3Com TECHD-0000000050 manual Zpha Cross-over Configuration

When you have a straight cable coming in, you can use two straight cables. If both connected devices are end devices, you should use two cross-over cables. This is because when the ZPHA closes there must be a crossover between the two connected devices. Without having the two crossover cables on one side both cables between the two connected devices upon failure would be straight through and the connection would not complete. See Figure 2 - 11, “ZPHA Cross-over Configuration 2:

Figure 2 - 11: ZPHA Cross-over Configuration 2

If you have two end devices connected with two cross-over connections, you should configure the cables as follows:

•One side must have a crossover cable between the IPS and ZPHA devices with a straight through cable between the ZPHA and the connected device

•The other side should have a reversed setting with the cross-over cable connecting the ZPHA and the other device

UnityOne Modular Fiber/Copper ZPHA Installation Guide V 2.1

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