GE PACSystems RX7i, User Manual

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Chapter 3. Installation and Start-up: Rack-based and RX7i Embedded Interface
GFK-2224Q January 2017 27
Each switch port auto-negotiates (by default) to the correct link speed and duplex mode for the device
connected to the other end of the link. Each port operates independently, so devices at two different speeds
and/or duplex modes may be attached to the two ports. Each port also automatically detects the attached
cable and will work properly with either straight-through or crossover cables (by default).
Caution
The two Ethernet ports on the Ethernet Interface must not be connected,
directly or indirectly, to the same device. The connections in an Ethernet
network based on twisted pair cabling must form a tree and not a ring,
otherwise duplication of packets and network overload may occur.
Caution
The IEEE 802.3 standard strongly discourages the manual configuration of
duplex mode for a port (as would be possible using Advanced User Parameters).
Before manually configuring duplex mode for an Ethernet Interface port using
advanced user parameters (AUP), be sure that you know the characteristics of
the link partner and are aware of the consequences of your selection. Setting
both the speed and duplex AUPs on an IC698 Ethernet Interface port will disable
the port’s auto-negotiation function. If its link partner is not similarly manually
configured, this can result in the link partner concluding an incorrect duplex
mode. In the words of the IEEE standard: “Connecting incompatible DTE/MAU
combinations such as full duplex mode DTE to a half-duplex mode MAU, or a full-
duplex station (DTE or MAU) to a repeater or other half-duplex network, can lead
to severe network performance degradation, increased collisions, late collisions,
CRC errors, and undetected data corruption.”
Note: If both speed and duplex mode of an Ethernet interface port are forced using the Advanced User
Parameters file, that port will no longer perform automatic cable detection. This means that if you
have the Ethernet interface port connected to an external switch or hub port you must use a crossover
cable. If you have the Ethernet interface port connected to the uplink port on an external switch or
hub, or if you have the Ethernet interface port directly connected to another Ethernet device, you must
use a normal cable.
Connection to a 10Base-T / 100Base Tx Network
Either shielded or unshielded twisted pair cable may be attached to a port. The 10Base-T/100Base Tx twisted
pair cables must meet the applicable IEEE 802 standards. Category 5 cable is required for 100BaseTX
operation.
Each Ethernet port automatically senses whether it is connected to a 10BaseT or 100BaseTX network, half-
duplex or full-duplex. (The automatic negotiation of speed and/or duplex mode can be explicitly overridden
using Advanced User Parameter settings).