Appendix C: Network Planning and Configuration
Page C-2
MicroMMAC Installation Guide
C.1.2 10BASE-T UTP and STP Cable
The devices and 10BASE-T twisted pair segments connected to the
MicroMMAC and EPIM-T must meet the IEEE 802.3 specifications
listed below:
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. With high quality, low attenuation cable, link lengths of up to
200 meters are achievable. Cable delay limits maximum link length to
200 meters, regardless of the cable type. Cabletron Systems does not
recommend UTP cable lengths of more than 100 meters.
Insertion Loss
The maximum insertion loss allowed for a 10BASE-T link is 11.5 dB
between frequencies of 5.0 and 10 MHz. 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 products work on twisted pair cable with
75 to 165 ohms impedance. Unshielded twisted pair cables typically have
an impedance of between 85 to 110 ohms.
Shielded twisted pair cables, such as IBM Type 1 cable, are also used. The
impedance of IBM Type 1 cable is typically 150 ohms. Higher impedance
increases signal reflection, but because the cable is shielded, signal
reflection has little effect on the quality of the received signal due to the
lack of crosstalk between the shielded cable pairs.
NOTE
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.
