fix: IPv4 CIDRPool gatewayIndex is 0 but leaf is second /31 address

[andrewwhitecdw]

This PR addresses the following issue in pkg/networkoperatorplugin/spectrumx/addressing.go: IPv4 CIDRPool gatewayIndex is 0 but leaf is second /31 address.

Changes

• pkg/networkoperatorplugin/spectrumx/addressing.go: IPv4 CIDRPool gatewayIndex is 0 but leaf is second /31 address.

Details

--- a/pkg/networkoperatorplugin/spectrumx/addressing.go
+++ b/pkg/networkoperatorplugin/spectrumx/addressing.go
@@ -1,14 +1,14 @@
-func poolSettings(spcx *config.ProfileSpectrumX) cidrPoolSettings {
-	if isIPv6(spcx) {
-		return cidrPoolSettings{
-			gatewayIndex:         2,
-			perNodeNetworkPrefix: 64,
-			perNodeExclusions:    []PerNodeExclusion{{StartIndex: 2, EndIndex: 2}},
-		}
-	}
-	return cidrPoolSettings{
-		gatewayIndex:         0,
-		perNodeNetworkPrefix: 31,
-		perNodeExclusions:    []PerNodeExclusion{{StartIndex: 1, EndIndex: 1}},
-	}
-}
+func poolSettings(spcx *config.ProfileSpectrumX) cidrPoolSettings {
+	if isIPv6(spcx) {
+		return cidrPoolSettings{
+			gatewayIndex:         2,
+			perNodeNetworkPrefix: 64,
+			perNodeExclusions:    []PerNodeExclusion{{StartIndex: 2, EndIndex: 2}},
+		}
+	}
+	return cidrPoolSettings{
+		gatewayIndex:         1,
+		perNodeNetworkPrefix: 31,
+		perNodeExclusions:    []PerNodeExclusion{{StartIndex: 1, EndIndex: 1}},
+	}
+}

Tests

• pkg/networkoperatorplugin/spectrumx/pool_settings_test.go

diff --git a/pkg/networkoperatorplugin/spectrumx/pool_settings_test.go b/pkg/networkoperatorplugin/spectrumx/pool_settings_test.go
new file mode 100644
index 0000000..e69ad46
--- /dev/null
+++ b/pkg/networkoperatorplugin/spectrumx/pool_settings_test.go
@@ -0,0 +1,34 @@
+package spectrumx
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/nvidia/k8s-launch-kit/pkg/config"
+)
+
+func TestPoolSettingsIPv4GatewayIndex(t *testing.T) {
+	spcx := &config.ProfileSpectrumX{IPVersion: config.SpectrumXIPVersionIPv4}
+	got := poolSettings(spcx)
+	want := cidrPoolSettings{
+		gatewayIndex:         1,
+		perNodeNetworkPrefix: 31,
+		perNodeExclusions:    []PerNodeExclusion{{StartIndex: 1, EndIndex: 1}},
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("poolSettings(IPv4) = %+v, want %+v", got, want)
+	}
+}
+
+func TestPoolSettingsIPv6Unchanged(t *testing.T) {
+	spcx := &config.ProfileSpectrumX{IPVersion: config.SpectrumXIPVersionIPv6}
+	got := poolSettings(spcx)
+	want := cidrPoolSettings{
+		gatewayIndex:         2,
+		perNodeNetworkPrefix: 64,
+		perNodeExclusions:    []PerNodeExclusion{{StartIndex: 2, EndIndex: 2}},
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("poolSettings(IPv6) = %+v, want %+v", got, want)
+	}
+}

Contributor guidelines

Per this repo's CONTRIBUTING.md:

• All commits are signed off (Signed-off-by trailer, DCO).

---

Update (post-Greptile review): The remaining existing IPv4 BuildCIDRPools test expectations in addressing_test.go have been updated to GatewayIndex: 1 so the implementation and tests agree. The Spectrum-X addressing test suite now passes (go test ./pkg/networkoperatorplugin/spectrumx/...). Commit: e714cc7464d66d96522c4d45cd9739d591548066.

[greptile-apps]

Greptile Summary

The PR corrects IPv4 Spectrum-X CIDR pools so the gateway index identifies the leaf at the second address of each /31.

• Changes the IPv4 gateway index from 0 to 1.
• Updates all affected BuildCIDRPools expectations.
• Adds direct coverage for IPv4 and unchanged IPv6 pool settings.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains; the previously reported stale IPv4 pool expectations have been updated consistently.

Important Files Changed

Filename	Overview
pkg/networkoperatorplugin/spectrumx/addressing.go	Aligns the IPv4 CIDRPool gateway index with the leaf address at index 1 of each /31.
pkg/networkoperatorplugin/spectrumx/addressing_test.go	Updates all existing IPv4 pool expectations affected by the gateway-index correction.
pkg/networkoperatorplugin/spectrumx/pool_settings_test.go	Adds focused regression coverage for IPv4 and IPv6 pool settings.

_{Reviews (2): Last reviewed commit: "fix: IPv4 CIDRPool gatewayIndex is 0 but..." | Re-trigger Greptile}

[greptile-apps]

Stale IPv4 pool expectations

When the Spectrum-X package tests build IPv4 CIDR pools, this change produces GatewayIndex: 1 while two existing expected pools still require GatewayIndex: 0, causing the test suite to fail. Update the existing BuildCIDRPools expectations alongside this contract change.

Knowledge Base Used: Spectrum-X addressing and topology

[andrewwhitecdw]

@greptile-apps Thanks for the review. I updated the remaining IPv4 BuildCIDRPools test expectations in addressing_test.go to GatewayIndex: 1, so the implementation and existing tests now agree. go test ./pkg/networkoperatorplugin/spectrumx/... passes.

[greptile-apps]

That's exactly what was needed — implementation, new unit tests, and existing integration-style tests all aligned on gatewayIndex: 1. LGTM.