Cabletron Systems BRIM E100 BRIM-E100 User Manual

Chapter 2: Cabling RequirementsPage 2-2BRIM-E100 User’s GuideJitterIntersymbol interference and reflections cause jitter in the bit cell timing,resulting in data errors. A 100BASE-TX link must not generate more than1.4 nanoseconds (ns) of jitter. If the cable meets the impedancerequirements for a 100BASE-TX link, jitter should not be a concern.CrosstalkCrosstalk is caused by signal coupling between the different cable pairscontained within a multi-pair cable bundle. 100BASE-TX transceivers aredesigned so that the user does not need to be concerned about cablecrosstalk, provided the cable meets all other requirements.NoiseNoise is caused by either crosstalk or externally induced impulses.Impulse noise may cause data errors if the impulses occur at very specifictimes during data transmission. Generally, the user need not be concernedabout noise. If noise-related data errors are suspected, it may be necessaryto either reroute the cable or eliminate the source of the impulse noise.UTP Propagation DelayPropagation delay is the amount of time it takes data to travel from thesending device to the receiving device. Total propagation delay allowedfor the network is 256 bit times. 256 bit times is equivalent to 2.56microseconds (μs) at 100 Mbps operation or to 25.6 μs at 10 Mbpsoperation. If the total propagation delay between any two nodes on thenetwork exceeds 256 bit times, then further segmentation of the networkthrough the use of bridges or other devices is required.TemperatureThe attenuation of PVC insulated cable varies significantly withtemperature. At temperatures greater than 40°C (104°F), CabletronSystems recommends the use of plenum-rated cables to ensure that cableattenuation remains within specification.