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TNETX3270

ThunderSWITCH 24/3 ETHERNET SWITCH

WITH 24 10-MBIT/S PORTS AND 3 10-/100-MBIT/S PORTS

SPWS043B – NOVEMBER 1997 – REVISED APRIL 1999

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

frame routing

VLAN support

The internal routing engine supports the IEEE Std 802.1Q VLANs as shown in Figure 8 and described in the

following paragraphs.

Source

and

Destination

Lookups

IEEE Std

802.1Q

Format

Frame

Header

Non-

IEEE Std

802.1Q

Format

Frame

Receive

Header

Inserted

rxacc

= 1

Header Inserted

Queue

Manager

RAM

Queue

Manager

Header

IEEE Std

802.1Q

Format

Frame

Header

Non-

IEEE Std

802.1Q

Format

Frame

Transmit

Source Port’s

PortxQtag

Inserted

VLAN ID

Reset 0x0001

Header

Stripped

Header

Retained

VLANnQID

VLAN ID

Lookup

Source Address (SA)

Destination Address (DA)

Reset

1st Location:

0x001

All Others:

0x000

No Match

VLAN and

Ethernet

Addresses

VLAN ADDR

Reset to

All 0s

VLAN

Index

Frame-Routing

Algorithm

UnkUniPorts

UnkMultiPorts

UnkSrcPorts

UnkVLANPort

TxBlockPorts

RxUniBlockPorts

RxMultiBlockPorts

MirrorPort

UplinkPort

TrunkMapx

TrunkxPorts

NLearnPorts

Source Port Number

Port Routing Code

Port Numbers,

Time Stamps

Locked, Secure,

NBLCK, New

Port Information

Reset is

Don’t Care

Record

Number

Match

Port

Information

All Ports

Portxcontrol

VLAN

Ports

Nauto

UnkVLAN

Lshare

Disable

VLANnPorts

Reset to

All 1s

IALE

If (equal or

txacc

= 1)

Then Strip Header,

Otherwise,

Keep Header

If VLAN ID = 0x000

VLAN ID Replaced

Header

Possibly

Inserted

Nage

Mirror

SysControl

Unicast/

Multicast

Compare

VLAN IDs

Figure 8. VLAN Overview