Specifications

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Cisco ONS 15454 Troubleshooting and Maintenance Guide

November 2001

Chapter 4 Card Reference

Electrical Card Protection

The physical DS-1 or DS-3 interfaces on the ONS 15454 backplane use the working card until the

working card fails. When the node detects this failure, the protection card takes over the physical DS-1

or DS-3 electrical interfaces through the relays and signal bridging on the backplane. Figure 4-2 shows

the ONS 15454 in a 1:N protection configuration. Each side of the shelf assembly has only one card

protecting all of the cards on that side.

Figure 4-2 ONS 15454 cards in a 1:N protection configuration

4.2.2.1 Revertive Switching

1:N protection supports revertive switching. Revertive switching sends the electrical interfaces (traffic)

back to the original working card after the card comes back online. Detecting an active working card

triggers the reversion process. There is a variable time period for the lag between detection and

reversion, called the revertive delay, which you can set using the ONS 15454 software, Cisco Transport

Controller (CTC). To set the revertive delay, see the Cisco ONS 15454 Installation and Operations

Guide. All cards in a protection group share the same reversion settings. 1:N protection groups default

to automatic reversion.

4.2.2.2 Protection Guidelines, 1:N

Several rules apply to 1:N protection groups in the ONS 15454:

• Working and protect card groups must reside in the same card bank (A or B)

• The 1:N protect card must reside in Slot 3 for side A and Slot 15 for side B

• Working cards may sit on either or both sides of the protect card

The ONS 15454 supports 1:N equipment protection for all add-drop multiplexer configurations (ring,

linear, and terminal), as specified by Telcordia GR-253-CORE.

The ONS 15454 automatically detects and identifies a 1:N protection card when the card is installed in

Slot 3 or Slot 15. However, the slot containing the 1:N card in a protection group must be manually

provisioned as a protect slot because by default all cards are working cards.

TCC+

XC10G

AIC (Optional)

XC10G

TCC+

Working

1:N Protection

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