Cabletron Systems EMM-E6 Ethernet Manual De Usuario

CHAPTER 2:  REQUIREMENTS / CONFIGURATIONS

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