AR# 5686

1.5i XC4000XL PAR - Router fails to meet timing on TBUF nets, but re-route is successful.

Description

Cases have been seen where PAR failed to meet timing on paths containing
multiple driver TBUF nets, but it was noticed that re-entrant routes using PAR
or EPIC easily met timing. This problem is due to to a bug where PAR routes
and locks nets during the "pre-assignment phase", but fails to later unlock the
nets as it should.

A re-entrent route or re-route in EPIC is successful because the net locking
mechanism is gone.

Solution

This problem is fixed in vesion 2.1i, currently scheduled for 6/99. Meanwhile
the problem can be re-routed by using a re-entrant routing pass.
AR# 5686
Date 10/21/2008
Status Archive
Type General Article