EMM-E6 Ethernet User's Guide

CHAPTER 2: REQUIREMENTS / CONFIGURATIONS
2-2 EMM-E6 User’s Guide
2.1.1 10BASE-T Twisted Pair Network
When connecting a 10BASE-T segment at any of the 10BASE-T hub
ports or a 10BASE-T Ethernet Port Interface Module (EPIM-T), ensure
that the network meets the following requirements:
• Length - The IEEE 802.3 10BASE-T standard requires that
10BASE-T devices transmit over a 100 meter (328 foot) link using
22-24 AWG unshielded twisted pair wire. However, cable quality
largely determines maximum link length. If you use high quality,
low attenuation cable, it may be possible achieve link lengths of up
to 200 meters. Cable delay limits maximum link length to 200
meters, regardless of the cable type.
• Insertion Loss - Between frequencies of 5.0 and 10.0 MHz, the
maximum insertion loss must not exceed 11.5 dB. This includes the
attenuation of the cables, connectors, patch panels, and reflection
losses due to impedance mismatches in the link segment.
• Impedance - Cabletron Systems 10BASE-T Twisted Pair products
work on twisted pair cable with 75Ω to 165Ω impedance.
Unshielded twisted pair cables typically have an impedance of
between 85Ω and 110Ω. You can also use shielded twisted pair
cables, such as IBM Type 1 cable, but keep in mind that this cable
has an impedance of 150Ω.
The high impedance of the IBM Type 1 cable increases signal
reflection. However, due to cable shielding, and its subsequent lack
of crosstalk between shielded pairs, this signal reflection has little
effect on the quality of the received signal.
Losses introduced by connections at punch-down blocks and other
equipment reduce total segment length. For each connector or
patch panel in the link, subtract 12 meters from the total length of
your cable.
NOTE
CH1Book Page 2 Wednesday, March 20, 1996 7:48 AM