diff --git a/network-hypervisor/src/vl2/topology.rs b/network-hypervisor/src/vl2/topology.rs
index 3154f96f6..3defd1233 100644
--- a/network-hypervisor/src/vl2/topology.rs
+++ b/network-hypervisor/src/vl2/topology.rs
@@ -1,3 +1,61 @@
-pub struct Member {}
+use std::borrow::Cow;
 
-pub struct Topology {}
+use zerotier_utils::blob::Blob;
+use zerotier_utils::flatsortedmap::FlatSortedMap;
+
+use serde::{Deserialize, Serialize};
+
+use crate::vl1::identity::IDENTITY_FINGERPRINT_SIZE;
+use crate::vl1::inetaddress::InetAddress;
+use crate::vl2::rule::Rule;
+
+#[derive(Serialize, Deserialize, Eq, PartialEq, Clone)]
+pub struct Member<'a> {
+    #[serde(skip_serializing_if = "u64_zero")]
+    #[serde(default)]
+    pub flags: u64,
+
+    #[serde(skip_serializing_if = "cow_str_is_empty")]
+    #[serde(default)]
+    pub name: Cow<'a, str>,
+}
+
+#[derive(Serialize, Deserialize, Eq, PartialEq, Clone)]
+pub struct Topology<'a> {
+    pub timestamp: i64,
+
+    #[serde(skip_serializing_if = "cow_str_is_empty")]
+    #[serde(default)]
+    pub name: Cow<'a, str>,
+
+    #[serde(skip_serializing_if = "slice_is_empty")]
+    #[serde(default)]
+    pub rules: Cow<'a, [Rule]>,
+
+    #[serde(skip_serializing_if = "FlatSortedMap::is_empty")]
+    #[serde(default)]
+    pub dns_resolvers: FlatSortedMap<'a, Cow<'a, str>, InetAddress>,
+
+    #[serde(skip_serializing_if = "FlatSortedMap::is_empty")]
+    #[serde(default)]
+    pub dns_names: FlatSortedMap<'a, Cow<'a, str>, InetAddress>,
+
+    #[serde(skip_serializing_if = "FlatSortedMap::is_empty")]
+    #[serde(default)]
+    pub members: FlatSortedMap<'a, Blob<IDENTITY_FINGERPRINT_SIZE>, Member<'a>>,
+}
+
+#[inline(always)]
+fn u64_zero(i: &u64) -> bool {
+    *i == 0
+}
+
+#[inline(always)]
+fn cow_str_is_empty<'a>(s: &Cow<'a, str>) -> bool {
+    s.is_empty()
+}
+
+#[inline(always)]
+fn slice_is_empty<T, S: AsRef<[T]>>(x: &S) -> bool {
+    x.as_ref().is_empty()
+}
diff --git a/network-hypervisor/src/vl2/v1/networkconfig.rs b/network-hypervisor/src/vl2/v1/networkconfig.rs
index d4ae5193b..0e114fc0a 100644
--- a/network-hypervisor/src/vl2/v1/networkconfig.rs
+++ b/network-hypervisor/src/vl2/v1/networkconfig.rs
@@ -31,11 +31,6 @@ pub struct NetworkConfig {
     #[serde(default)]
     pub name: String,
 
-    /// A human-readable message for members of this network (V2 only)
-    #[serde(skip_serializing_if = "String::is_empty")]
-    #[serde(default)]
-    pub motd: String,
-
     /// True if network has access control (the default)
     pub private: bool,
 
@@ -95,7 +90,6 @@ impl NetworkConfig {
             network_id,
             issued_to,
             name: String::new(),
-            motd: String::new(),
             private: true,
             timestamp: 0,
             mtu: 0,
diff --git a/utils/src/blob.rs b/utils/src/blob.rs
index b02f7902b..660b35947 100644
--- a/utils/src/blob.rs
+++ b/utils/src/blob.rs
@@ -7,6 +7,7 @@
  */
 
 use std::fmt::Debug;
+use std::hash::Hash;
 
 use serde::ser::SerializeTuple;
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
@@ -72,6 +73,27 @@ impl<const L: usize> ToString for Blob<L> {
     }
 }
 
+impl<const L: usize> PartialOrd for Blob<L> {
+    #[inline(always)]
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        self.0.partial_cmp(&other.0)
+    }
+}
+
+impl<const L: usize> Ord for Blob<L> {
+    #[inline(always)]
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        self.0.cmp(&other.0)
+    }
+}
+
+impl<const L: usize> Hash for Blob<L> {
+    #[inline(always)]
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        self.0.hash(state);
+    }
+}
+
 impl<const L: usize> Debug for Blob<L> {
     #[inline]
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
@@ -118,7 +140,7 @@ impl<'de, const L: usize> serde::de::Visitor<'de> for BlobVisitor<L> {
 
 impl<'de, const L: usize> Deserialize<'de> for Blob<L> {
     #[inline]
-    fn deserialize<D>(deserializer: D) -> Result<Blob<L>, D::Error>
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: Deserializer<'de>,
     {
diff --git a/utils/src/flatsortedmap.rs b/utils/src/flatsortedmap.rs
new file mode 100644
index 000000000..d05e62b3e
--- /dev/null
+++ b/utils/src/flatsortedmap.rs
@@ -0,0 +1,86 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * (c) ZeroTier, Inc.
+ * https://www.zerotier.com/
+ */
+
+use std::borrow::Cow;
+use std::iter::{FromIterator, Iterator};
+
+use serde::{Deserialize, Serialize};
+
+/// A simple flat sorted map backed by a vector and binary search.
+///
+/// This doesn't support gradual adding of keys or removal of keys, but only construction
+/// from an iterator of keys and values. It also implements Serialize and Deserialize and
+/// is mainly intended for memory and space efficient serializable lookup tables.
+///
+/// If the iterator supplies more than one key with different values, which of these is
+/// included is undefined.
+#[derive(Serialize, Deserialize, PartialEq, Eq, Clone)]
+#[repr(transparent)]
+pub struct FlatSortedMap<'a, K: Eq + Ord + Clone, V: Clone>(Cow<'a, [(K, V)]>);
+
+impl<'a, K: Eq + Ord + Clone, V: Clone> FromIterator<(K, V)> for FlatSortedMap<'a, K, V> {
+    #[inline]
+    fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> Self {
+        let mut tmp = Vec::from_iter(iter);
+        tmp.sort_unstable_by(|a, b| a.0.cmp(&b.0));
+        tmp.dedup_by(|a, b| a.0.eq(&b.0));
+        Self(Cow::Owned(tmp))
+    }
+}
+
+impl<'a, K: Eq + Ord + Clone, V: Clone> Default for FlatSortedMap<'a, K, V> {
+    #[inline(always)]
+    fn default() -> Self {
+        Self(Cow::Owned(Vec::new()))
+    }
+}
+
+impl<'a, K: Eq + Ord + Clone, V: Clone> FlatSortedMap<'a, K, V> {
+    #[inline]
+    pub fn get(&self, k: &K) -> Option<&V> {
+        if let Ok(idx) = self.0.binary_search_by(|a| a.0.cmp(k)) {
+            Some(unsafe { &self.0.get_unchecked(idx).1 })
+        } else {
+            None
+        }
+    }
+
+    #[inline]
+    pub fn contains(&self, k: &K) -> bool {
+        self.0.binary_search_by(|a| a.0.cmp(k)).is_ok()
+    }
+
+    /// Returns true if this map is valid, meaning that it contains only one of each key and is sorted.
+    #[inline]
+    pub fn is_valid(&self) -> bool {
+        let l = self.0.len();
+        if l > 1 {
+            for i in 1..l {
+                if unsafe { !self.0.get_unchecked(i - 1).0.cmp(&self.0.get_unchecked(i).0).is_lt() } {
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
+
+    #[inline(always)]
+    pub fn iter(&self) -> impl Iterator<Item = &(K, V)> {
+        self.0.iter()
+    }
+
+    #[inline(always)]
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    #[inline(always)]
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+}
diff --git a/utils/src/lib.rs b/utils/src/lib.rs
index 8f211d91e..cb1e278e9 100644
--- a/utils/src/lib.rs
+++ b/utils/src/lib.rs
@@ -14,6 +14,7 @@ pub mod dictionary;
 pub mod error;
 #[allow(unused)]
 pub mod exitcode;
+pub mod flatsortedmap;
 pub mod gate;
 pub mod gatherarray;
 pub mod hex;