User manual

Wide Bank 28 DS3 - Release 2.4 July 2004 10-5
Maintenance
Replacing Low-Speed Cards
Replacing Low-Speed Cards
WARNING! SEE PROPER ELECTROSTATIC DISCHARGE (ESD)
PROCEDURES WHEN REMOVING AND HANDLING THE LOW-SPEED AND
C
ONTROLLER CARDS. WE RECOMMEND THAT YOU WEAR A RESISTANCE-STYLE
WRIST STRAP TO GROUND YOURSELF THROUGH THE EQUIPMENT CHASSIS. SEE
S
TATIC-SENSITIVE EQUIPMENT HANDLING PROCEDURES ON page 5-3 FOR
INSTRUCTIONS ON HOW TO USE A WRIST STRAP.
Low-speed cards come in two styles: the standard card and the Maintenance Service Option (MSO)
card. The procedures for swapping these cards are different, as described below. The Maintenance
Service Option includes not only a different style of card but also a specific minimum level of firmware
(1.47 or higher).
Maintenance Practices for Low-Speed Cards
There are two maintenance practices that you should follow when replacing low-speed cards to
minimize the effects on traffic. One practice is used for standard low-speed cards and the other is
used for MSO low-speed cards.
Standard Low-Speed Card Maintenance Practice
1. Plan to replace a failed low-speed card during a low-traffic period or when the circuits on the
card will not be carrying traffic. Removing a low-speed card disrupts service on all four circuits
on the card because there are no relays to maintain service through the spare card. So, replacing
cards during off-peak traffic times will minimize service disruptions.
2. Replace a failed low-speed card at the first opportunity. This will reduce the risk that other
failed circuits will be dropped because there are no spare circuits available.
3. Do not remove more than one low-speed card at the same time. Each card that is removed will
disrupt traffic on four circuits.
MSO Low-Speed Maintenance Practice
1. Replace a failed low-speed MSO Electronics card at the first opportunity. This will reduce the
risk that other failed circuits will be dropped because there are no spare circuits available.
2. Do not remove or replace more than one MSO Electronics card at a time. If one low-speed card
is removed, all four circuits on that card will move to the spare card. But when a second low-
speed card is removed, the resulting resource conflict will cause all circuits on all removed
cards to be dropped.