Cabletron Systems EMM-E6 Ethernet - Manual (Page 51)

CHAPTER 2: REQUIREMENTS / CONFIGURATIONS
2-4 EMM-E6 User’s Guide
2.1.2 Multimode Fiber Optic Network
When connecting a multimode fiber optic link segment to the hub (via
EPIM-F1/F2), ensure the network meets the following requirements:
• Cable Type - Use the EPIM-F1 and EPIM-F2 for the following
multimode fiber optic media:
- 50/125
µ
m fiber optic cabling
- 62.5/125
µ
m fiber optic cabling
- 100/140
µ
m fiber optic cabling
• Attenuation - You must 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 in a cable falls within the following
acceptable levels:
- 13.0 dB or less for a 50/125
µ
m fiber cable segment
- 16.0 dB or less for a 62.5/125
µ
m fiber cable segment
- 19.0 dB or less for a 100/140
µ
m fiber cable segment
• Budget and Propagation Delay - When you determine the
maximum fiber optic cable length to incorporate fiber runs into your
network, you must calculate and consider the fiber optic budget (a
total loss of 10.0 dB or less is permissible between stations) and total
network propagation delay.
To determine the fiber optic budget, combine the optical loss due to
the fiber optic cable, in-line splices, and fiber optic connectors.
Typical loss for a splice and connector (together) equals 1 dB or less.
Total propagation delay allowed for the entire network must not
exceed 25.6
µ
s in one direction (51.2
µ
s round trip). If the total
propagation delay between any two nodes on the network exceeds
25.6
µ
s, you must either reduce the delay or use a bridge.
• Length - The maximum possible multimode fiber optic cable length
is 2 km (2187.2 yards). However, IEEE 802.3 FOIRL specifications
specify a maximum of 1 km (1093.6 yards).
CH1Book Page 4 Wednesday, March 20, 1996 7:48 AM