If you’ve been working with the NSX-T API and noticed that the route_type returned in the forwarding table API request is only showing as "route", you’re not alone. According to the documentation, you should expect more specific values for route_type, such as "c" for connected routes, "o" for OSPF routes, or "b" for BGP routes. So why is the API returning just "route"?
The Issue at Hand
When querying the forwarding table for a Tier-1 router in NSX-T, a typical GET request to the following API endpoint:
GET https://<nsx-manager-ip>/policy/api/v1/infra/tier-1s/T1-test2/forwarding-tablereturns something like this:
"route_entries": [
{
"route_type": "route",
"network": "10.60.1.9/24",
"admin_distance": 0,
"next_hop": "",
"lr_component_type": "SERVICE_ROUTER_TIER1"
}
]
However, according to the documentation, you should be expecting route types like "c" (connected), "o" (OSPF), or other types as per the routing protocol in use. In some cases, the response is simply "route", which raises the question: why does this happen?
Possible Causes
There are several potential reasons why you might only see "route" as the route_type. Let’s walk through each one:
NSX-T Version Mismatch
The behavior you’re observing could be due to a mismatch between the version of NSX-T you’re using and the version referenced in the documentation. Certain features or responses may differ across versions.
Router Configuration
The configuration of the Tier-1 router plays a big role in the API response. If you’re working with static routes (manually configured), the route_type will likely return as "route". However, if you have dynamic routing protocols like OSPF or BGP configured, you should see more specific route_type values such as "o" for OSPF or "b" for BGP.
Dynamic Routing Protocols Disabled
If dynamic routing protocols (e.g., OSPF, BGP) are not enabled, all routes will return as "route". Make sure that these protocols are properly configured and active if you expect to see more detailed route types.
Limitations of the /forwarding-table API
The /forwarding-table API endpoint may not provide the full range of route types you’re expecting. In some cases, this endpoint may only return basic information. For a more comprehensive look, you might need to use additional or different API endpoints, such as /routes, which may provide more context for each route entry.
Unexpected Route Types
The behavior you’re seeing might actually be expected depending on the configuration. For example, if the Tier-1 router is only handling static routes, the route_type might naturally return as "route". This could be a limitation in the router’s configuration or the way it interacts with the API.
Troubleshooting Steps
If you’re encountering this issue, it’s time to run a few checks to better understand what’s going on. Below is a Python script you can use to query the NSX-T API and analyze the response for anomalies or inconsistencies in the route_type.
Python Script: Querying and Analyzing NSX-T Forwarding Table
This script fetches the forwarding table entries from your NSX-T manager and analyzes the route_type values.
import requests
import json
# Configuration
NSX_MANAGER = "https://<nsx-manager-ip>"
USERNAME = "<your-username>"
PASSWORD = "<your-password>"
TIER1_ROUTER = "T1-test2" # Replace with your Tier-1 router name
API_ENDPOINT = f"{NSX_MANAGER}/policy/api/v1/infra/tier-1s/{TIER1_ROUTER}/forwarding-table"
# Disable SSL warnings
import urllib3
urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
def fetch_forwarding_table():
try:
# API Call
response = requests.get(
API_ENDPOINT,
auth=(USERNAME, PASSWORD),
verify=False # Use verify=True with valid certificates
)
if response.status_code == 200:
data = response.json()
analyze_response(data)
else:
print(f"Failed to fetch data. Status Code: {response.status_code}")
print("Response:", response.text)
except Exception as e:
print(f"Error during API call: {e}")
def analyze_response(data):
if "route_entries" not in data:
print("No route_entries found in the response.")
return
route_entries = data["route_entries"]
print(f"Found {len(route_entries)} route entries.\n")
for idx, entry in enumerate(route_entries, start=1):
print(f"Route Entry {idx}:")
print(f" Network: {entry.get('network')}")
print(f" Route Type: {entry.get('route_type')}")
print(f" Admin Distance: {entry.get('admin_distance')}")
print(f" Next Hop: {entry.get('next_hop', 'N/A')}")
print(f" Component Type: {entry.get('lr_component_type', 'N/A')}")
print("-" * 40)
# Check for unexpected route types
unexpected_route_types = [
entry for entry in route_entries if entry.get("route_type") == "route"
]
if unexpected_route_types:
print("\nRoutes with 'route_type' as 'route' found:")
for entry in unexpected_route_types:
print(f" Network: {entry.get('network')}, Route Type: {entry.get('route_type')}")
else:
print("\nNo unexpected route types detected.")
if __name__ == "__main__":
fetch_forwarding_table()
How the Script Helps
API Call: It makes a GET request to fetch the forwarding table for the Tier-1 router.
Response Analysis: It checks for the route_entries and prints key details, such as network, route_type, admin_distance, and next_hop.
Unexpected Route Types: It specifically checks for entries where the route_type is "route", so you can investigate them further.
Error Handling: It also handles common API errors and will help you spot any potential problems in the request.
