Texas Instruments TNETX3270 Spanning-tree support, Aging algorithms, Frame-routing determination

Page 41

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

spanning-tree support

Each port provides independent controls to block reception or transmission of frames, for learning of addresses, or to disable the port on a per-port basis. Blocking can be overridden to allow reception or transmission of spanning-tree frames.

aging algorithms

time-threshold aging

When processing (learning) addresses, the IALE adds the source address to the table and tags it with a time stamp. If another frame is received with this source address, then the time stamp is refreshed. If the aging counter expires before another frame is received from this source address, then the address is deleted from the table. If the table is full, then the oldest address is deleted to make room for a new address, even if the age for this address has not expired.

table-full aging

In table-full aging, the oldest address (or one of the oldest addresses if there is more than one) is automatically deleted from the IALE records only if the table is full and a new address needs to be added to the table. In this mode, the age stamp for the addresses is not refreshed.

frame-routing determination

When a frame is received, its 48-bit destination and source addresses are extracted and the VLAN index is determined. The destination address and VLAN index are then looked up in the IALE records to determine if a match exists. If a match is found, the information associated with the record is passed on to the frame-routing algorithm. After removing disabled ports and checking for mirrored and trunking ports, the frame is sent to the correct ports and the source address time stamp is reported.

The source address and VLAN index combination also are looked up in the IALE records to determine if a match exists. If a match is found, additional information is provided to the routing process. Figure 9 provides a flow diagram of the routing algorithm.

POST OFFICE BOX 655303 •DALLAS, TEXAS 75265

41

Image 41

Contents With 24 10-MBIT/S Ports and 3 10-/100-MBIT/S Ports TNETX3270 ThunderSWITCH 24/3 ETHERNET SwitchDescription With 24 10-MBIT/S Ports and 3 10-/100-MBIT/S PortsContents ThunderSWITCH 24/3 ETHERNETPGV Package TOP View  24/3 ThunderSWITCHTerminal Internal Description Name RESISTOR³ Terminal Internal Description Name Resistor 10-/100-Mbit/s MAC interface ports 24±26³10-/100-Mbit/s MAC interface ports 24±26 ² Terminal FunctionsDras Dcas Sdram interfaceDclk DrasHost DIO interface Jtag interface Serial MII management PHY interfaceEeprom interface Miscellaneous Power interfaceSummary of signal terminals by signal group function Vlan DIO register groupsInternal Register and Statistics Memory Map SIO Detailed DIO Register MapByte DIO Address VLAN3QID VLAN2QID VLAN1QID VLAN0QIDVLAN5QID VLAN4QID VLAN7QID VLAN6QIDVLAN19QID VLAN18QID VLAN17QID VLAN16QIDVLAN21QID VLAN20QID VLAN23QID VLAN22QIDTNETX3270 reset reinitializes the TNETX3270 0x40000x5FFF IntenableFindnode23±16 Findnode31±24 Findnode39±32 Findnode47±40 Findcontrol Findnode7±0 Findnode15±8Receiving/transmitting management frames State of DIO signals during hardware resetInterface description Network management port Frame format on the NM port FCS Vlan IDTpid TCI CRCMbit/s and 10-/100-Mbit/s MAC interface receive control MII serial management interface PHY managementGiant long frames Short framesData transmission Receive filtering of framesTransmit control Adaptive performance optimization APO transmit pacingUplink pretagging Receive versus transmit prioritySource Port Source-Port Pretag EncodingPort 27 NM Received Pretag Port AssignmentsTAG GND Eeprom interfaceEdio TNETX3270 Eclk SCL SDA Interaction of Eeprom load with the SIO register Outcome Stop Load Initd ² Fault LED EclkSummary of Eeprom load outcomes Summary of Eeprom Load OutcomesJtag Instruction Opcodes Jtag interfaceHighz instruction LED interfaceLED Status Bit Definitions and Shift Order Hardware configurationsLamp test Multi-LED displayTNETX3270 TNETE2008 Terminal Mbit/s Interface ConnectionsM03TXD M04TXD Port CLK Sync TXD3M06TXD M03COLConnecting to TNETE2008 PHY² Switch TNETE2101 Terminal 10-/100-Mbit/s port configuration10-/100-Mbit/s MAC interfaces ports 24±26 100-Mbit/s Interface Connections10-/100-Mbit/s port configuration in a nonmanaged switch Speed Configuration ± MxxFORCE10Duplex Configuration ± MxxFORCEHD 10-/100-Mbit/s port configuration in a managed switch Sdram Terminals Not Driven by the TNETX3270 Sdram interface TNETX3270 Terminal Interface to SDRAMsTerminals Sdram Terminal Function TNETX3270 Held Sdram Terminal Terminal FunctionSDRAM-type and quantity indication TNETX3270 State Terminal During ResetInitialization RefreshIale Frame routingVlan support Ieee Std 802.1Q headers ± transmission Address maintenanceIeee Std 802.1Q headers ± reception Frame-routing determination Spanning-tree supportAging algorithms Frame-Routing Algorithm SPWS043B ± November 1997 ± Revised April CDE Port mirroringFlow control Port trunking/load sharingIeee Std 802.3 flow control Collision-based flow controlPause frame reception Internal wrap test PHY TNETX3270 Duplex wrap testCopy to uplink Parameter Test Conditions MIN TYP MAX Unit Recommended operating conditionsMIN NOM MAX Unit Test measurement Parameter MIN MAX Unit MIN MAX Unit10-/100-Mbit/sreceive ports 24, 25 10-/100-Mbit/s MAC interfaceTiming requirements see Note 7 and Figure 10-/100-Mbit/stransmit ports 24, 25, Timing requirements see FigureSdram command to command see Figure Sdram subcycle TdDA Delay time, from Dclk ↑ to DA InvalidDclk Dras DcasSDATA7± Z SDATA0 DIO/DMA interfaceDIO/DMA write cycle DIO/DMA read cycle Serial MII Management Read/Write Cycle Parameter TNETX3150 TNETX3150A Unit MIN MAX Eeprom² During hard reset, Ledclk runs continuously TdLEDDATA Delay time, from LEDCLK↑ to 1st LED invalidTsuRESET Setup time Low before Oscin ↑ Power-up Oscin and Reset Timing requirements see FigureThRESET Hold time Low after Oscin ↑ TtOSCIN Transition time, Oscin rise and fallMechanical Data Important Notice