Cabletron Systems SEH100TX-22 User Manual

 

Installation Requirements and Specifications

 

The device at the other end of the twisted pair segment must meet IEEE 
802.3u 100BASE-T specifications. When connecting a 100BASE-TX 
twisted pair segment to the SEH twisted pair network ports and the 
EPIM-100TX module, the network must meet the following 
requirements:

 

The IEEE 802.3u 100BASE-T standard requires that 100BASE-TX 
devices have the ability to transmit over a 100 meter (328 foot) link using 
Category 5 UTP wire. The cable used must meet the Horizontal 
requirements and 90-meter length limitations. Patch cable should be used 
on each end of the Horizontal wire to make connections to punch down 
blocks, panels, or other connecting devices. The combined lengths of the 
patch cords must not exceed 10 meters so the total segment length 
including the patch cords does not exceed 100 meters (328 feet).

Category 5 cables are marked on the cable jacket as Cat 5, Category 5, 
Level 5, Level V, or an equivalent.

UTP cables typically have an impedance of between 85 and 110 ohms.

Intersymbol interference and reflections cause jitter in the bit cell timing, 
resulting in data errors. A 100BASE-TX link must not generate more than 
1.4 ns of jitter. If the cable meets the impedance requirements for a 
100BASE-TX link, jitter should not be a concern. 

Crosstalk is caused by signal coupling between the different cable pairs 
contained within a multi-pair cable bundle. 100BASE-TX transceivers are 
designed so that the user does not need to be concerned about cable 
crosstalk, provided the cable meets all other requirements.

Noise is caused by either crosstalk or externally induced impulses. 
Impulse noise may cause data errors if the impulses occur at very specific 
times during data transmission. Generally, the user need not be concerned 
about noise. If noise-related data errors are suspected, it may be necessary 
to either reroute the cable or eliminate the source of the impulse noise.