adm6995 ETC-unknow, adm6995 Datasheet - Page 29

• Manufacturer Part Number: adm6995
• Description: Port 10/100 Mb/s Single Chip Ethiernet Switch Controller
• Manufacturer: ETC-unknow

ADM6995L
ADMtek Inc.
3.19 Priority Setting
function, two EEPROM registers are needed to be programmed first :
* Port VID number at EEPROM register 0x01h~0x09h bit 13~10, register 0x28h~0x2bh
and register 0x2ch bit 7~0: ADM6995L will check coming packet. If coming packet is
non VLAN packet then ADM6995L will use PVID as VLAN group reference.
ADM6995L will use packet’s VLAN value when receive tagged packet.
* VLAN Group Mapping Register. EEPROM register 013h~022h define VLAN grouping
value. User use these register to define VLAN group.
User can define each port as Tag port or Untag port by Configuration register Bit 4. The
operation of packet between Tag port and Untag port can explain by follow example:
Example1: Port receives Untag packet and send to Untag port.
VLAN group resister. If destination port same VLAN as receiving port then this packet
will forward to destination port without any change. If destination port not same VLAN
as receiving port then this packet will be dropped.
Example2: Port receives Untag packet and send to Tag port.
VLAN group resister. If destination port same VLAN as receiving port than this packet
will forward to destination port with four byte VLAN Tag and new CRC. If destination
port not same VLAN as receiving port then this packet will be dropped.
Example3: Port receives Tag packet and send to Untag port.
If destination port same VLAN as receiving port than this packet will forward to
destination port after remove four bytes with new CRC error. If destination port not same
VLAN as receiving port then this packet will be dropped.
Example4: Port receives Tag packet and send to Tag port.
group resister. If destination port same VLAN as receiving port than this packet will
forward to destination port without any change. If destination port not same VLAN as
receiving port then this packet will be dropped.
It is a trend that data, voice and video will be put on networking, Switch not only deal
data packet but also provide service of multimedia data. ADM6995L provides two
priority queues on each port with N:1 rate. See EEPROM Reg.0x10h.
This priority function can set three ways as below:
* By Port Base: Set specific port at specific queue. ADM6995L only check the port
priority and not check packet’s content VLAN and TOS.
ADM6995L will check the port user define four bits of VLAN ID first then check
ADM6995L will check the port user define fours bits of VLAN ID first then check
ADM6995L will check the packet VLAN ID first then check VLAN group resister.
ADM6995L will check the user define packet VLAN ID first then check VLAN
Function Description
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