diff --git a/cluster/gce/config-common.sh b/cluster/gce/config-common.sh
index 438e2192746..572a4ef452e 100644
--- a/cluster/gce/config-common.sh
+++ b/cluster/gce/config-common.sh
@@ -36,6 +36,25 @@ function get-master-size {
   echo "${suggested_master_size}"
 }
 
+function get-node-ip-range {
+  if [[ -n "${NODE_IP_RANGE:-}" ]]; then
+    >&2 echo "Using user provided NODE_IP_RANGE: ${NODE_IP_RANGE}"
+    echo "${NODE_IP_RANGE}"
+    return
+  fi
+  local suggested_range="10.40.0.0/22"
+  if [[ "${NUM_NODES}" -gt 1000 ]]; then
+    suggested_range="10.40.0.0/21"
+  fi
+  if [[ "${NUM_NODES}" -gt 2000 ]]; then
+    suggested_range="10.40.0.0/20"
+  fi
+  if [[ "${NUM_NODES}" -gt 4000 ]]; then
+    suggested_range="10.40.0.0/19"
+  fi
+  echo "${suggested_range}"
+}
+
 if [[ "${FEDERATION:-}" == true ]]; then
     NODE_SCOPES="${NODE_SCOPES:-compute-rw,monitoring,logging-write,storage-ro,https://www.googleapis.com/auth/ndev.clouddns.readwrite}"
 else
diff --git a/cluster/gce/config-default.sh b/cluster/gce/config-default.sh
index c17d5346f6d..533c91cba55 100755
--- a/cluster/gce/config-default.sh
+++ b/cluster/gce/config-default.sh
@@ -218,7 +218,7 @@ if [ ${ENABLE_IP_ALIASES} = true ]; then
   SERVICE_CLUSTER_IP_SUBNETWORK=${KUBE_GCE_SERVICE_CLUSTER_IP_SUBNETWORK:-${INSTANCE_PREFIX}-subnet-services}
   # NODE_IP_RANGE is used when ENABLE_IP_ALIASES=true. It is the primary range in
   # the subnet and is the range used for node instance IPs.
-  NODE_IP_RANGE="${NODE_IP_RANGE:-10.40.0.0/22}"
+  NODE_IP_RANGE="$(get-node-ip-range)"
   # Add to the provider custom variables.
   PROVIDER_VARS="${PROVIDER_VARS} ENABLE_IP_ALIASES"
 fi
@@ -245,7 +245,7 @@ NETWORK_POLICY_PROVIDER="${NETWORK_POLICY_PROVIDER:-none}" # calico
 # How should the kubelet configure hairpin mode?
 HAIRPIN_MODE="${HAIRPIN_MODE:-promiscuous-bridge}" # promiscuous-bridge, hairpin-veth, none
 # Optional: if set to true, kube-up will configure the cluster to run e2e tests.
-E2E_STORAGE_TEST_ENVIRONMENT=${KUBE_E2E_STORAGE_TEST_ENVIRONMENT:-false}
+E2E_STORAGE_TEST_ENVIRONMENT="${KUBE_E2E_STORAGE_TEST_ENVIRONMENT:-false}"
 
 # Evict pods whenever compute resource availability on the nodes gets below a threshold.
 EVICTION_HARD="${EVICTION_HARD:-memory.available<250Mi,nodefs.available<10%,nodefs.inodesFree<5%}"
@@ -266,4 +266,6 @@ SOFTLOCKUP_PANIC="${SOFTLOCKUP_PANIC:-false}" # true, false
 # Indicates if the values (i.e. KUBE_USER and KUBE_PASSWORD for basic
 # authentication) in metadata should be treated as canonical, and therefore disk
 # copies ought to be recreated/clobbered.
-METADATA_CLOBBERS_CONFIG=${METADATA_CLOBBERS_CONFIG:-false}
+METADATA_CLOBBERS_CONFIG="${METADATA_CLOBBERS_CONFIG:-false}"
+
+ENABLE_BIG_CLUSTER_SUBNETS="${ENABLE_BIG_CLUSTER_SUBNETS:-false}"
diff --git a/cluster/gce/config-test.sh b/cluster/gce/config-test.sh
index f76981ebb1e..0d107d106b8 100755
--- a/cluster/gce/config-test.sh
+++ b/cluster/gce/config-test.sh
@@ -91,7 +91,7 @@ CLUSTER_IP_RANGE="${CLUSTER_IP_RANGE:-10.100.0.0/14}"
 MASTER_IP_RANGE="${MASTER_IP_RANGE:-10.246.0.0/24}"
 # NODE_IP_RANGE is used when ENABLE_IP_ALIASES=true. It is the primary range in
 # the subnet and is the range used for node instance IPs.
-NODE_IP_RANGE="${NODE_IP_RANGE:-10.40.0.0/22}"
+NODE_IP_RANGE="$(get-node-ip-range)"
 
 RUNTIME_CONFIG="${KUBE_RUNTIME_CONFIG:-}"
 
@@ -315,3 +315,5 @@ ENABLE_APISERVER_ADVANCED_AUDIT="${ENABLE_APISERVER_ADVANCED_AUDIT:-true}" # tru
 if [[ "${ENABLE_APISERVER_ADVANCED_AUDIT}" == "true" ]]; then
   FEATURE_GATES="${FEATURE_GATES},AdvancedAuditing=true"
 fi
+
+ENABLE_BIG_CLUSTER_SUBNETS="${ENABLE_BIG_CLUSTER_SUBNETS:-false}"
diff --git a/cluster/gce/util.sh b/cluster/gce/util.sh
index 2d96fffcaa7..a59683a0cef 100755
--- a/cluster/gce/util.sh
+++ b/cluster/gce/util.sh
@@ -88,6 +88,8 @@ NODE_INSTANCE_PREFIX="${INSTANCE_PREFIX}-minion"
 NODE_TAGS="${NODE_TAG}"
 
 ALLOCATE_NODE_CIDRS=true
+PREEXISTING_NETWORK=false
+PREEXISTING_NETWORK_MODE=""
 
 KUBE_PROMPT_FOR_UPDATE=${KUBE_PROMPT_FOR_UPDATE:-"n"}
 # How long (in seconds) to wait for cluster initialization.
@@ -508,7 +510,11 @@ function make-gcloud-network-argument() {
     ret="${ret},aliases=pods-default:${alias_size}"
     ret="${ret} --no-can-ip-forward"
   else
-    ret="--network ${network}"
+    if [[ ${PREEXISTING_NETWORK} = "true" && "${PREEXISTING_NETWORK_MODE}" != "custom" ]]; then
+      ret="--network ${network}"
+    else
+      ret="--subnet=${network}"
+    fi
     ret="${ret} --can-ip-forward"
     if [[ -n ${address:-} ]]; then
       ret="${ret} --address ${address}"
@@ -746,6 +752,10 @@ function create-network() {
     # The network needs to be created synchronously or we have a race. The
     # firewalls can be added concurrent with instance creation.
     gcloud compute networks create --project "${PROJECT}" "${NETWORK}" --mode=auto
+  else
+    PREEXISTING_NETWORK=true
+    PREEXISTING_NETWORK_MODE="$(gcloud compute networks list ${NETWORK} --format='value(x_gcloud_mode)' || true)"
+    echo "Found existing network ${NETWORK} in ${PREEXISTING_NETWORK_MODE} mode."
   fi
 
   if ! gcloud compute firewall-rules --project "${PROJECT}" describe "${CLUSTER_NAME}-default-internal-master" &>/dev/null; then
@@ -775,10 +785,31 @@ function create-network() {
   fi
 }
 
+function expand-default-subnetwork() {
+  gcloud compute networks switch-mode "${NETWORK}" \
+    --mode custom \
+    --project "${PROJECT}" \
+    --quiet || true
+  gcloud compute networks subnets expand-ip-range "${NETWORK}" \
+    --region="${REGION}" \
+    --project "${PROJECT}" \
+    --prefix-length=19 \
+    --quiet
+}
+
 function create-subnetworks() {
   case ${ENABLE_IP_ALIASES} in
-    true) ;;
-    false) return;;
+    true) echo "IP aliases are enabled. Creating subnetworks.";;
+    false)
+      echo "IP aliases are disabled."
+      if [[ "${ENABLE_BIG_CLUSTER_SUBNETS}" = "true" ]]; then 
+        if [[  "${PREEXISTING_NETWORK}" != "true" ]]; then
+          expand-default-subnetwork
+        else
+          echo "${color_yellow}Using pre-existing network ${NETWORK}, subnets won't be expanded to /19!${color_norm}"
+        fi
+      fi
+      return;;
     *) echo "${color_red}Invalid argument to ENABLE_IP_ALIASES${color_norm}"
        exit 1;;
   esac
@@ -867,6 +898,17 @@ function delete-network() {
 
 function delete-subnetworks() {
   if [[ ${ENABLE_IP_ALIASES:-} != "true" ]]; then
+    if [[ "${ENABLE_BIG_CLUSTER_SUBNETS}" = "true" ]]; then
+      # If running in custom mode network we need to delete subnets
+      mode="$(gcloud compute networks list ${NETWORK} --format='value(x_gcloud_mode)' || true)"
+      if [[ "${mode}" == "custom" ]]; then
+        echo "Deleting default subnets..."
+        # This value should be kept in sync with number of regions.
+        local parallelism=9
+        gcloud compute networks subnets list --network="${NETWORK}" --format='value(region.basename())' | \
+          xargs -i -P ${parallelism} gcloud --quiet compute networks subnets delete "${NETWORK}" --region="{}" || true
+      fi
+    fi
     return
   fi
 
@@ -1612,9 +1654,8 @@ function kube-down() {
       "${NETWORK}-default-ssh" \
       "${NETWORK}-default-internal"  # Pre-1.5 clusters
 
-    delete-subnetworks
-
     if [[ "${KUBE_DELETE_NETWORK}" == "true" ]]; then
+      delete-subnetworks || true
       delete-network || true  # might fail if there are leaked firewall rules
     fi
 
diff --git a/cluster/kubemark/gce/config-default.sh b/cluster/kubemark/gce/config-default.sh
index 2f71696cc41..dd9df48f807 100644
--- a/cluster/kubemark/gce/config-default.sh
+++ b/cluster/kubemark/gce/config-default.sh
@@ -39,7 +39,7 @@ NODE_OS_DISTRIBUTION=${KUBE_NODE_OS_DISTRIBUTION:-debian}
 MASTER_IMAGE=${KUBE_GCE_MASTER_IMAGE:-cos-stable-59-9460-64-0}
 MASTER_IMAGE_PROJECT=${KUBE_GCE_MASTER_PROJECT:-cos-cloud}
 
-NETWORK=${KUBE_GCE_NETWORK:-default}
+NETWORK=${KUBE_GCE_NETWORK:-e2e}
 INSTANCE_PREFIX="${INSTANCE_PREFIX:-"default"}"
 MASTER_NAME="${INSTANCE_PREFIX}-kubemark-master"
 AGGREGATOR_MASTER_NAME="${INSTANCE_PREFIX}-kubemark-aggregator"
diff --git a/test/kubemark/gce/util.sh b/test/kubemark/gce/util.sh
index 6fd3372567c..149958eec71 100644
--- a/test/kubemark/gce/util.sh
+++ b/test/kubemark/gce/util.sh
@@ -80,7 +80,7 @@ function create-master-instance-with-resources {
     --image-project="${MASTER_IMAGE_PROJECT}" \
     --image "${MASTER_IMAGE}" \
     --tags "${MASTER_TAG}" \
-    --network "${NETWORK}" \
+    --subnet "${NETWORK}" \
     --scopes "storage-ro,compute-rw,logging-write" \
     --boot-disk-size "${MASTER_ROOT_DISK_SIZE}" \
     --disk "name=${MASTER_NAME}-pd,device-name=master-pd,mode=rw,boot=no,auto-delete=no"