Cabletron Systems 8H02-16 manual 3 100BASE-FX Fiber Optic Network

Network Requirements

Propagation Delay

Propagation delay is the amount of time it takes data to travel from the sending device to the receiving device.

Total propagation delay allowed for a 100BASE-TX (100 Mbps) network is 256 bit times or 2.56 microseconds (2.56 ∝s). If the total propagation delay between any two nodes on a 100BASE-TX network exceeds

2.56 ∝s, then use bridges or other devices to further segment the network.

Total propagation delay allowed for a 10BASE-T (10 Mbps) network is 256 bit times or 25.6 ∝s. If the total propagation delay between any two nodes on a 10BASE-T network exceeds 25.6 ∝s, then use bridges or other devices to further segment the network.

Temperature

The attenuation of PVC insulated cable varies significantly with temperature. At temperatures greater than 40°C (104°F), use plenum rated cables to ensure that cable attenuation remains within specification.

2.1.3100BASE-FX Fiber Optic Network

Ports 15 and 16 of the 8H02-16 support the Cabletron Systems FE-100FX fiber optic interface module. The FE-100FX meets the IEEE 802.3u standard. When connecting a fiber optic segment to the 8H02-16, the network must meet the following requirements:

Cable Loss

Test the fiber optic cable with a fiber optic attenuation test set adjusted for an 850 nm wavelength. This test verifies that the signal loss is within an acceptable level. The maximum loss for a multimode cable is 11.0 dB.

Fiber Optic Budget and Propagation Delay

Determine the maximum fiber optic cable length by calculating the fiber optic budget delay and total network propagation before fiber optic cable 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.

8H02-16 User’s Guide 2-3