Skip to main content

Documentation Index

Fetch the complete documentation index at: https://mintlify.com/Mats2208/MCP-Packet-Tracer/llms.txt

Use this file to discover all available pages before exploring further.

pt_validate_plan runs a structured validation pass over a TopologyPlan JSON and returns a typed result containing errors, warnings, and a validity flag. The validation engine checks multiple categories independently — device models, cable types and port conflicts, IP addressing, DHCP, routing, ACL, and NAT — and collects all issues before returning, so you see every problem in a single call rather than fixing one at a time. Each error carries a machine-readable error_code from a fixed set of 34 codes, a human-readable message, the affected device, and a suggestion for how to fix it.

​
Parameter

​
plan_json
string
required
The TopologyPlan serialized as a JSON string — the direct output of pt_plan_topology. The tool first checks that the JSON is parseable and contains a non-empty devices array before running any domain validation.

​
Returns

​
valid
boolean
true when there are zero errors (warnings are allowed). false if any error was found.
​
error_count
integer
Total number of errors in the plan.
​
warning_count
integer
Total number of warnings in the plan.
​
errors
array
List of error objects. Each object has: error_code (string), device (string), message (string), suggestion (string).
​
warnings
array
List of warning objects with the same shape as errors. Warnings do not make the plan invalid but indicate configuration issues worth reviewing.
​
summary
string
A one-line human-readable summary: "✅ Plan válido. Sin errores." or "❌ Plan con N error(es).".

​
34 Error Codes

The validator reports errors using a fixed taxonomy of ErrorCode values. The table below groups them by category. In addition, two special pre-validation codes — INVALID_JSON (unparseable input) and EMPTY_PLAN (missing or empty devices array) — are returned before any domain checks run.

​
Device Errors

Error CodeMeaning
UNKNOWN_DEVICE_MODELA device references a model name that does not exist in the 74-model catalog
DUPLICATE_DEVICE_NAMETwo or more devices share the same name
INSUFFICIENT_PORTSA router or switch does not have enough physical ports for all its declared links
Error CodeMeaning
DEVICE_NOT_FOUNDA link references a device name that does not exist in the plan
INVALID_PORTA link references a port name that does not exist on the device’s model
PORT_ALREADY_USEDThe same port appears in more than one link on the same device
INVALID_CABLE_TYPEThe cable type specified for a link is not one of the 15 supported PT cable types

​
IP Errors

Error CodeMeaning
INVALID_IP_ADDRESSAn IP address on a device interface is malformed or not a valid IPv4 address
SUBNET_OVERLAPTwo or more LAN or link subnets have overlapping address ranges
IP_CONFLICTTwo devices share the same IP address

​
DHCP Errors

Error CodeMeaning
DHCP_ROUTER_NOT_FOUNDA DHCP pool references a router name that does not exist in the plan
DHCP_GATEWAY_MISMATCHA DHCP pool’s gateway IP does not match any interface on its router (reported as a warning, not an error)

​
Routing Errors

Error CodeMeaning
UNSUPPORTED_ROUTING_PROTOCOLThe routing protocol value is not one of static, ospf, eigrp, rip, none
TEMPLATE_CONSTRAINT_VIOLATIONThe number of routers or switches violates a constraint of the selected template

​
ACL Errors

Error CodeMeaning
ACL_ROUTER_NOT_FOUNDAn ACL references a router not present in the active topology
ACL_INTERFACE_NOT_FOUNDAn ACL binding references an interface not found on the router
ACL_INVALID_NUMBERThe ACL number is outside IOS valid ranges (standard: 1–99, extended: 100–199)
ACL_TYPE_MISMATCHThe ACL number range contradicts the declared ACL type
ACL_DUPLICATE_SEQUENCETwo or more ACL entries share the same sequence number
ACL_INVALID_WILDCARDA wildcard mask in an ACL entry is not a valid inverse mask
ACL_INVALID_PROTOCOL_FOR_PORTSPort operators (eq, range) are used with a protocol that does not support ports
ACL_UNREACHABLE_RULEA permit any or deny any rule makes subsequent rules unreachable
ACL_EMPTYAn ACL was declared with no entries

​
NAT Errors

Error CodeMeaning
NAT_ROUTER_NOT_FOUNDNAT config references a router not in the topology
NAT_INTERFACE_NOT_FOUNDInside or outside interface not found on the router
NAT_INVALID_IPA static NAT mapping contains a malformed IP address
NAT_INVALID_NETMASKA NAT pool or static mapping contains an invalid subnet mask
NAT_POOL_RANGE_INVALIDThe NAT pool start IP is higher than the pool end IP
NAT_MISSING_INSIDE_NETWORKSDynamic or PAT mode requires inside_networks but none were provided
NAT_MISSING_STATIC_MAPPINGSStatic NAT mode requires static_mappings but none were provided
NAT_MISSING_POOLDynamic NAT mode requires a named pool but none was defined
NAT_SAME_INTERFACEInside and outside interfaces are the same interface

​
General Errors

Error CodeMeaning
INVALID_INTERFACE_ASSIGNMENTAn interface assignment is structurally invalid
VALIDATION_ERRORA catch-all for validation failures that do not fit a more specific category

​
Example Validation Error Response

{
  "valid": false,
  "error_count": 2,
  "warning_count": 1,
  "errors": [
    {
      "error_code": "INVALID_PORT",
      "device": "R1",
      "message": "Port 'GigabitEthernet0/3' does not exist on model '1941' (has 2 GigabitEthernet ports)",
      "suggestion": "Use GigabitEthernet0/0 or GigabitEthernet0/1, or upgrade the router model to 2911"
    },
    {
      "error_code": "PORT_ALREADY_USED",
      "device": "R2",
      "message": "Port 'GigabitEthernet0/0' is used in more than one link",
      "suggestion": "Assign the second link to GigabitEthernet0/1"
    }
  ],
  "warnings": [
    {
      "error_code": "DHCP_GATEWAY_MISMATCH",
      "device": "R1",
      "message": "DHCP pool gateway 192.168.1.1 does not match any R1 interface",
      "suggestion": "Check that the DHCP pool gateway matches the router's LAN interface IP"
    }
  ],
  "summary": "❌ Plan con 2 error(es)."
}
After receiving validation errors, use pt_fix_plan to automatically correct the most common issues — wrong cable types, insufficient ports leading to model upgrades, and invalid port reassignments. After auto-fixing, run pt_validate_plan again to confirm the plan is clean before generating scripts.

Build docs developers (and LLMs) love

Get started for freeTalk to us