diff --git a/etc/ngcp-ngcpcfg/ngcpcfg.cfg b/etc/ngcp-ngcpcfg/ngcpcfg.cfg
index 2a1923a4..3a6a004d 100644
--- a/etc/ngcp-ngcpcfg/ngcpcfg.cfg
+++ b/etc/ngcp-ngcpcfg/ngcpcfg.cfg
@@ -30,6 +30,10 @@ TEMPLATE_POOL_BASE="${NGCPCTL_MAIN}/templates"
 # location of service definitions
 SERVICES_POOL_BASE="${NGCPCTL_MAIN}/templates"
 
+# location of sites info for templates
+SITES_DIR="${NGCPCTL_MAIN}/sites"
+SITES_CONFIG="${NGCPCTL_MAIN}/sites.yml"
+
 # location of instances info for templates
 TEMPLATE_INSTANCES="${NGCPCTL_MAIN}/instances.yml"
 
diff --git a/functions/init b/functions/init
index 4aeba970..3f7ab958 100644
--- a/functions/init
+++ b/functions/init
@@ -99,6 +99,8 @@ export LC_ALL=C
 export CONFIG_POOL
 export HOST_CONFIG
 export LOCAL_CONFIG
+export SITES_CONFIG
+export SITES_DIR
 export NGCPCTL_CONFIG
 export CONSTANTS_CONFIG
 export MAINTENANCE_CONFIG
diff --git a/helper/tt2-process b/helper/tt2-process
index 3d240c6d..f383808e 100755
--- a/helper/tt2-process
+++ b/helper/tt2-process
@@ -26,6 +26,8 @@ $TIME_FORMAT =~ s/^\+//;
 
 my $NGCPCTL_MAIN = $ENV{NGCPCTL_MAIN};
 my $TEMPLATE_POOL_BASE = $ENV{TEMPLATE_POOL_BASE};
+my $SITES_DIR = $ENV{SITES_DIR} // "$NGCPCTL_MAIN/sites";
+my $SITES_CONFIG = $ENV{SITES_CONFIG} // "$NGCPCTL_MAIN/sites.yml";
 my $CONFIG_POOL = $ENV{CONFIG_POOL} // '';
 
 my %options = (
@@ -35,6 +37,8 @@ my %options = (
 chomp $options{jobs};
 
 error("NGCPCTL_MAIN is not defined") unless $NGCPCTL_MAIN;
+error("SITES_DIR is not defined") unless $SITES_DIR;
+error("SITES_CONFIG is not defined") unless $SITES_CONFIG;
 error("TEMPLATE_POOL_BASE is not defined") unless $TEMPLATE_POOL_BASE;
 
 GetOptions(\%options,
@@ -436,14 +440,64 @@ sub merge_yml {
 sub process {
     my %options = @_;
     my $config = {};
+    my $sites = {};
 
     my $visible_jobs = $options{jobs} || 'unlimited';
     info("Building configurations with $visible_jobs concurrent jobs");
 
-    foreach my $file (@{$options{config}}) {
-        $config = merge_yml($config, $file);
+    if (-f $SITES_CONFIG && -d $SITES_DIR && -l "$SITES_DIR/current") {
+        $sites = LoadFile($SITES_CONFIG);
     }
 
+    $sites->{sites_enable} //= 'no';
+
+    if ($sites->{sites_enable} eq 'yes') {
+        info("Loading in multi-site mode");
+
+        my $current_site = readlink "$SITES_DIR/current";
+        if (not defined $current_site) {
+            error("Cannot read symlink target for $SITES_DIR/current: $!");
+        }
+        info("Current site is '$current_site'");
+
+        if (not exists $sites->{sites}{$current_site}) {
+            error("Cannot find current site $current_site in sites definitions.");
+        }
+
+        foreach my $site (sort keys %{$sites->{sites}}) {
+            foreach my $file (@{$options{config}}) {
+                my $site_file = "$SITES_DIR/$site/" . basename($file);
+
+                $sites->{sites}{$site} = merge_yml($sites->{sites}{$site}, $site_file);
+            }
+        }
+
+        # First fill the root config with the current site.
+        $config = $sites->{sites}{$current_site};
+
+        # Then fill the sites sub-trees.
+        foreach my $site (sort keys %{$sites->{sites}}) {
+            $config->{sites}{$site} = $sites->{sites}{$site};
+        }
+
+        # Create the 'current' reference.
+        $config->{sites}{current} = $config->{sites}{$current_site};
+    } else {
+        info("Loading in single-site mode");
+
+        foreach my $file (@{$options{config}}) {
+            $sites = merge_yml($sites, $file);
+        }
+
+        # First fill the root config with the current site.
+        $config = $sites;
+
+        # Create the 'current' site reference for compatibility.
+        $config->{sites}{current} = $sites;
+    }
+
+    $config->{sites_enable} = $sites->{sites_enable};
+
     my $tt = NGCP::Template->new();
     my $rc;
 
diff --git a/scripts/cat b/scripts/cat
index ed1559ce..992e74a0 100755
--- a/scripts/cat
+++ b/scripts/cat
@@ -35,7 +35,7 @@ fi
 # shellcheck disable=SC1090
 . "${FUNCTIONS}"/main
 
-CONFIG_TYPES=(config maintenance network constants)
+CONFIG_TYPES=(config maintenance sites network constants)
 
 # Get the list of config types to load.
 if [ "${#:-}" -eq 0 ]; then
@@ -49,7 +49,7 @@ for t in "${CONFIG_TYPES[@]}"; do
 done
 while [ -n "${1:-}" ]; do
   case "$1" in
-    constants|config|network|maintenance)
+    constants|config|network|maintenance|sites)
       config_types[$1]=true
       shift
       ;;
@@ -72,6 +72,9 @@ if "${config_types[config]}"; then
   configs_try+=("${HOST_CONFIG}")
   configs_try+=("${LOCAL_CONFIG}")
 fi
+if "${config_types[sites]}"; then
+  configs_try+=("${SITES_CONFIG}")
+fi
 if "${config_types[maintenance]}"; then
   configs_try+=("${MAINTENANCE_CONFIG}")
 fi
diff --git a/scripts/edit b/scripts/edit
index 19d33e5f..44ac2a2b 100755
--- a/scripts/edit
+++ b/scripts/edit
@@ -36,13 +36,25 @@ if [ "${#:-}" -ge 1 ] ; then
   if [ ! -r "${file}" ]; then
     case ${file,,} in
       1|config|config.yml)
-        file="${NGCPCTL_MAIN}/config.yml"
+        if [ -e "${SITES_DIR}/current/config.yml" ]; then
+          file="${SITES_DIR}/current/config.yml"
+        else
+          file="${NGCPCTL_MAIN}/config.yml"
+        fi
         ;;
       2|network|network.yml)
-        file="${NGCPCTL_MAIN}/network.yml"
+        if [ -e "${SITES_DIR}/current/network.yml" ]; then
+          file="${SITES_DIR}/current/network.yml"
+        else
+          file="${NGCPCTL_MAIN}/network.yml"
+        fi
         ;;
       3|constants|constants.yml)
-        file="${NGCPCTL_MAIN}/constants.yml"
+        if [ -e "${SITES_DIR}/current/constants.yml" ]; then
+          file="${SITES_DIR}/current/constants.yml"
+        else
+          file="${NGCPCTL_MAIN}/constants.yml"
+        fi
         ;;
       *)
         echo "Error: Unknown choice '${file}'. Aborting." >&2
diff --git a/t/fixtures/ngcpcfg.cfg b/t/fixtures/ngcpcfg.cfg
index fdd7a1ff..8efbdc4c 100644
--- a/t/fixtures/ngcpcfg.cfg
+++ b/t/fixtures/ngcpcfg.cfg
@@ -19,6 +19,10 @@
 # location of service definitions
 [ -n "${SERVICES_POOL_BASE:-}" ] || SERVICES_POOL_BASE="${NGCPCTL_MAIN}/templates"
 
+# location of sites info for templates
+[ -n "${SITES_DIR:-}" ] || SITES_DIR="${NGCPCTL_MAIN}/sites"
+[ -n "${SITES_CONFIG:-}" ] || SITES_CONFIG="${NGCPCTL_MAIN}/sites.yml"
+
 # timestamp format for console output
 [ -n "${TIME_FORMAT:-}" ] || TIME_FORMAT="+%F %T"
 
diff --git a/t/fixtures/ngcpcfg_carrier.cfg b/t/fixtures/ngcpcfg_carrier.cfg
index c6611553..4b345f4f 100644
--- a/t/fixtures/ngcpcfg_carrier.cfg
+++ b/t/fixtures/ngcpcfg_carrier.cfg
@@ -21,6 +21,10 @@
 # location of service definitions
 [ -n "${SERVICES_POOL_BASE:-}" ] || SERVICES_POOL_BASE="${NGCPCTL_MAIN}/templates"
 
+# location of sites info for templates
+[ -n "${SITES_DIR:-}" ] || SITES_DIR="${NGCPCTL_MAIN}/sites"
+[ -n "${SITES_CONFIG:-}" ] || SITES_CONFIG="${NGCPCTL_MAIN}/sites.yml"
+
 # timestamp format for console output
 [ -n "${TIME_FORMAT:-}" ] || TIME_FORMAT="+%F %T"
 
diff --git a/t/fixtures/ngcpcfg_carrier_instances.cfg b/t/fixtures/ngcpcfg_carrier_instances.cfg
index b02cdee6..637fd684 100644
--- a/t/fixtures/ngcpcfg_carrier_instances.cfg
+++ b/t/fixtures/ngcpcfg_carrier_instances.cfg
@@ -21,6 +21,10 @@
 # location of service definitions
 [ -n "${SERVICES_POOL_BASE:-}" ] || SERVICES_POOL_BASE="${NGCPCTL_MAIN}/templates"
 
+# location of sites info for templates
+[ -n "${SITES_DIR:-}" ] || SITES_DIR="${NGCPCTL_MAIN}/sites"
+[ -n "${SITES_CONFIG:-}" ] || SITES_CONFIG="${NGCPCTL_MAIN}/sites.yml"
+
 # location of instances info for templates
 [ -n "${TEMPLATE_INSTANCES:-}" ] || TEMPLATE_INSTANCES="${NGCPCTL_MAIN}/instances.yml"
 
diff --git a/t/fixtures/ngcpcfg_network_interfaces.cfg b/t/fixtures/ngcpcfg_network_interfaces.cfg
index 00d64c08..fa42e77d 100644
--- a/t/fixtures/ngcpcfg_network_interfaces.cfg
+++ b/t/fixtures/ngcpcfg_network_interfaces.cfg
@@ -19,6 +19,10 @@
 # location of service definitions
 [ -n "${SERVICES_POOL_BASE:-}" ] || SERVICES_POOL_BASE="${NGCPCTL_MAIN}/templates"
 
+# location of sites info for templates
+[ -n "${SITES_DIR:-}" ] || SITES_DIR="${NGCPCTL_MAIN}/sites"
+[ -n "${SITES_CONFIG:-}" ] || SITES_CONFIG="${NGCPCTL_MAIN}/sites.yml"
+
 # timestamp format for console output
 [ -n "${TIME_FORMAT:-}" ] || TIME_FORMAT="+%F %T"
 
diff --git a/t/fixtures/ngcpcfg_pro.cfg b/t/fixtures/ngcpcfg_pro.cfg
index 1a449455..761c2ca5 100644
--- a/t/fixtures/ngcpcfg_pro.cfg
+++ b/t/fixtures/ngcpcfg_pro.cfg
@@ -21,6 +21,10 @@
 # location of service definitions
 [ -n "${SERVICES_POOL_BASE:-}" ] || SERVICES_POOL_BASE="${NGCPCTL_MAIN}/templates"
 
+# location of sites info for templates
+[ -n "${SITES_DIR:-}" ] || SITES_DIR="${NGCPCTL_MAIN}/sites"
+[ -n "${SITES_CONFIG:-}" ] || SITES_CONFIG="${NGCPCTL_MAIN}/sites.yml"
+
 # timestamp format for console output
 [ -n "${TIME_FORMAT:-}" ] || TIME_FORMAT="+%F %T"
 
diff --git a/t/fixtures/ngcpcfg_pro_instances.cfg b/t/fixtures/ngcpcfg_pro_instances.cfg
index 9b4eb581..3c3980dd 100644
--- a/t/fixtures/ngcpcfg_pro_instances.cfg
+++ b/t/fixtures/ngcpcfg_pro_instances.cfg
@@ -21,6 +21,10 @@
 # location of service definitions
 [ -n "${SERVICES_POOL_BASE:-}" ] || SERVICES_POOL_BASE="${NGCPCTL_MAIN}/templates"
 
+# location of sites info for templates
+[ -n "${SITES_DIR:-}" ] || SITES_DIR="${NGCPCTL_MAIN}/sites"
+[ -n "${SITES_CONFIG:-}" ] || SITES_CONFIG="${NGCPCTL_MAIN}/sites.yml"
+
 # timestamp format for console output
 [ -n "${TIME_FORMAT:-}" ] || TIME_FORMAT="+%F %T"
 
diff --git a/t/fixtures/programs.py b/t/fixtures/programs.py
index 57811ad8..eaecad5a 100644
--- a/t/fixtures/programs.py
+++ b/t/fixtures/programs.py
@@ -25,6 +25,8 @@ CFG_KEYS = [
     "PAIR_CONFIG",
     "HOST_CONFIG",
     "LOCAL_CONFIG",
+    "SITES_DIR",
+    "SITES_CONFIG",
     "CONSTANTS_CONFIG",
     "MAINTENANCE_CONFIG",
     "NETWORK_CONFIG",
diff --git a/t/fixtures/read_cfg.sh b/t/fixtures/read_cfg.sh
index af0e86ec..b42fa4bb 100755
--- a/t/fixtures/read_cfg.sh
+++ b/t/fixtures/read_cfg.sh
@@ -26,6 +26,10 @@ echo "TEMPLATE_POOL_BASE=${TEMPLATE_POOL_BASE:-}"
 # location of service definitions
 echo "SERVICES_POOL_BASE=${SERVICES_POOL_BASE:-}"
 
+# location of sites info for templates
+echo "SITES_DIR=${SITES_DIR:-}"
+echo "SITES_CONFIG=${SITES_CONFIG:-}"
+
 # location of instances info for templates
 echo "TEMPLATE_INSTANCES=${TEMPLATE_INSTANCES:-}"