VSC7440 datasheet(137/444 Pages) MICROSEMI

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Functional Descriptions

VMDS-10492 VSC7440 Datasheet Revision 4.2

120

if (clm_action.fwd_type == POP_LBL && IsOam(frame_ptr, csr) &&

(clm_key_fields_mpls.rsv_lbl_pos)) {

// Reserved label used to identify OAM

// Move frame_ptr if reserved MPLS label was skipped by

// ClmKeyFieldsMpls() in key generation prior to VCAP CLM lookup

frame_ptr += 4;

}

if (frame_ptr - frame_ptr_current > 66) {

// Cannot skip >66 bytes per VCAP CLM.

// Set sticky bit and don't skip anything

csr.adv_cl_max_w16_offset_fail_sticky = 1;

frame_ptr

= frame_ptr_current;

frame_type = frame_type_current;

}

if (frame_ptr > 126 ) {

// Cannot skip >126 bytes total.

// Set sticky bit and discard frame

csr.adv_cl_nxt_offset_too_big_sticky = 1;

frame.abort

= true;

}

} // UpdateFramePtrAndType

// ----------------------------------------------------------------------

// ANA_CL: VCAP CLM Frame Pointer and Frame Type Update

// ======================================================================

3.16.2.3 Removing Protocol Layers

The analyzer classifier can instruct the rewriter to remove protocol layers from the frame, that is, to

remove a number of bytes from the start of the frame.

This is achieved by setting the NXT_NORMALIZE action field in the VCAP CLM action. When

NXT_NORMALIZE is set in a VCAP CLM action, then the frame pointer for the next VCAP CLM lookup

(if any) is calculated, and the rewriter is then instructed to remove all bytes up to, but not including, the

position pointed to by the frame pointer.

If multiple VCAP CLM actions have the NXT_NORMALIZE bit set, then the last such action controls the

number of bytes removed by the rewriter.

Note that the rewriter can skip a maximum of 42 bytes, starting at the DMAC of the frame. This

corresponds to an Ethernet header with three VLAN tags and an MPLS stack with three LSEs and a

control word (CW).

3.16.2.4 Miscellaneous VCAP CLM Key Configuration

The analyzer classifier can control some specific fields when generating the VCAP CLM keys. The

following table lists the registers that control the parameters.

Each port can control specific fields in the generated keys:

•

Selects source of DSCP in L3_DSCP key field

(ANA_CL:PORT:ADV_CL_CFG.USE_CL_DSCP_ENA). By default, the DSCP value is taken from

Table 75 •

Miscellaneous VCAP CLM Key Configuration

Description

Replication

ANA_CL:PORT:ADV_CL_CFG Configures L3_DSCP and TCI0 source.

Per port per VCAP

CLM lookup

ANA_CL::CLM_MISC_CTRL

Configures IGR_PORT_MASK_SEL and IGR_PORT_MASK. None

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