Texas Instruments THUNDER TNETX3270 User Manual

Page 49

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

TNETX3270

Figure 10. Internal Wrap Example

duplex wrap test

Duplex wrap test is similar to internal wrap mode (see Figure 11). The ports can be set to accept frame data
that is wrapped at the PHY. This permits network connections between the device and the PHY to be verified.
Any port can be the source port (not just the NM port as shown in Figure 10). By using multicast/broadcast
frames, traffic can be routed selectively between ports involved in the test or return the frame directly before
retransmission on the uplink. Software control of the external PHYs is required to configure them for loopback.

If the internal PCS is in use (port configured in PMA mode) loopback in PCSxcontrol also must be asserted. This
causes MxxEWRAP to be high, forcing external PMD into loopback mode.

Duplex frame-wrap test mode is selected by setting dpwrap in Systest. When selected, the port is forced into
full duplex, allowing it to receive frames it transmits.

The switch is configured in the same manner as internal wrap.

TNETX3270

PHY

Figure 11. Duplex Wrap Example