Update gateway ipv6 to use default value, that auto detects and adds to neigh table

Author: NihaNallappagari

azure-ipam/ipam_test.go

@@ -160,7 +160,7 @@ func (c *MockCNSClient) RequestIPs(ctx context.Context, ipconfig cns.IPConfigsRe
 							PrefixLength: 120,
 						},
 						DNSServers:         nil,
-						GatewayIPv6Address: "fe80::1234:5678:9abc",
+						GatewayIPv6Address: "fe80::1", // This value will be ignored - code uses defaultV6Gateway constant instead
 					},
 					HostPrimaryIPInfo: cns.HostIPInfo{
 						Gateway:   "fe80::1234:5678:9abc",

azure-ipam/ipconfig/ipconfig.go

@@ -12,6 +12,10 @@ import (
 	"github.com/pkg/errors"
 )
 
+const (
+	defaultV6Gateway   = "fe80::1234:5678:9abc"
+)
+
 func CreateOrchestratorContext(args *cniSkel.CmdArgs) ([]byte, error) {
 	podConf, err := parsePodConf(args.Args)
 	if err != nil {
@@ -86,7 +90,7 @@ func ProcessIPConfigsResp(resp *cns.IPConfigsResponse) (*[]netip.Prefix, *[]net.
 		if podIPNet.Addr().Is4() {
 			gatewayStr = resp.PodIPInfo[i].NetworkContainerPrimaryIPConfig.GatewayIPAddress
 		} else if podIPNet.Addr().Is6() {
-			gatewayStr = resp.PodIPInfo[i].NetworkContainerPrimaryIPConfig.GatewayIPv6Address
+			gatewayStr = defaultV6Gateway
 		}
 
 		gatewayIP = net.ParseIP(gatewayStr)