HP FlexFabric 11900 Switch Series Installation Guide

Pin assignments

Select an Ethernet twisted pair cable according to the RJ-45 Ethernet interface type on your device. An

RJ-45 Ethernet interface can be MDI (for routers and PCs) or MDIX (for switches). For the pinouts of RJ-45

Ethernet interfaces, see Table 48 and Table 49.

Table 48 RJ-45

MDI interface pinouts

10Base-T/100Base-TX

1000Base-T

nal Function

nal

Function

1 Tx+ Send data BIDA+ Bi-directional data cable A+

2 Tx- Send data BIDA- Bi-directional data cable A-

3 Rx+ Receive data BIDB+ Bi-directional data cable B+

4 Reserved N/A BIDC+ Bi-directional data cable C+

5 Reserved N/A BIDC- Bi-directional data cable C-

6 Rx- Receive data BIDB- Bi-directional data cable B-

7 Reserved N/A BIDD+ Bi-directional data cable D+

8 Reserved N/A BIDD- Bi-directional data cable D-

Table 49 RJ-45 MDI-X interface pinouts

10Base-T/100Base-TX

1000Base-T

nal Function

nal

Function

1 Rx+ Receive data BIDB+ Bi-directional data cable B+

2 Rx- Receive data BIDB- Bi-directional data cable B-

3 Tx+ Send data BIDA+ Bi-directional data cable A+

4 Reserved N/A BIDD+ Bi-directional data cable D+

5 Reserved N/A BIDD- Bi-directional data cable D-

6 Tx- Send data BIDA- Bi-directional data cable A-

7 Reserved N/A BIDC+ Bi-directional data cable C+

8 Reserved N/A BIDC- Bi-directional data cable C-

To ensure normal communication, the pins for sending data on one port should correspond to the pins for

receiving data on the peer port. When both of the ports on the two devices are MDI or MDIX, a crossover

Ethernet cable is needed. A cross-over cable connects devices of the same type. When one port is MDI

and the other is MDIX, a straight-through Ethernet cable is needed. A straight-through cable connects

devices of different types.

If an RJ-45 Ethernet interface with MDI/MDIX autosensing enabled can automatically negotiate pin roles.

The 11900 RJ-45 Ethernet interfaces support MDI/MDIX. By default, MDI/MDIX is enabled on a port.

Making an Ethernet twisted pair cable

To make an Ethernet twisted pair cable: