diff --git a/generate-topology.nix b/generate-topology.nix
index 6162d39..bae90be 100644
--- a/generate-topology.nix
+++ b/generate-topology.nix
@@ -52,130 +52,31 @@
 
   nodesById = mapAttrs' (_: node: nameValuePair node.config.topology.id node) nixosConfigurations;
 
-  xmlAttrs = attrs: concatStringsSep " " (mapAttrsToList (n: v: "${n}=\"${v}\"") attrs);
-  font = attrs: text: "<font ${xmlAttrs attrs}>${text}</font>";
-  fontMono = {face = "JetBrains Mono";};
-  mono = font fontMono;
-  monoColor = color: font (fontMono // {inherit color;});
-
-  mkCell = cellAttrs: text: "<td ${xmlAttrs cellAttrs}>${text}</td>";
-  mapToTableRows = xs: {
-    columnOrder,
-    columns,
-    titleRow ? true,
-    titleRowColor ? colors.base0C,
-    titleRowAttrs ? {bgcolor = titleRowColor;},
-    alternateRowAttrs ? {bgcolor = colors.base03b;},
-  }:
-    concatLines (
-      optional titleRow "<tr>${concatStringsSep "" (flip map columnOrder (c: mkCell titleRowAttrs "<b>${mono columns.${c}.title}</b>"))}</tr>"
-      ++ flip imap0 xs (
-        i: x: "<tr>${concatStringsSep "" (flip map columnOrder (c:
-          mkCell
-          (optionalAttrs (pkgs.lib.mod i 2 == 1) alternateRowAttrs // (columns.${c}.cellAttrs or {}))
-          (columns.${c}.transform x.${c})))}</tr>"
-      )
-    );
-
-  mkTable = xs: settings: ''
-    <table border="0" cellborder="0" cellspacing="0" cellpadding="4" bgcolor="${colors.base03}" color="${colors.base04}">
-    ${mapToTableRows xs settings}
-    </table>
-  '';
-
-  nodeId = str: "\"${escapeXML str}\"";
   isGuestOfAny = node: any (x: elem node x.config.topology.guests) (attrValues nodesById);
   rootNodes = filterAttrs (n: _: !(isGuestOfAny n)) nodesById;
 
-  toDot = node: let
+  toD2 = node: let
     topo = node.config.topology;
+  in ''
+    ${topo.id}: |md
+    # ${topo.id}
 
-    diskTable = mkTable (attrValues topo.disks) {
-      titleRowColor = colors.base0F;
-      columnOrder = ["name"];
-      columns = {
-        name = {
-          title = "Name";
-          transform = mono;
-        };
-      };
-    };
+    ## Guests:
+    ${concatLines (map (x: "- ${x}") topo.guests)}
 
-    interfaceTable = mkTable (attrValues topo.interfaces) {
-      titleRowColor = colors.base0D;
-      columnOrder = ["name" "mac" "addresses"];
-      columns = {
-        name = {
-          title = "Name";
-          transform = x:
-            if x == null
-            then ""
-            else mono x;
-        };
-        mac = {
-          title = "MAC";
-          transform = x:
-            if x == null
-            then ""
-            else monoColor colors.base09 x;
-        };
-        addresses = {
-          title = "Addr";
-          transform = xs: mono (concatStringsSep " " xs);
-        };
-      };
-    };
-  in
-    ''
-      subgraph ${nodeId "cluster_${topo.id}"} {
-        color = "${colors.base04}";
+    ## Disks:
+    ${concatLines (mapAttrsToList (_: v: "- ${v.name}") topo.disks)}
 
-        ${nodeId topo.id} [label=<
-          <table border="0" cellborder="0" cellspacing="0" cellpadding="4" bgcolor="${colors.base03}" color="${colors.base04}">
-            <tr><td bgcolor="${colors.base08}"><b>${mono "Attribute"}</b></td><td bgcolor="${colors.base08}"><b>${mono "Value"}</b></td></tr>
-            <tr><td>${mono "id"}</td><td>${mono topo.id}</td></tr>
-            <tr><td>${mono "type"}</td><td>${mono topo.type}</td></tr>
-          </table>
-        >];
+    ## Interfaces:
+    ${concatLines (mapAttrsToList (_: v: "- ${v.name}, mac ${toString v.mac}, addrs ${toString v.addresses}, network ${toString v.network}") topo.interfaces)}
 
-        {
-          rank = "same";
-          ${nodeId "${topo.id}.disks"} [label=<
-            ${diskTable}
-          >];
-          ${nodeId "${topo.id}.interfaces"} [label=<
-            ${interfaceTable}
-          >];
-        }
+    ## Firewall Zones:
+    ${concatLines (mapAttrsToList (_: v: "- ${v.name}, mac ${toString v.mac}, addrs ${toString v.addresses}, network ${toString v.network}") topo.firewallRules)}
+    |
+  '';
 
-        ${nodeId topo.id} -> ${nodeId "${topo.id}.disks"} [label="disks", color="${colors.base05}", fontcolor="${colors.base06}"];
-        ${nodeId topo.id} -> ${nodeId "${topo.id}.interfaces"} [label="interfaces", color="${colors.base05}", fontcolor="${colors.base06}"];
-    ''
-    + optionalString (topo.guests != []) ''
-        subgraph ${nodeId "cluster_guests_${topo.id}"} {
-          color = "${colors.base04}";
-          {
-            rank = "same";
-            ${concatLines (map (guest: "${nodeId guest};") topo.guests)}
-          }
-
-          ${concatLines (map (guest: dotForNodes.${guest}) topo.guests)}
-        };
-
-        ${concatLines (map (guest: "${nodeId topo.id} -> ${nodeId guest} [color=\"${colors.base05}\"];") topo.guests)}
-      }
-    ''
-    + optionalString (!isGuestOfAny topo.id) ''
-      root -> ${nodeId topo.id} [color="${colors.base05}"];
-    '';
-
-  dotForNodes = mapAttrs' (_: node: nameValuePair node.config.topology.id (toDot node)) nodesById;
+  d2ForNodes = mapAttrs' (_: node: nameValuePair node.config.topology.id (toD2 node)) nodesById;
 in
-  pkgs.writeText "topology.dot" ''
-    digraph G {
-      graph [rankdir=TB, splines=spline, bgcolor="${colors.base00}"];
-      node [shape=plaintext, fontcolor="${colors.base06}", color="${colors.base06}"];
-
-      ${concatLines (map (x: dotForNodes.${x}) (attrNames rootNodes))}
-    }
+  pkgs.writeText "topology.d2" ''
+    ${concatLines (map (x: d2ForNodes.${x}) (attrNames rootNodes))}
   ''
diff --git a/modules/topology.nix b/modules/topology.nix
index 84f82d9..936eab2 100644
--- a/modules/topology.nix
+++ b/modules/topology.nix
@@ -19,24 +19,44 @@ in {
   options.topology = {
     id = mkOption {
       description = ''
-        The attribute name in nixosConfigurations corresponding to this host.
-        Please overwrite with a unique identifier if your hostnames are not
+        The attribute name in the given `nodes` which corresponds to this host.
+        Please overwrite it with a unique identifier if your hostnames are not
         unique or don't reflect the name you use to refer to that node.
       '';
+      default = config.networking.hostName;
+      # TODO ensure unique across the board
       type = types.str;
     };
-    guests = mkOption {
-      description = "TODO guests ids (topology.id)";
-      type = types.listOf types.str;
-      default = [];
-    };
+
     type = mkOption {
       description = "TODO";
-      type = types.enum ["normal" "microvm" "nixos-container"];
       default = "normal";
+      type = types.enum ["normal" "microvm" "nixos-container"];
     };
+
+    guests = mkOption {
+      description = "TODO guests ids (topology.node.<name>.id) ensure exists";
+      default = [];
+      type = types.listOf types.str;
+    };
+
+    disks = mkOption {
+      default = {};
+      type = types.attrsOf (types.submodule (submod: {
+        options = {
+          name = mkOption {
+            description = "The name of this disk";
+            default = submod.config._module.args.name;
+            readOnly = true;
+            type = types.str;
+          };
+        };
+      }));
+    };
+
     interfaces = mkOption {
       description = "TODO";
+      default = {};
       type = types.attrsOf (types.submodule (submod: {
         options = {
           name = mkOption {
@@ -48,30 +68,45 @@ in {
 
           mac = mkOption {
             description = "The MAC address of this interface, if known.";
-            type = types.nullOr types.str;
             default = null;
+            type = types.nullOr types.str;
           };
 
           addresses = mkOption {
             description = "The configured address(es), or a descriptive string (like DHCP).";
             type = types.listOf types.str;
           };
+
+          network = mkOption {
+            description = ''
+              The global name of the attached/spanned network.
+              If this is given, this interface can be shown in the network graph.
+            '';
+            default = null;
+            type = types.nullOr types.str;
+          };
         };
       }));
-      default = {};
     };
-    disks = mkOption {
+
+    firewallRules = mkOption {
+      description = "TODO";
+      default = {};
       type = types.attrsOf (types.submodule (submod: {
         options = {
           name = mkOption {
-            description = "The name of this disk";
+            description = "The name of this firewall rule";
             type = types.str;
             readOnly = true;
             default = submod.config._module.args.name;
           };
+
+          contents = mkOption {
+            description = "A human readable summary of this rule's effects";
+            type = types.lines;
+          };
         };
       }));
-      default = {};
     };
   };
 
@@ -89,8 +124,10 @@ in {
       disks =
         flip mapAttrs (config.disko.devices.disk or {})
         (_: _: {});
+      # TODO: zfs pools from disko / fileSystems
       # TODO: microvm shares
       # TODO: container shares
+      # TODO: OCI containers shares
 
       interfaces = let
         isNetwork = netDef: (netDef.matchConfig != {}) && (netDef.address != [] || netDef.DHCP != null);