frame Expansion

The rewriter can push 60 bytes into a frame when the IFH is popped and when no other frame pop

operations are done. The frame preamble will occupy 8 of the 60 bytes that can be pushed.

3.26.4

Rewriter Initialization

Rewriter initialization comprises two steps:

•

Set REW::RAM_INIT.RAM_ENA to 1

•

Set REW::RAM_INIT.RAM_INIT to 1

Before the rewriter can be configured, the RAM-based configuration registers must be initialized by

writing a 1 to the above RAM_INIT registers. The RAM_INIT.RAM_INIT register is reset by hardware

when the initialization is complete.

If VCAP_ES0 is enabled, it must be initialized. All of the default port actions in VCAP_ES0 should also be

initialized to ensure proper operation. For more information about initializing VCAP_ES0, see Versatile

Content-Aware Processor (VCAP), page 55.

3.26.5

VCAP_ES0 Lookup

The rewriter performs stage 0 VCAP egress matching (VCAP_ES0) lookups for each frame when

enabled. The following table lists the registers associated with VCAP_ES0 lookup.

VCAP_ES0 lookup is enabled by setting REW::ES0_CTRL.ES0_LU_ENA = 1. Frames destined to the

DEVCPU cannot be rewritten, and there is no VCAP_ES0 lookup for these frames.

All ES0 actions are ignored when VCAP_ES0 is disabled.

There are two ES0 key types: VID and ISDX.

The VID key is always used if:

•

IFH.FWD.ES0_ISDX_KEY_ENA = 0

•

REW::ES0_CTRL.ES0_BY_RLEG = 1 and (IFH.FWD.DST_MODE = L3UC_ROUTING or

IFH.FWD.DST_MODE = L3MC_ROUTING)

•

REW::ES0_CTRL.ES0_BY_RT_FWD = 1 and IFH.DST.ENCAP.RT_FWD = 1.

Table 170 •

ES0 Configuration Registers

Description

Replication

ES0_CTRL.

ES0_LU_ENA

Enables lookup in VCAP_ES0 to control advanced frame modifications.

None

ES0_CTRL.

ES0_BY_RLEG

Enables ES0 router mode lookup when IFH.FWD.DST_MODE indicates

routing.

None

ES0_CTRL.

ES0_BY_RT_FWD

Enables ES0 router mode lookup when IFH.DST.ENCAP.RT_FWD

indicates routing.

None

PORT_CTRL.

ES0_LPORT_NUM

Maps the configuration port to a logical port number to be used by ES0

keys. The port used in the lookup can be Tx-mirrored.

Ports

VSC7440 Datasheet(PDF) 264 Page - Microsemi Corporation

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