implementing some ad-hoc patches I did yesterday to get it going

debian/wit-network-config.postinst

@@ -89,6 +89,13 @@ case "$1" in
                 local=$(dig_txt local.${ifname}.${HOSTNAME})
                 remote=$(dig_txt remote.${ifname}.${HOSTNAME})
 
+
+		## for the GRE tunnel to not have to deal with ibgp/full-mesh or reflectors prepending a private AS
+                TIER_ID=$(echo $LOOPBACKv4 | cut -d . -f 3)
+                NODE_ID=$(echo $LOOPBACKv4 | cut -d . -f 4)
+                FRR_GRE_ASN="4200$(printf "%03d" $TIER_ID)$(printf "%03d" $NODE_ID)"
+
+
                 ## build FRR interface config to enable ND adv for ipv6 unmanaged
                 FRR_IFS="${FRR_IFS}interface $ifname\n"
                 FRR_IFS="${FRR_IFS} description $ifalias\n"
@@ -284,6 +291,7 @@ case "$1" in
                 -e "s/^!!! FRR_IPV6_CUSTOMERS_PFLIST/$FRR_IPV6_CUSTOMERS_PFLIST/"  \
                 -e "s/^!!! FRR_IPV4_LOOPBACK_PFLIST/$FRR_IPV4_LOOPBACK_PFLIST/"  \
                 -e "s/^!!! FRR_IPV6_LOOPBACK_PFLIST/$FRR_IPV6_LOOPBACK_PFLIST/"  \
+                -e "s/FRR_GRE_ASN/${FRR_GRE_ASN}/"  \
                 -e "s/FRRROUTERID/${LOOPBACKv4}/" \
                 -e "s/NODEASN/${NODEASN}/"  \
                 $FRRCONFIG

files/frr.conf.wit

@@ -27,7 +27,7 @@ router bgp NODEASN
  neighbor feth2 interface peer-group fabric
  !!!  neighbor GRE peer-group
  !!!  neighbor GRE remote-as external
- !!!  neighbor GRE local-as NODEDEFAULTASN
+ !!!  neighbor GRE local-as FRR_GRE_ASN
  !!!  neighbor GRE password wIt2Go
  !!!  neighbor GRE ebgp-multihop 255
  !!!  neighbor eBGPv4 peer-group
@@ -189,6 +189,10 @@ route-map LOCALNETSv6 permit 5
 !!!   description "allow WIT customer IPs"
 !!!   match ip address prefix-list WITv4-CUSTOMERS
 !!!  !
+!!!  route-map FABRICv4-OUT permit 15
+!!!   description "allow WIT loopback IPs"
+!!!   match ip address prefix-list LOOPBACKv4
+!!!  !
 
 
 !!!  route-map FABRICv6-OUT permit 5