VSC7440 datasheet(140/444 Pages) MICROSEMI

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Functional Descriptions

VMDS-10492 VSC7440 Datasheet Revision 4.2

123

256 rows the QoS mapping starts at and the MAP_KEY defines which parameter from the frame to use

as key into the QoS mapping table. The following lists the available keys and how the resulting row and

entry number in the mapping table is derived:

•

PCP. Use PCP from the frame’s outer VLAN tag. If the frame is untagged, the port’s VLAN tag is

used. Row and entry number is derived the following way:

Row = MAP_IDX, Entry = PCP.

Number of entries per mapping: 8 entries.

•

DEI and PCP. Use DEI and PCP from one of the frame’s VLAN tags. The MAP_KEY can select

between using either outer, middle, or inner tag. If the frame is untagged, the port’s VLAN tag is

used. Row and entry number is derived the following way:

Row = (8x DEI + PCP) DIV 8 + MAP_IDX, Entry = (8x DEI + PCP) MOD 8.

Number of entries per mapping: 16 entries.

•

DSCP (IP frames only). Use the frame’s DSCP value. For non-IP frames, no mapping is done. Row

and entry number is derived the following way:

Row = DSCP DIV 8 + MAP_IDX, Entry = DSCP MOD 8.

Number of entries per mapping: 64 entries.

•

DSCP (all frames). Use the frame’s DSCP value. For non-IP VLAN tagged frames, use DEI and

PCP from the frame’s outer VLAN tag. For non-IP untagged frames, use DEI and PCP from port

VLAN. Row and entry number is derived the following way:

IP frames:

Row = DSCP DIV 8 + MAP_IDX, Entry = DSCP MOD 8.

Non-IP frames:

Row = (8x DEI + PCP) DIV 8 + MAP_IDX + 8, Entry = (8x DEI + PCP) MOD 8.

Number of entries per mapping: 80 entries.

•

TC. Use the frame’s classified TC bits from the extracted MPLS label (label selected by VCAP CLM

actions TC_ENA or TC_LABEL). Row and entry number is derived the following way:

Row = MAP_IDX, Entry = TC.

Number of entries per mapping: 8 entries.

QoS mappings can be shared between multiple VCAP CLM entries by defining the same mapping and

using the same entries in the mapping table. It is up to the user of the QoS mapping table to make sure

that entries are allocated so that they do not overlap unintentionally.

Each entry in the QoS mapping table (ANA_CL:MAP_TBL:MAP_ENTRY) contains a full set of new QoS

values (COSID, DEI, PCP, QoS class, DP level, DSCP, TC) to be used as new classified values instead

of the current classified values from basic classification and VCAP CLM. Each of the QoS values is gated

by an enable bit (ANA_CL:MAP_TBL:SET_CTRL) so that a mapping can for example define a complete

new set of QoS values by enabling all values or it can override selected values only. Note that

ANA_CL:MAP_TBL:SET_CTRL must be configured for each used row in the mapping table.

The following illustration shows an example of a frame for which a DSCP and a DEI/PCP mapping are

defined.

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