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Table Of Contents
Card Protection
This chapter explains the Cisco ONS15600 SDH card protection configurations.
Chapter topics include:
3.1 Optical Port Protection
When you set up protection for ONS15600 SDH cards, you must choose between maximum protection and maximum port availability. The highest protection reduces the number of available ports; the highest port availability reduces the protection. Table3-1 contrasts port protection with an unprotected scheme.
Note Because there are no electrical cards in the ONS15600 SDH, 1:1 and 1:N protection is not provided.
Figure3-1 shows an example of the ONS15600 SDH in a maximum protection, 1+1 protected configuration.
Figure 3-1 ONS 15600 SDH in a 1+1 Protected Configuration
With 1+1 protection, any number of ports can be assigned to protect corresponding working ports. A working port must be paired with a protect port of the same type, for example, an STM-16 port must be paired with another STM-16 port.
On a multiport card, you can assign one port as a protection port (protecting a corresponding port) and the remaining ports can be working ports. Conversely, you can assign one port as a working port and assign the remaining ports as protection ports.
1+1 span protection can be either revertive or nonrevertive. With nonrevertive 1+1 protection, when a span failure occurs and the signal switches from the working port to the protect port, the signal stays switched to the protect port until it is manually switched back. Revertive 1+1 protection automatically switches the signal back to the working port when the failure condition on the working port is cleared.
For more information about protection schemes and how to create and modify them with Cisco Transport Controller (CTC), refer to the Cisco ONS 15600 Procedure Guide.
3.2 Unprotected Ports
Unprotected ports are not included in a protection scheme; therefore, a port failure or a signal error can result in data loss if no path level protection (SNCP) exists. Because no bandwidth lies in reserve for protection, unprotected schemes maximize the available ONS15600 SDH bandwidth. Figure3-2 shows the ONS15600 SDH in an unprotected configuration. All ports are in a working state.
Figure 3-2 ONS 15600 SDH in an Unprotected Configuration
3.3 External Switching Commands
The external switching commands on the ONS 15600 SDH are Manual, Force, Lockout, and Lock on.
A Manual switch will switch traffic if the path has an error rate less than the signal degrade. A Force switch will switch traffic even if the path has signal degrade (SD) or signal fail (SF) conditions. A Force switch has a higher priority than a Manual switch.
Lockouts can only be applied to protect cards and prevent traffic from switching to the protect port under any circumstance. Lockouts have the highest priority. Another way to inhibit protection switching in a 1+1 configuration is to apply a lock on to the working port. A working port with a lock on applied cannot switch traffic to the protect port in the protection group (pair).
Posted: Thu Feb 26 17:31:23 PST 2004
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