November 4, 2001
When an OC192/POS-SR2 line card is interconnected to an OC192/POS-SR linecard (or other equipment with an SR interface), an overload condition can occur on the SR2 optical receiver. This problem can occur on fiber optic links of any length from 0 - 2km (the limit of an SR interface).
This problem can only occur on a fiber optic link having an SR2 interface on one end and an SR interface on the other end. No other combination of interface types will exhibit this problem, including SR2 to SR2 connections.
Less than 30% of the SR2 to SR connections in the field will exhibit this problem. However, this problem will be evident on initial turn-up and will not occur on links which have already been provisioned and are working properly. This problem is not isolated to a particular batch or serial number range of SR2 line cards (all SR2 line cards are potentially affected).
The problem symptoms will be bit errors (BIP8).
When an OC192/POS-SR2 line card is interconnected to an OC192/POS-SR linecard (or other equipment with an SR interface) the input power to the SR2 line card should be below -5dBm. The use of a 3dB attenuator on the SR2 line card's receive side will accomplish this in most cases. In cases where the launch power of the SR interface is higher than typical, a 5dB attenuator can be used.
For More Information
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