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Cisco Bug: CSCus77973 - NCS6K HA Fabric Lost Packets with 5 planes

Last Modified

Aug 06, 2018

Products (1)

  • Cisco Network Convergence System 6000 Series Routers

Known Affected Releases


Description (partial)

---Start of Note Titled: Release-note---


In a multi-chassis router with one of the fabric planes shut down, line-rate 
traffic with small packets (256Bytes) suffers packet loss to the tune of 5% 
when one or more FIA devices have a reachability of less than 5 planes (30 


When all the links in the fabric are up and all planes are up, this setting 
will not have any adverse impact. But when a plane is down (bringing the 
total number of links from/to FIAs to 30) and one or more FIA devices have 
fewer than 30 links up towards them, the all-reachability vector on all FIAs 
are reduced to less than 30. In this scenario, all FIAs 
end up using a number of links less than 30 to arrive at the total credits. 
Depending on how many links are down to the affected FIA, the total credits 
could be much less than that needed for doing line-rate traffic.
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