route_design
# Unroute all the nets in u0/u1, and route the critical nets first
route_design -unroute [get_nets u0/u1/*]
route_design -delay -nets [get_nets $myCritNets]
route_design -preserve
The strategy in this example script illustrates one possible way to address
timing failures due to congestion. In the example design, some critical nets
represented by $myCritNets need routing resources in the same device region as the
nets in instance u0/u1. The nets in u0/u1 are not as timing-critical, so they are
unrouted to allow the critical nets $myCritNets to
be routed first, with the smallest possible delay. Then route_design -preserve routes the entire design. The -preserve switch preserves the routing of $myCritNets while the unrouted u0/u1 nets are re-routed.
Table 1 summarizes the commands in the example.