VSC7511 datasheet(65/324 Pages) MICROSEMI

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Functional Descriptions

VMDS-10488 VSC7511 Datasheet Revision 4.2

The following table lists the registers associated with general data extraction.

It is programmable which VLAN tags are recognized. The use of Layer-3 and Layer-4 information for

classification and forwarding can also be controlled.

The device recognizes three different VLAN tags:

•

Customer tags (C-TAGs), which use TPID 0x8100.

•

Service tags (S-TAGs), which use TPID 0x88A8 (IEEE 802.1ad).

•

Service tags (S-TAGs), which use a custom TPID programmed in SYS::VLAN_ETYPE_CFG.

The device can parse and use information from up to two VLAN tags of any of the kinds described above.

By default, the outer VLAN tag is extracted and used for both the basic classification and the VCAP IS1

key generation. However, for both the basic classification and the VCAP IS1, there is an option to use the

inner VLAN tag instead for frames with at least two VLAN tags. For basic classification, this is controlled

in VLAN_CFG.VLAN_INNER_TAG_ENA and affects both QoS, DP, and VLAN classification as well as

the frame acceptance filter. For IS1, this is controlled per lookup in S1_VLAN_INNER_TAG_ENA. Note

that several keys in IS1 always contain both the inner VLAN tag and the outer VLAN tag.

Various blocks in the device uses Layer-3 and Layer-4 information for classification and forwarding.

Layer-3 and Layer-4 information can be extracted from a frame with up to two VLAN tags. Frames with

more than two VLAN tags are considered non-IP frames.

The actual use of Layer-3 and Layer-4 information for classification, forwarding, and rewriting is enabled

in SYS::PORT_MODE.L3_PARSE_CFG. The following blocks are affected by this functionality:

•

Basic classification: QoS, DP, and DSCP classification, link aggregation code generation, CPU

forwarding

•

VCAP: TCAM keys (IS1, IS2) using Layer 3 and Layer4 information

•

Analyzer: Flooding and forwarding of IP multicast frames

•

Rewriter: Rewriting of IP information

3.7.2

Frame Acceptance Filtering

The following table lists the registers associated with frame acceptance filtering.

Based on the configurations in the DROP_CFG and PORT_MISC registers, the classifier instructs the

queue system to drop or forward certain frames types, such as:

•

Frames with a multicast source MAC address

Table 26 •

General Data Extraction Registers

Description

Replication

SYS::PORT_MODE.L3_PARSE_CFG

Enables the use of Layer 3 and 4 protocol

information for classification and frame

processing.

Per port

SYS::VLAN_ETYPE_CFG

Ethernet Type for S-tags in addition to default

value 0x88A8.

None

ANA:PORT.VLAN_CFG.VLAN_INNER_TAG_ENA Enables using inner VLAN tag for basic

classification if available in incoming frame.

Per port

ANA:PORT:S1_VLAN_INNER_TAG_ENA

Enables using inner VLAN tag for IS1 key

generation if available in incoming frame.

Per port per

IS1 lookup

Table 27 •

Frame Acceptance Filtering Registers

Description

Replication

DEV::PORT_MISC

Configures forwarding of special frames.

Per port

ANA:PORT:DROP_CFG

Configures discarding of illegal frame types.

Per port

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