Operating Specifications - Cabletron Systems IRM-2 Installation Manual

NETWORK REQUIREMENTS/SPECIFICATIONS
• Attenuation - The fiber optic cable must be tested with a fiber optic
attenuation test set that is adjusted for an 850 nm wavelength. This test
verifies that the signal loss in a cable is within an acceptable level:
- 13.0 dB or less for 50/125 m fiber cable segment.
- 16.0 dB or less for 62.5/125 m fiber cable segment.
- 19.0 dB or less for 100/140 m fiber cable segment.
• Budget and Propagation Delay - When determining the maximum
fiber optic cable length, the fiber optic budget delay and total network
propagation should be calculated and taken into consideration before
fiber runs are incorporated in any network design. Fiber optic budget
is the combination of the optical loss due to the fiber optic cable,
in-line splices, and fiber optic connectors. Propagation delay is the
amount of time it takes a packet to travel from the sending device to
the receiving device.
• Length - The maximum allowable fiber optic cable length is 3 Km.
However, IEEE 802.3 specifications allow for a maximum of 1 Km.
2.2

OPERATING SPECIFICATIONS

The operating specifications for Cabletron Systems' IRM-2 are included
in this section. Cabletron Systems reserves the right to change these
specifications at any time without notice.
REPEATER FUNCTIONALITY
Delay Times (Port x In To Port x out)
Start of Packet:
Collision to JAM:
Preamble
Input:
Output:
2-2
1450 ns max.
1550 ns max.
Minimum of 40 bits to a maxi-
mum of 64 bits required.
64 bits min (last 2 bits are 1, 1).