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Cisco ONS 15454 SDH Product Overview

Card Protection

Cisco ONS 15454 SDH Product Overview, R3.4

September 2002

Electrical Protection

In 1:1 protection, a working card is paired with a protect card of the same type. If

the working card fails, the traffic from the working card switches to the protect

card. When the failure on the working card is resolved, by default traffic

automatically reverts to the working card.

1:N protection operates only at the E-1 and DS-3 levels. The 1:N protect cards

must be the same speed as their working cards. For example, an E1-N-14 card

protects E1-N-14 cards, and a DS3i-N-12 card protects DS3i-N-12 cards. Each

side of the shelf assembly has only one card that protects all of the cards on that

side.

Optical Protection

The ONS 15454 SDH supports 1+1 protection to create redundancy for optical

cards and spans. With 1+1 protection, one optical port can protect another optical

port; therefore, in any two high-speed slots a single working card and a single

dedicated protect card of the same type (for example, two STM-16 cards) can be

paired for protection. If the working port fails, the protect port takes over. 1+1

span protection can be either revertive or non-revertive.

Because the STM-1 card is a multiport card, port-to-port protection is available.

The portson the protect card support the corresponding portson the working card.

Protection Switching

The ONS 15454 SDH supports revertive and non-revertive, unidirectional or

bidirectional switching for optical signals. 1:N electrical protection is always

revertive and bidirectional; 1:1 electrical protection is also bidirectional but

provides the revertive or non-revertive option.

When a failure occurs and automatic protection switching (APS) switches the

signal from the working cardto the protect card, revertiveswitching automatically

switches the signal back to the working card after the provisionable revertive time

period has elapsed. With non-revertive switching, traffic does not automatically

revert to the working card when the working card reverts to active status.

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Cisco ONS 15454 SDH Especificaciones Pagina 20