ICC2: 10. Global and early routing Cheat Sheet

This stage covers the checks around global and early routing: layer constraints, clock NDR and shield readiness, route readiness and pin access, the global_route run itself, congestion review and relief, and wire length and layer use.

Sanity check cheat sheet

One row per command card. Read left to right: the check, the command that answers it, then what a healthy result, a result to review and a hard stop look like.

Card	Check and when	Command	Healthy	Review	Hard stop
G-01	Layer constraints record Before route_global	`report_ignored_layers` `report_routing_guides`	Ignored layers and guides match the technology and routing plan, and are recorded with each run.	Layer limits set for one run and not recorded, so congestion numbers cannot be compared.	A layer range that differs from the plan, so capacity is wrong before any net is routed.
G-02	Clock NDR and shield readiness Before route_global	`check_routability -check_shield true` `check_routability -via_ladder true`	Shield and via ladder findings are empty, or each finding is understood.	Findings on nets that are frozen or intended to stay unshielded.	Clock nets with shield or ladder requirements the check reports as unmet.
G-03	Route readiness and pin access Before route_global	`check_routability` `check_legality`	No blocked ports, no out-of-boundary pins, no grid violations, and placement is legal.	Blocked ports on cells you can still move, or optional checks not enabled.	Unplaced or illegal cells, blocked pins on many instances, or incorrect via definitions.
G-04	Global route run After G-03	`route_global`	Net count matches the design, the layer range is the planned one, and the log has no errors.	Warnings about ignored or frozen nets that you have not explained.	Any error, or a run that routed only part of the nets by mistake.
G-05	Overflow and congestion After G-04	`report_congestion`	Overflow in both directions is within the project budget on every layer.	Overflow in one direction only, or a few layers dominating the total.	Overflow beyond a macro channel or pin cluster budget.
G-06	Congestion in a region After G-05	`report_congestion -rerun_global_router -boundary {<box>} -layers {<layers>}`	The region shows overflow within budget, on layers you expected.	Blocked bins with zero routing resources, which point at blockages rather than demand.	A hot region over a macro channel or pin cluster where no routing change can help.
G-07	Congestion map without routing Any time after placement	`route_global -congestion_map_only true` `report_congestion`	A map is stored, and report_congestion reads it on the next call.	Soft congestion data is absent because it was not enabled before the run.	A map made with layer limits that differ from the record.
G-08	Relief and rerun After G-05	`create_routing_guide -boundary {{<llx> <lly>} {<urx> <ury>}} -horizontal_track_utilization <pct> -vertical_track_utilization <pct>` `create_routing_blockage -boundary {{<llx> <lly>} {<urx> <ury>}} -net_types signal -layers <layer>`	Overflow falls after the change and no new hotspot appears.	The hotspot moves to a neighbouring area instead of disappearing.	Overflow stays beyond budget, or a guide or blockage is left with no record of why.
G-09	Wire length and layer use After G-04	`report_wirelength` `report_design -routing`	Wire and vias sit on the planned layers, and totals match earlier runs within expectation.	One layer carrying most of the wire while layers above it are lightly used.	Wire on layers outside the planned range.

Command cheat sheet

ICC2 commands. Angle brackets are placeholders, and values shown are examples, not project limits. A dagger (†) marks a command the notes behind this book do not fully cover; it is shown without options, so confirm it with man or help in your release.

Routing resources and layers
`report_ignored_layers`	The ignored layer settings in force.
`set_ignored_layers -min_routing_layer <layer> -max_routing_layer <layer>`	Sets the layer range for RC estimation and routing. Changes the session; record it.
`remove_ignored_layers -all`	Clears the ignored layer settings. Changes the session; record it.
`set_routing_rule <nets> -min_routing_layer <layer> -max_routing_layer <layer>`	Layer limits for chosen nets. Changes the session; record it.
Clock and net rules
`create_routing_rule <rule> -widths {<layer> <width>}`	Defines a non-default rule with chosen widths. Changes the session; record it.
`set_routing_rule -rule <rule> <nets>`	Assigns the rule to signal nets. Changes the session; record it.
`set_clock_routing_rules -rules <rule>`	Assigns the rule to clock nets. Changes the session; record it.
`set_routing_rule -clear <nets>`	Clears rules on those nets, including assigned NDRs. Changes the session; record it.
Route readiness
`check_routability`	Default pin access, boundary, grid and via definition checks. Writes check_routability.err.
`check_routability -check_shield true`	Adds the shield checks to the default set.
`check_legality`	Placement legality check, run before routing.
`check_routing_corridors <corridor>`	Checks that a corridor is contiguous and covers its pins.
Run and report global route
`route_global`	Global routing. Changes the design.
`route_global -congestion_map_only true`	Congestion map only, with no routes created.
`report_congestion`	Overflow per layer, in both the horizontal and vertical directions.
`report_wirelength`	Wire length per layer, and by direction.
`report_design -routing`	Wiring and via statistics.
Guides, blockages and corridors
`create_routing_guide -boundary {{<llx> <lly>} {<urx> <ury>}} -preferred_direction_only`	A guide forcing preferred-direction routing. Changes the design.
`create_routing_blockage -boundary {{<llx> <lly>} {<urx> <ury>}} -net_types signal -layers <layer>`	A hard routing blockage. Changes the design.
`report_routing_guides`	The guides defined.
`remove_routing_guides -all`	Removes every guide. Changes the design.
`report_routing_corridors`	The corridors defined.