ADC SWD4573I1 Manuale Utente

You can configure the Avidia system for static load sharing, using two installed line cards. 
However, if one line card fails, the second line card takes over the functionality of the failed line 
card, and re-establishes all the connections. This can result in too heavy a traffic load on the 
second line card. To handle this, you can configure the recovery priority by traffic type (for 
example, CBR first, rt-VBR second). If you do not configure recovery priorities, the 
connections are recovered sequentially until no further resources are available. After that point, 
the remaining connections are dropped. See 

 for more 

information about static load sharing and traffic management.

When an initial call request is unsuccessful, or an existing connection fails, and the call has been 
retried the maximum configured number of times, the call request is re-routed using the other 
line card.

OC3 line cards have two physical SONET interfaces, each with a transmit and receive port. 
Under normal operation, all traffic is carried through the first interface; the second is not used. 
Automatic Protection Switching (APS) uses the second interface to provide a backup to the first.

Avidia uses 1+1 unidirectional APS. In this version of APS, the primary interface is defined as 
the working channel. The second interface is defined as the protection channel. Transmitted data 
is sent over both channels. Data is normally received through the working channel. However, if 
the working channel fails, received data automatically switches to the protection channel.

By default, APS is disabled on Avidia systems. You must enable APS for automatic switching 
to occur. See 

 (command-line interface) or 

 (Web interface) to enable APS.