IPv4 prefixes shouldn't be sent by default over IPv6 session with FRR. (

#905)

RB=
G=lnos-reviewers
R=ntrianta,rjonnadu,rmolina,sfardeen,zxu
A=

dockers/docker-fpm-frr/bgpd.conf.j2

@@ -21,6 +21,7 @@ log facility local4
 router bgp {{ DEVICE_METADATA['localhost']['bgp_asn'] }}
   bgp log-neighbor-changes
   bgp bestpath as-path multipath-relax
+  no bgp default ipv4-unicast
 {# TODO: use lo[0] for backward compatibility, will revisit the case with multiple lo interfaces #}
   bgp router-id {{ minigraph_lo_interfaces[0]['addr'] }}
 {# advertise loopback #}
@@ -53,6 +54,12 @@ router bgp {{ DEVICE_METADATA['localhost']['bgp_asn'] }}
 {% if minigraph_devices[inventory_hostname]['type'] == 'ToRRouter' %}
   neighbor {{ neighbor_addr }} allowas-in 1
 {% endif %}
+{% if neighbor_addr | ipv4 %}
+  address-family ipv4
+    neighbor {{ neighbor_addr }} activate
+    maximum-paths 64
+  exit-address-family
+{% endif %}
 {% if neighbor_addr | ipv6 %}
   address-family ipv6
     neighbor {{ neighbor_addr }} activate