| name | gateway-diagnostics |
| description | Show and ping the gateway of a network interface, on a Kubernetes node or inside a pod's network namespace. Auto-detects the gateway from the routing table (ip -j route), reports interface type (RoCE / Ethernet / IB), and tests reachability with ping. Use for default-route / gateway questions, network reachability checks, RoCE/RDMA data-path validation, and "can this node/pod reach its gateway" investigations. |
Gateway Diagnostics
Inspect and test the gateway of a network interface. Two operations, one
script each; both run identically on a node or inside a pod — the only
difference is how you launch them (see Targets below).
Router
| Need | Action |
|---|
| See the gateway / default route for an interface (with TYPE) | scripts/show-gateway.sh |
| Test whether the gateway is reachable | scripts/ping-gateway.sh |
| Target is a node (or a bound SSH host) | run directly — see Node target |
| Target is a pod | resolve the netns first — see Pod target |
| Switchdev PF caveat, or what RoCE/Ethernet/IB means | read references/switchdev-and-interface-types.md |
Targets
Node target
Prefer host_script when the node is a bound SSH host (check host_list) — it
runs over SSH with no debug pod. Fall back to node_script otherwise. Both take
the same skill / script / args.
host_script: host="<host>", skill="gateway-diagnostics", script="show-gateway.sh", args="<args>"
node_script: node="<node>", skill="gateway-diagnostics", script="show-gateway.sh", args="<args>"
Pod target
Runs in the pod's network namespace using host tools. Two steps:
- Resolve the pod's network namespace:
resolve_pod_netns: pod="<pod>", namespace="<ns>"
- Run the script with the returned node and netns:
node_script: node="<node>", netns="<netns>", skill="gateway-diagnostics", script="ping-gateway.sh", args="<args>"
The script does not enter the namespace itself — node_script does that via
the netns= param. The same script file serves both node and pod targets.
Parameters
show-gateway.sh
| Parameter | Required | Description |
|---|
--interface IFACE | no | Network interface name. If omitted, shows all. |
--json | no | Output in JSON format (adds a type field per gateway). |
ping-gateway.sh
| Parameter | Required | Description |
|---|
--interface IFACE | yes | Network interface to find the gateway for |
--source-ip | no | flag — auto-detect IP from the interface, use as ping source (-I <ip>) |
--source-dev | no | flag — use the interface name as ping source (-I <iface>) |
--count N | no | Number of ping packets (default: 3) |
--source-ip and --source-dev are mutually exclusive flags (no value needed).
Examples
Show all gateways on a node:
node_script: node="nodepool-061", skill="gateway-diagnostics", script="show-gateway.sh"
Show one interface's gateway on a bound host:
host_script: host="nodepool-061", skill="gateway-diagnostics", script="show-gateway.sh", args="--interface eth0"
Ping a node's gateway, sourcing from the interface IP:
node_script: node="nodepool-061", skill="gateway-diagnostics", script="ping-gateway.sh", args="--interface bond0 --source-ip"
Show / ping a pod's gateway (resolve netns first):
resolve_pod_netns: pod="rdma-pod", namespace="rdma-test"
→ node="worker-1", netns="abc123"
node_script: node="worker-1", netns="abc123", skill="gateway-diagnostics", script="show-gateway.sh", args="--interface net1 --json"
node_script: node="worker-1", netns="abc123", skill="gateway-diagnostics", script="ping-gateway.sh", args="--interface net1 --source-dev"
Interface types & switchdev
The output includes a TYPE column (RoCE / Ethernet / IB). If a target interface
is a PF in switchdev mode, gateway routes are not meaningful and ping will
always fail — this is expected, not a network problem. For the detection logic
and what to do instead (use a RoCE pod + the pod target), read
references/switchdev-and-interface-types.md.
