pkgs/switches/*: don't configure null vlans

nix/pkgs/switches/3com-4200G.nix

@@ -54,7 +54,9 @@ with lib;
         builtins.split "/" netConfig.subnet4
       ) 2;
       netmask = self.lib.netmasks.${prefixLength};
-    in ''
+    in
+      if netConfig.vlan != null
+      then ''
         send "vlan ${vlan}\r"
         expect -- "-vlan${vlan}]"
         send "name ${net}\r"
@@ -70,7 +72,9 @@ with lib;
         ''}
         send "quit\r"
         expect "${hostName}]"
-    '') (sortNetsByVlan (builtins.attrNames config.site.net))
+      ''
+      else ""
+    ) (sortNetsByVlan (builtins.attrNames config.site.net))
   }
 
   ${concatMapStrings (name:

nix/pkgs/switches/HP-procurve-2824.nix

@@ -37,7 +37,7 @@ with lib;
   send "logging facility local6\r"
   expect "(config)# "
 
-  # todo ntp
+  # TODO ntp
   # timesync sntp
   # ip timep manual {#ntp#} interval 10
 
@@ -51,7 +51,9 @@ with lib;
         builtins.split "/" netConfig.subnet4
       ) 2;
       netmask = self.lib.netmasks.${prefixLength};
-    in ''    
+    in
+      if netConfig.vlan != null
+      then ''
         send "vlan ${vlan}\r"
         expect "(vlan-${vlan})#"
 
@@ -81,7 +83,9 @@ with lib;
             send "no vlan ${vlan} untagged all\r"
             expect "(config)# "
           ''}
-    '') (sortNetsByVlan (builtins.attrNames config.site.net))
+      ''
+      else ""
+    ) (sortNetsByVlan (builtins.attrNames config.site.net))
   }
 
   ${concatMapStrings (name:

nix/pkgs/switches/TL-SG3210.nix

@@ -60,7 +60,9 @@ with lib;
         builtins.split "/" netConfig.subnet4
       ) 2;
       netmask = self.lib.netmasks.${prefixLength};
-    in ''
+    in
+      if netConfig.vlan != null
+      then ''
         ${optionalString (net != "mgmt") ''
           send "vlan ${vlan}\r"
           expect "(config-vlan)#"
@@ -80,6 +82,7 @@ with lib;
         send "exit\r"
         expect "(config)#"
       ''
+      else ""
   ) (sortNetsByVlan (builtins.attrNames config.site.net))}
 
   ${concatMapStrings (name:

nix/pkgs/switches/linksys-srw2048.nix

@@ -33,21 +33,35 @@ with lib;
   send "vlan database\r"
   expect "(config-vlan)# "
 
-  ${concatMapStrings (net: ''
-    send "vlan ${toString config.site.net.${net}.vlan}\r"
+  ${concatMapStrings (net:
+    let
+      netConfig = config.site.net.${net};
+    in
+      if netConfig.vlan != null
+      then ''
+        send "vlan ${toString netConfig.vlan}\r"
         expect "(config-vlan)#"
-  '') (sortNetsByVlan (builtins.attrNames config.site.net))}
+      ''
+      else ""
+  ) (sortNetsByVlan (builtins.attrNames config.site.net))}
   send "exit\r"
   expect "(config)#"
 
-  ${concatMapStrings (net: ''
+  ${concatMapStrings (net:
+    let
+      netConfig = config.site.net.${net};
+    in
+      if netConfig.vlan != null
+      then ''
         send "interface vlan ${toString config.site.net.${net}.vlan}\r"
         expect "(config-if)#"
         send "name ${net}\r"
         expect "(config-if)#"
         send "exit\r"
         expect "(config)#"
-  '') (sortNetsByVlan (builtins.attrNames config.site.net))}
+      ''
+      else ""
+  ) (sortNetsByVlan (builtins.attrNames config.site.net))}
 
   ${concatMapStrings (name:
     let