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Using the Passport 8100 Modules
Port Connection Problems
Port connection problems can usually be traced to a poor cable connection or to an
improper connection of the port cables at either end of the link. These types of
problems can be remedied by making sure that the cable connections are secure
and that the cables are connected to the correct ports at both ends of the link.
For more information about cabling, see "Cabling," next in this chapter.
Port connection problems can also be traced to the autonegotiation mode (refer to
"Autonegotiation
Cabling
Cabling for 10BASE-T networks can consist of 2-pair Category 3, 4, or 5
unshielded twisted pair (UTP) wiring. However, to cover future upgrades to Fast
Ethernet, Nortel Networks strongly recommends that you use all Category 5 cable
in your network.
Ethernet 10BASE-T network installations use cables consisting of two pairs of
twisted pair wires—one pair to send data and one to receive data. These wires
must connect to another 10BASE-T station that has the sending pair attached to its
receiving pair and vice versa. In this way, the two nodes can exchange data. If the
two nodes are wired alike, they both attempt to send data out on the same
RJ-45 pins. In such a case, a straight-through cable would not work. However, a
crossover cable would operate normally.
The Passport 8100 Series modules are designed to have Ethernet NICs connect
directly to their RJ-45 ports using straight-through (MDI) cables. However, if a
Passport 8100 module must connect to a hub or another switch that follows usual
conventions, a crossover cable (MDI-X) is required.
The 100 Mb/s ports are designed to operate using Category 5 UTP cabling only.
Category 5 UTP cable is a 2-pair cable certified to handle up to 100 Mb/s
bandwidth. To minimize crosstalk noise, maintain the twist ratio of the cable up to
the point of termination; untwist at any termination should not exceed 0.5 inch
(1.27 cm).
For best performance with respect to noise immunity and emissions, the unused
pairs in the 2-pair cable should be terminated at their characteristic impedance
(that is, 100 ohms) in the equipment at each end of the cable. All Nortel Networks
100BASE-TX equipment includes such a Common Mode Termination (CMT).
4-4
Modes" on
page
4-5) or the port interface.
204515-C
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