KS8995MAL Micrel Inc, KS8995MAL Datasheet - Page 55

• Manufacturer Part Number: KS8995MAL
• Description: IC SWITCH 10/100 5PORT 128PQFP
• Manufacturer: Micrel Inc

Specifications of KS8995MAL

• Applications: *
• Mounting Type: Surface Mount
• Package / Case: 128-MQFP, 128-PQFP
• For Use With: 576-1017 - BOARD EVAL EXPERIMENT KS8995M
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

VLAN Address
The VLAN table is used for VLAN table look-up. If 802.1q VLAN mode is enabled (Register 5 bit 7 =1), this table is used to
retrieve VLAN information that is associated with the ingress packet. The information includes FID (filter ID), VID (VLAN ID),
and VLAN membership described below:
If 802.1q VLAN mode is enabled, KS8995MA assigns a VID to every ingress packet. If the packet is untagged or tagged with
a null VID, the packet is assigned with the default port VID of the ingress port. If the packet is tagged with non-null VID, the
VID in the tag is used. The look-up process starts from the VLAN table look-up. If the VID is not valid, the packet is dropped
and no address learning occurs. If the VID is valid, the FID is retrieved. The FID+DA and FID+SA lookups are performed. The
FID+DA look-up determines the forwarding ports. If FID+DA fails, the packet is broadcast to all the members (excluding the
ingress port) of the VLAN. If FID+SA fails, the FID+SA is learned.
Examples:
(1) VLAN Table Read (read the 3rd entry)
(2) VLAN Table Write (write the 7th entry)
May 2005
KS8995MA
Address
Format of Static VLAN Table (16 entries)
21
20-16
15-12
11-0
Write to Register 110 with 0x14 (read VLAN table selected)
Write to Register 111 with 0x2 (trigger the read operation)
Then
Read Register 118 (VLAN table bits 21-16)
Read Register 119 (VLAN table bits 15-8)
Read Register 120 (VLAN table bits 7-0)
Write to Register 118 (VLAN table bits 21-16)
Write to Register 119 (VLAN table bits 15-8)
Write to Register 120 (VLAN table bits 7-0)
Write to Register 110 with 0x04 (write static table selected)
Write to Register 111 with 0x6 (trigger the write operation)
Name
Valid
Membership
FID
VID
Description
1, the entry is valid.
0, entry is invalid.
Specify which ports are members of the VLAN.
If a DA look-up fails (no match in both static and
dynamic tables), the packet associated with this VLAN
will be forwarded to ports specified in this field.
E.g., 11001 means port 5, 4, and 1 are in this VLAN.
Filter ID. KS8995MA supports 16 active VLANs
represented by these four bit fields. FID is the mapped
ID. If 802.1q VLAN is enabled, the look-up will be based
on FID+DA and FID+SA.
IEEE 802.1q 12 bit VLAN ID.
Table 13. VLAN Table
55
Mode
R/W
R/W
R/W
R/W
Default
1
11111
0
1
M9999-051305
Micrel, Inc.