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
10-/100-Mbit/s port configuration (continued)
Each terminal is considered to be bidirectional, when pulled low by either TNETX3270 or by the PHY (or other external connections). If neither pulls the terminal low, then the pullup resistor maintains a value of 1 on the terminal. When the PHY does not pull down a terminal, then it can determine the desired option that is being requested by TNETX3270. TNETX3270 observes the terminal to determine if its desired option has been granted.
The sense of these three signals is such that the
The status of the link for each of these ports is indicated on the MxxLINK terminal and observable in the port's Portxstatus register. The MxxLINK terminal plays no part in the negotiation of speed or duplex or their recording in the Portxstatus register.
The behavior of these terminals is summarized in Tables 13 and 14.
Table 13. Speed Configuration ± MxxFORCE10
Portxcontrol |
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| Portxstatus | OUTCOME |
| MxxFORCE10 |
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req10 |
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| SPEED | (Mbit/s) | |||
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0 | → |
| Floating 1 | → | 1 | 100 | |
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1 | → | Driven 0 (by TNETX3270) | → | 0 | 10 | ||
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X |
| Driven 0 (by PHY) | → | 0 | 10 | ||
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Table 14. Duplex Configuration ± MxxFORCEHD
Portxcontrol |
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| Portxstatus | OUTCOME |
| MxxFORCEHD |
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reqhd |
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| DUPLEX | ||||
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0 | → |
| Floating 1 | → | 1 | Full duplex | |
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1 | → | Driven 0 (by TNETX3270) | → | 0 | Half duplex | ||
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X |
| Driven 0 (by PHY) | → | 0 | Half duplex | ||
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10-/100-Mbit/s port configuration in a nonmanaged switch
The
1.The EEPROM loads the req10 and reqhd bits of the Portxcontrol registers as required. If either of these bits becomes a 1, the corresponding terminal is not pulled low and thus, floats high. (The reqnp bit also can be loaded from EEPROM to enable/disable
2.The PHYs either:
a.Look at the MxxFORCE10 and MxxFORCEHD terminals and configure themselves as specified (if not autonegotiating), or as the highest common denominator with the link partner, if they are autonegotiating. If the PHYs use the information on these terminals, they must wait until TNETX3270 loads the EEPROM contents before doing so (this may require delaying the reset to the PHYs if necessary).
b.Ignore TNETX3270 requests and configure themselves in some other manner.
3.The PHYs (or external system) then drive MxxFORCE10 and MxxFORCEHD low for those features that are supported only at the lower performance. These are continuously sampled into the Portxstatus register.
4.The MACs then operate as indicated by the Portxstatus register.
POST OFFICE BOX 655303 •DALLAS, TEXAS 75265 | 35 |
