3Com DUA3700-0BAA04 manual ATM Cabling, Dirt on the Fiber Optic Lens

ATM Cabling E-3

ATM Cabling	When planning the installation, thoroughly inspect the present cabling to
	determine if it meets the specifications in the cabling system or standards
	used at the site.
	In addition to adhering to the local standards, all cable must conform to
	the American National Standard ATM Physical Layer Medium Dependent
	(PMD) standard, ISO.166-1990, American National Standards Institute,
	which defines the Physical Medium Dependent (PMD) layer of the ATM
	network. Currently, there are two approved PMD standards: Multi-mode
	Fiber (MMF-PMD), which is defined in ANSI standard X.3-166-1992, and
	Single Mode Fiber (SMF-PMD), which is defined in ANSI standard
	x.3-184-198x.
	3Com supports multi-mode fiber (MMF-PMD) 62.5/125 µm and Category
	one (1) single mode fiber (short reach) (SMF-PMD). When deciding
	whether to use multi-mode or single mode fiber, determine the maximum
	interstation distance (the distance from the CoreBuilder 7000 to any
	potential end station):

If the maximum interstation distance is less than or equal to 2

￿kilometers (1.25 miles), use multi-mode fiber (MMF-PMD).

If the maximum interstation distance is greater than 2 kilometers (1.25 miles) and less than or equal to 14.4 kilometers (8.6 miles), use single mode fiber (short reach) (SMF-PMD).

Caring for Fiber Optic Fiber optic transceivers are sensitive optical devices that need careful Transceivers handling. The following information offers suggestions about caring for

fiber optic cable.

Dirt on the Fiber Optic Lens

If dirt collects on the fiber optic lens, you may notice that the LED for an ATM port either does not light or lights yellow. You may also notice degraded performance of that port, as indicated by a decrease in the Link Error Rate (LER) estimate for that port.

To prevent dust from collecting on the fiber optic lens, keep the dust covers on the ports at all times when they are not in use. To clean a fiber optic lens when it becomes dirty, see the section “Cleaning Dirty Fiber Optic Cables”.