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Cisco Bug: CSCtc58999 - Support for 16 import path in maximum-path command

Last Modified

Jan 31, 2014

Products (1)

  • Cisco IOS

Known Affected Releases


Description (partial)

Basic Description:
Customer requests for  increasing the limit on the paths that can be imported for 
12.0(32)SY9 throttle.
Without this fix, for the CLI "maximum-path import <number of paths>", limit is 8. 
This fix increases the limit to 16.

~90 sec outage during best path switchover even though there are multiple
redundant backup paths available with their nexthops the same as the bestpath and 
"maximum-path import 8" is configured.  8 is the upper limit for this release and the 
expected outage is ~15 sec, not ~90 sec.

When redundant paths via multiple route-reflectors to the bestpath
nexthop are available, the backup paths are utilized configuring
"maximum-path import <number of paths>". Otherwise, 
if the best path goes away, it takes a while before the scanner runs
and repopulate the VRFs with the backup paths (~90 sec). The multipath
feature does not help because the nexthop addresses are identical. 
However, when the import limit is 8 while the number of backup paths is more than 8, 
due to the non-deterministic nature of the import of the backup paths, 
there is no guarantee that the backup path with the highest preference 
will be among the paths that have been imported. If it is not, 
configuring  "maximum-paths import 8" does not help reducing the downtime to ~15 sec..
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