User manual

Product Description
Low-Speed (LS) Redundancy
2-24 July 2004 Wide Bank 28 DS3 - Release 2.4
Maintenance Service Option (MSO)
In addition to the circuit failure protection provided by Standard DS1 and E1 cards, MSO DS1 and
E1 cards will automatically switch low-speed service to the spare card when the electronics are
manually removed from a system. With MSO cards, the service interruption time is less than 50
milliseconds compared to 15 seconds when replacing standard cards.
The Maintenance Service Option (MSO) low-speed circuit card is made up of two separating
sections called the MSO Electronics card and the MSO Relay card. By separating these sections, a
customer can replace the one-to-four (or one-to-three for E1) failed DS1/E1 electronic circuits of
that MSO Electronics card while the MSO Relay card automatically maintains the four DS1 (three
E1) circuits by switching them to the spare low-speed circuit card. Once new MSO Electronics are
inserted and pass self-test, the four circuits (three E1) currently on the spare card are automatically
switched back to the “home” circuits.
Figure 2-10 MSO Electronics and MSO Relay Cards
When joined together, the MSO Electronics and MSO Relay cards fit the same form-factor of the
standard low-speed card. Therefore, the MSO DS1 or E1 card is compatible with all Wide Bank 28
DS3 systems. The MSO Electronics card contains all the necessary electronics for full operation of
all four circuits of the MSO Quad DS1 card or all three circuits of the MSO E1 card. This section
MSO card assembly,
comprising an MSO Electronics
section and an MSO Relay
With MSO Relay section
installed in chassis, the
MSO Electronics section
can be removed without
interrupting service
section, replaces standard
low-speed circuit card