net/frr: Move implicit BGP address family neighbor configuration to explicit dropdown

[Monviech]

Important notices

Before you submit a pull request, we ask you kindly to acknowledge the following:

• I have read the contributing guidelines at https://github.com/opnsense/plugins/blob/master/CONTRIBUTING.md
• I opened an issue first for non-trivial changes and linked it below.
• AI tools were used to create at least part of the code submitted herewith.

If AI was used, please disclose:

• Model used: ChatGPT 5.5
• Extent of AI involvement: A bit help with the migration

---

Describe the problem

Further cleanup in BGP around the address families concept.

---

Describe the proposed solution

Now you can create an ipv4 peer that only peers ipv6 and the other way around.

It also gets rid of "Multiprotocol" toggle which implies its some sort of special BGP option but it isn't.

It's now the same as here:

plugins/net/frr/src/opnsense/mvc/app/models/OPNsense/Quagga/BGP.xml

Line 397 in 03a4c64

<family type="OptionField">

---

Related issue

Fixes: #5647

[Monviech]

Migration tested:

--- /conf/backup/config-1787058632.7462.xml	2026-08-18 15:10:32.750017000 +0200
--
+++ /conf/backup/config-1787058643.7627.xml	2026-08-18 15:10:43.768169000 +0200
@@ -716,9 +716,9 @@
<prefer>0.es.pool.ntp.org</prefer>
</ntpd>
<revision>
-    <username>root@172.16.1.150</username>
-    <description>/api/core/backup/revert_backup/config-1787057868.5365.xml made changes</description>
-    <time>1787058632.75</time>
+    <username>(root)</username>
+    <description>/usr/local/opnsense/mvc/script/run_migrations.php made changes</description>
+    <time>1787058643.76</time>
</revision>
<OPNsense>
<wireguard>
@@ -2900,7 +2900,7 @@
<redistribute/>
<defaultmetric/>
</rip>
-      <bgp version="1.1.2" persisted_at="1787057868.54" description="BGP Routing configuration">
+      <bgp version="1.1.3" persisted_at="1787058643.76" description="BGP Routing configuration">
<enabled>1</enabled>
<asnumber>41962</asnumber>
<distance/>
@@ -2918,6 +2918,7 @@
<enabled>1</enabled>
<description>REFER</description>
<address>81.90.52.153</address>
+            <family>ipv4</family>
<remote_as_mode/>
<remoteas>29003</remoteas>
<localas/>
@@ -2929,7 +2930,6 @@
<nexthopself>0</nexthopself>
<nexthopselfall>0</nexthopselfall>
<multihop>0</multihop>
-            <multiprotocol>0</multiprotocol>
<rrclient>0</rrclient>
<soft_reconfiguration_inbound>1</soft_reconfiguration_inbound>
<bfd>1</bfd>
@@ -2954,6 +2954,7 @@
<enabled>1</enabled>
<description>REFER</description>
<address>fe80::1</address>
+            <family>ipv6</family>
<remote_as_mode/>
<remoteas>29003</remoteas>
<localas/>
@@ -2965,7 +2966,6 @@
<nexthopself>0</nexthopself>
<nexthopselfall>0</nexthopselfall>
<multihop>0</multihop>
-            <multiprotocol>0</multiprotocol>
<rrclient>0</rrclient>
<soft_reconfiguration_inbound>1</soft_reconfiguration_inbound>
<bfd>1</bfd>
@@ -2990,6 +2990,7 @@
<enabled>1</enabled>
<description>REFER</description>
<address>fe80::2</address>
+            <family>ipv4,ipv6</family>
<remote_as_mode/>
<remoteas>29003</remoteas>
<localas/>
@@ -3001,7 +3002,6 @@
<nexthopself>0</nexthopself>
<nexthopselfall>0</nexthopselfall>
<multihop>1</multihop>
-            <multiprotocol>1</multiprotocol>
<rrclient>0</rrclient>
<soft_reconfiguration_inbound>1</soft_reconfiguration_inbound>
<bfd>1</bfd>