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Cisco Bug: CSCuo58538 - ANR should be enabled by default

Last Modified

Jun 07, 2018

Products (1)

  • Cisco Carrier Routing System

Known Affected Releases

4.2.4.BASE 5.1.3.BASE

Description (partial)

Symptom:
Some customers have reported issues where traffic through the router was affected triggered by an isolated hardware issue on the RP or linecards. The hardware failure condition may have been caused by a transient issue or a condition where the forwarding ASICs or the RP CPU complex had a hard fault resulting in data path outage. However, the isolated failure of a LC or an RP should not affect any transit traffic through the router, especially when the remaining linecards or the fabric sub-system does not show any error conditions. 

The identification of the bad hardware is a time consuming effort and at times it is not clear whether multiple nodes might have been affected. The stability is restored when the bad hardware is shut down or removed from the system but this is usually after a prolonged outage where end-customer traffic is dropped. Often times, focus on service restoration implies that troubleshooting information is not collected and the root cause remains elusive or unknown. Very rarely, we have been able to recreate the problems during EFA but the success rate is low. Customers expect the CRS to be a carrier class product and therefore do not accept isolated hardware failure as an excuse for the single point of failure event.

Conditions:
Faulty HW
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