
12 LightStream 1010 ATM Switch 622 SM/MM Port Adapter Module Configuration Note
Installing and Replacing PAMs
Each CAM contains a bus-type connector that mates with the system backplane. Each card
connectorconsistsofaset of tiered pins, in three lengths. The pins sendspecificsignalstothe system
as they make contact with the backplane. The system assesses the signals it receives and the order
in which it receives them to determine what event is occurring and what task it needs to perform,
such as reinitializing new interfaces or shutting down removed ones.
For example, when inserting a CAM, the longest pins make contact with the backplane first, and the
shortest pins make contact last. The system recognizes the signals and the sequence in which it
receives them. The system expects to receive signals from the individual pins in this logical
sequence, and the ejector levers help to ensure that the pins mate in this sequence.
When you remove or insert a PAM, the backplane pins send signals to notify the system, which then
performs as follows:
1Rapidly scans the backplane for configuration changes.
2Initializes all newly inserted PAMs, noting any removed interfaces and placing them in the
administratively shutdown state.
3Brings all previously configured interfaces on the PAM back to the state they were in when they
were removed. If a PAM, similar to the one that was removed, has been reinserted into a slot,
then its ports are configured and brought online up to the port count of the original PAM.
Unconfigured PAMs installed for the first time start up in the shutdown state. The system
identifies them as present but unconfigured. Each must be manually configured from the
command line.1
Hot-swap functionality enables you to add, remove, or replace PAMs with the system online, which
provides a seamless method to users on the network, maintains all routing information, and ensures
session preservation.
When you insert a new PAM, the system runs a diagnostic test on the new interfaces and compares
them to the existing configuration. If this initial diagnostic fails, the system remains offline for
another 15 seconds while it performs a second set of diagnostic tests to determine whether or not the
PAM is faulty and if normal system operation is possible.
If the second diagnostic test passes, which indicates that the system is operating normally and the
new PAM is faulty, the system resumes normal operation but leaves the new interfaces disabled.
If the second diagnostic test fails, the system crashes, which usually indicates that the new PAM has
created a problem in the bus and should be removed.
Caution To avoid erroneous failure messages, allow at least 15 seconds for the system to
reinitialize and note the current configuration of all interfaces before you remove or insert another
PAM.
Tools Required You need a 3/16-inch flat-blade screwdriver to remove any filler (blank) PAMs and to tighten the
captive installation screws that secure the CAMs and PAMs in their slots. Whenever you handle
CAMs and PAMs, you should use a wrist strap or other grounding device to prevent electrostatic
discharge (ESD) damage. See the section “Preventing Electrostatic Discharge Damage” in the
chapter “Preparing for Installation” in the LightStream 1010 ATM Switch User Guide.
1. Instructions for initial interface configurations are in the publication LightStream 1010 ATM Switch Software
Configuration Guide.