KS8993 datasheet(13/35 Pages) MICREL

13 / 35 page

April 2009

KS8993

Micrel

Group

I/O Names

Active Status

Description

VMDIS

VLAN Mismatch Discard control.

Pulled low = Constrict multicast and broadcast packets to VLAN.

Pulled high = Constrict all packets to VLAN (default).

PRSV

Reserve priority buffers.

Pulled low = No buffers reserved (default).

Pulled high = Reserve 96 buffers per port for high priority queue.

PBASE[2:0]

Priority base value used to compare with priority tag in 802.1p tag. When a packet is

received that has a 802.1p tag and 802.1p processing is enabled (Px_1PEN=H), the

PBASE value is compared to the tag priority field. If the packet tag is greater than or

equal to the PBASE value, the packet is sent to the higher priority transmit queue

while tags less than PBASE are sent to the lower priority queue. (default = 100).

PV12

VLAN mask bits. Used to select which ports are seen from any particular port. Use

PV13

the table below to select VLAN operation.

PV21

P1_V defined as (PV13, PV12, 1)

PV23

P2_V defined as (PV23, 1 , PV21)

PV31

P3_V defined as (1 , PV32, PV31)

PV32

P[3:1]_V

Port

VLAN State

Ports 1 and 2 in VLAN

Ports 1 and 3 in VLAN

Ports 1, 2 and 3 in VLAN (default)

Ports 1 and 2 in VLAN

Ports 2 and 3 in VLAN

Ports 1, 2 and 3 in VLAN (default)

Ports 1 and 3 in VLAN

Ports 2 and 3 in VLAN

Ports 1, 2 and 3 in VLAN (default)

Note that a minimum of 2 ports are required for each VLAN. The VLAN configuration

is viewed from the receiver perspective. All states not listed above are invalid.

P[3:1]_1PEN

Enables 802.1p prioritizing on a per port basis. The enable is from the receive

perspective. If the 802.1p processing is disabled or there is no tag, priority is dete-

mined by the P[3:1]_PP bit.

Pulled low = Disable 802.1p prioritizing (default).

Pulled high = Enable 802.1p prioritizing.

P[3:1]_PP

Selects port receive priority in the absence of 802.1p handling.

Pulled low = Low priority (default).

Pulled high = High priority.

P[3:1]_TAGINS

Inserts 802.1p tag in received packets if not already existent. The priority field is set

based on the port P[3:1]_PP bit. For the P[3:1]_PP bit tied low, the priority field is set

to 000 and for the P[3:1]_PP bit tied high, the priority field is set to 111.

Pulled low = No change to received packet (default).

Pulled high = Insert 802.1p tag.

Note that if P[3:1]_TAGINS and P[3:1]_TAGRM are both set for the same port, there

is no change to the packet.

P[3:1]_TAGRM

Removes 802.1p tag in received packets if they exist.

Pulled low = No change to received packet (default).

Pulled high = Remove 802.1p tag.

Note that if P[3:1]_TAGINS and P[3:1]_TAGRM are both set for the same port, there

is no change to the packet.

P[3:1]_TXQ2

Selects transmit queue split on a per port basis. The split sets up high and low priority

queues.

Pulled low = Single transmit queue (default)

Pulled high = Separate high and low transmit queues

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