7-4
Cisco ONS 15454 Reference Manual, R7.0
78-17191-01
Chapter 7 Card Protection
7.1 7.1.2 1:N Protection
7.1.2.1 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, refer to the “Turn Up a Node” chapter in the Cisco ONS
15454 Procedure Guide. All cards in a protection group share the same reversion settings. 1:N protection
groups default to automatic reversion.
Caution A user-initiated switch (external switching command) overrides the revertive delay, that is, clearing the
switch clears the timer.
7.1.2.2 1:N Protection Guidelines
There are two types of 1:N protection groups for the ONS 15454: ported and portless. Ported 1:N
interfaces are the traditional protection groups for signals electrically terminated on the shelf assembly.
Portless 1:N interfaces are signals received through an electrical synchronous transport signal (STS)
through the cross-connect card. The DS3XM-12 card supports portless as well as traditional ported
deployments. Table 7-1 on page 7-3 outlines the 1:N configurations supported by each electrical card
type.
The following rules apply to ported 1:N protection groups in the ONS 15454:
• Working and protect card groups must reside in the same card bank (Side A or Side B).
• The 1:N protect card must reside in Slot 3 for Side A and Slot 15 for Side B.
• Working cards can sit on either or both sides of the protect card.
The following rules apply to portless 1:N protection groups in the ONS 15454:
• Working and protect card groups can reside in the same card bank or different card banks (Side A
or Side B).
• The 1:N protect card can be installed in either Slot 3 or Slot 15 and protect working cards in both
card banks.
• Working cards can sit on either or both sides of the protect card.
The ONS 15454 supports 1:N equipment protection for all add-drop multiplexer (ADM) configurations
(ring, linear, and terminal), as specified by Telcordia GR-253-CORE. For detailed procedures for setting
up DS-1 and DS-3 protection groups, refer to the Cisco ONS 15454 Procedure Guide.
3. A high-density electrical card inserted in Slot 16 restricts the use of Slot 14 to optical, data, or storage cards.
4. A high-density electrical card inserted in Slot 17 restricts the use of Slots 12 and 13 to optical, data, or storage cards.
5. A high-density electrical card inserted in Slot 1 restricts the use of Slots 5 and 6 to optical, data, or storage cards.
6. A high-density electrical card inserted in Slot 2 restricts the use of Slots 4 and 6 to optical, data, or storage cards.
7. A high-density electrical card inserted in Slot 16 restricts the use of Slot 14 to optical, data, or storage cards.
8. A high-density electrical card inserted in Slot 17 restricts the use of Slots 12 and 13 to optical, data, or storage cards.
9. Portless DS-3 Transmux operation does not terminate the DS-3 signal on the EIA panel.