Configurable default BGP address families (implements #366)

ipspace · Sep 8, 2022 · 97890e2 · 97890e2
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diff --git a/docs/module/bgp.md b/docs/module/bgp.md
@@ -25,6 +25,7 @@ More interesting BGP topologies can be created with [custom plugins](../plugins.
 * Next-hop-self control on IBGP sessions
 * BGP community propagation
 * IPv4 and IPv6 address families
+* Configurable activation of default address families
 * Configurable link prefix advertisement
 * Additional (dummy) prefix advertisement
 * Changing local autonomous system for individual BGP sessions (*local-as*)
@@ -35,14 +36,14 @@ More interesting BGP topologies can be created with [custom plugins](../plugins.
 
 [Platforms supporting BGP configuration module](platform-routing-support) support most of the functionality mentioned above. The following features are only supported on a subset of platforms:
 
-| Operating system      | Unnumbered<br />interfaces | local AS |
-| --------------------- | :-: | :-: | 
-| Arista EOS            |  ❌  |  ✅ |
-| Cisco IOS/IOS XE      |  ❌  |  ✅ |
-| Cumulus Linux         |  ✅ |  ❌  |
-| Dell OS10             |  ❌  |  ✅ |
-| FRR 7.5.0             |  ❌  |  ❌  |
-| Nokia SR Linux        |  ✅ |  ✅ |
+| Operating system      | Unnumbered<br />interfaces | local AS | IBGP<br>local AS | Configurable<br>default AF |
+| --------------------- | :-: | :-: | :-: | :-: |
+| Arista EOS            |  ❌  |  ✅ |  ❌  |  ✅ |
+| Cisco IOS/IOS XE      |  ❌  |  ✅ |  ✅ |  ✅ |
+| Cumulus Linux         |  ✅ |  ❌  |  ❌  |  ❌  |
+| Dell OS10             |  ❌  |  ✅ |  ❌  |  ❌  |
+| FRR 7.5.0             |  ❌  |  ❌  |  ❌  |  ❌  |
+| Nokia SR Linux        |  ✅ |  ✅ |  ❌  |  ❌  |
 
 ## Global BGP Configuration Parameters
 
@@ -113,10 +114,13 @@ Finally, BGP configuration module supports these advanced node parameters that y
 
 * **bgp.rr_cluster_id** -- set static route reflector cluster ID. The default value is the lowest router ID of all route reflectors within the autonomous system.
 * **bgp.replace_global_as** (default: True) -- the default implementation of **neighbor local-as** command replaces the real autonomous system (**bgp.as**) with the *local* autonomous system. Set this parameter to *false* to disable that functionality and include both autonomous systems in the AS path[^RAS_P].
-* **bgp.sessions** -- specifies which transport sessions (IPv4 and/or IPv6) should be created for each BGP session type (IBGP, EBGP, or IBGP created through *local-as*)[^SESS_DM]. See *[bgp-sessions](https://github.com/ipspace/netlab/blob/dev/tests/topology/input/bgp-sessions.yml)* test case for an example.
+* **bgp.sessions** (node or global parameter) -- specifies which transport sessions (IPv4 and/or IPv6) should be created for each BGP session type (IBGP, EBGP, or IBGP created through *local-as*)[^SESS_DM]. See *[bgp-sessions](https://github.com/ipspace/netlab/blob/dev/tests/topology/input/bgp-sessions.yml)* test case for an example.
+* **bgp.activate** (node or global parameter) -- specifies which default address families (IPv4 AF on IPv4 session, IPv6 on IPv6 session) should be created for each BGP session type (IBGP, EBGP, or IBGP created through *local-as*)[^ACT_CFG]. See *[leaf-spine](https://github.com/ipspace/netlab/blob/dev/tests/integration/bgp/local-as/leaf-spine.yml)* local AS test case for an example.
 
 [^SESS_DM]: This parameter influences the data structures built during the data transformation phase and is thus available on all platforms supporting BGP configuration module.
 
+[^ACT_CFG]: This parameter has to be supported by the device configuration templates and is thus not available on all platforms.
+
 [^RAS_P]: This functionality might not be configurable on all platforms. For example, Arista EOS supports only the **neighbor local-as no-prepend replace-as** command.
 
 ## Link-Level Parameters

diff --git a/netsim/ansible/templates/bgp/eos.j2 b/netsim/ansible/templates/bgp/eos.j2
@@ -3,6 +3,8 @@
 router bgp {{ bgp.as }}
   bgp advertise-inactive
   bgp log-neighbor-changes
+  no bgp default ipv4-unicast
+  no bgp default ipv6-unicast
 {% if bgp.router_id|ipv4 %}
   router-id {{ bgp.router_id }}
 {% endif %}
@@ -36,7 +38,7 @@ router bgp {{ bgp.as }}
   network {{ pfx|ipaddr('0') }}
 {%     endfor %}
 !
-{%     for n in bgp.neighbors if n[af] is defined %}
+{%     for n in bgp.neighbors if n[af] is defined and n.activate[af] is defined and n.activate[af] %}
   neighbor {{ n[af] }} activate
 {%     endfor %}
 {%   endif %}

diff --git a/netsim/ansible/templates/bgp/ios.j2 b/netsim/ansible/templates/bgp/ios.j2
@@ -32,7 +32,7 @@ router bgp {{ bgp.as }}
 {{     bgpcfg.bgp_network(af,pfx) }}
 {%   endfor %}
 !
-{%   for n in bgp.neighbors if n[af] is defined %}
+{%   for n in bgp.neighbors if n[af] is defined and n.activate[af] is defined and n.activate[af] %}
 {{     bgpcfg.neighbor_af(n,n[af],bgp) }}
 {%   endfor %}
 {% endfor %}

diff --git a/netsim/modules/bgp.py b/netsim/modules/bgp.py
@@ -48,20 +48,20 @@ def check_bgp_parameters(node: Box) -> None:
 BGP_VALID_AF: typing.Final[list] = ['ipv4','ipv6']
 BGP_VALID_SESSION_TYPE: typing.Final[list] = ['ibgp','ebgp','localas_ibgp']
 
-def validate_bgp_sessions(node: Box, sessions: Box) -> bool:
+def validate_bgp_sessions(node: Box, sessions: Box, attribute: str) -> bool:
   OK = True
   for k in list(sessions.keys()):
     if not k in BGP_VALID_AF:
       common.error(
-        f'Invalid address family in bgp.sessions in node {node.name}',
+        f'Invalid address family in bgp.{attribute} in node {node.name}',
         common.IncorrectValue,
         'bgp')
       OK = False
     else:
       if data.must_be_list(
           parent=sessions,
           key=k,
-          path=f'nodes.{node.name}.bgp.sessions',
+          path=f'nodes.{node.name}.bgp.{attribute}',
           true_value=BGP_VALID_SESSION_TYPE,
           valid_values=BGP_VALID_SESSION_TYPE,
           module='bgp') is None:
@@ -229,6 +229,19 @@ def build_ebgp_sessions(node: Box, sessions: Box, topology: Box) -> None:
         else:                 # Global neighbor
           node.bgp.neighbors.append(ebgp_data)
 
+"""
+activate_bgp_default_af -- activate default AF on IPv4 and/or IPv6 transport sessions
+
+Based on transport session(s) with a BGP neighbor, local BGP AF, and BGP AF configuration
+parameters, set neighbor.activate.AF flags
+"""
+
+def activate_bgp_default_af(node: Box, activate: Box, topology: Box) -> None:
+  for ngb in node.bgp.neighbors:
+    for af in ('ipv4','ipv6'):
+      if af in ngb:
+        ngb.activate[af] = node.bgp.get(af) and af in activate and ngb.type in activate[af]
+
 """
 build_bgp_sessions: create BGP session data structure
 
@@ -250,7 +263,7 @@ def build_bgp_sessions(node: Box, topology: Box) -> None:
 
   node.bgp.neighbors = []
   bgp_sessions = node.bgp.get('sessions') or Box(BGP_DEFAULT_SESSIONS)
-  if not validate_bgp_sessions(node,bgp_sessions):
+  if not validate_bgp_sessions(node,bgp_sessions,'sessions'):
     return
 
   build_ibgp_sessions(node,bgp_sessions,topology)
@@ -264,6 +277,22 @@ def build_bgp_sessions(node: Box, topology: Box) -> None:
         node.bgp[af] = True
         break
 
+  # Activate default BGP address families
+  features = devices.get_device_features(node,topology.defaults)
+  if 'activate' in node.bgp:
+    if not features.bgp.activate_af:
+      common.error(
+        f'node {node.name} (device {node.device}) does not support configurable activation of default BGP address families',
+        common.IncorrectValue,
+        'bgp')
+      return
+
+  activate = node.bgp.get('activate') or Box(BGP_DEFAULT_SESSIONS)
+  if not validate_bgp_sessions(node,activate,'activate'):
+    return
+
+  activate_bgp_default_af(node,activate,topology)
+
 """
 bgp_set_advertise: set bgp.advertise flag on stub links
 """

diff --git a/netsim/topology-defaults.yml b/netsim/topology-defaults.yml
@@ -48,10 +48,10 @@ bgp:
   next_hop_self: true
   attributes:
     global: [ 
-      af, as, next_hop_self, rr_cluster_id, rr_list, ebgp_role, as_list, sessions,
+      af, as, next_hop_self, rr_cluster_id, rr_list, ebgp_role, as_list, sessions, activate,
       advertise_loopback, advertise_roles, community, address_families, replace_global_as ]
     node: [
-      af, as, next_hop_self, rr, rr_cluster_id, originate, advertise_loopback, sessions,
+      af, as, next_hop_self, rr, rr_cluster_id, originate, advertise_loopback, sessions, activate,
       community, router_id, address_families, local_as, replace_global_as ]
     node_copy: [ local_as, replace_global_as ]
     link: [ advertise ]
@@ -295,6 +295,7 @@ devices:
         local_as: True
         vrf_local_as: True
         local_as_ibgp: True
+        activate_af: True
       initial:
         ipv4:
           unnumbered: False
@@ -342,6 +343,7 @@ devices:
         local_as: True
         vrf_local_as: True
         local_as_ibgp: True
+        activate_af: True
       initial:
         ipv4:
           unnumbered: True
@@ -422,6 +424,7 @@ devices:
       bgp:
         local_as: True
         vrf_local_as: True
+        activate_af: True
       initial:
         system_mtu: True
         ipv4:

diff --git a/tests/integration/bgp/local-as/leaf-spine.yml b/tests/integration/bgp/local-as/leaf-spine.yml
@@ -1,15 +1,28 @@
 ---
+message: |
+  This topology creates a leaf-and-spine topology with EBGP underlay sessions
+  and IBGP sessions between loopback interfaces.
+
+  You should be able to ping between all loopback interfaces. IPv4 IBGP
+  neighbor sessions are configured but will probably be idle (no AF configured
+  on the transport session).
+
+  All IPv4 BGP routes should be EBGP routes.
 defaults.device: eos
 
 module: [ bgp ]
 
 bgp.as: 65000
+bgp.activate:
+  ipv4: [ ebgp ]
 
 nodes:
   s1:
     bgp.local_as: 65101
+    bgp.rr: True
   s2:
     bgp.local_as: 65102
+    bgp.rr: True
   l1:
     bgp.local_as: 65201
   l2:

diff --git a/tests/topology/expected/6pe.yml b/tests/topology/expected/6pe.yml
@@ -170,7 +170,10 @@ nodes:
       ipv4: true
       ipv6: true
       neighbors:
-      - as: 65000
+      - activate:
+          ipv4: true
+          ipv6: true
+        as: 65000
         ifindex: 1
         ipv4: 172.31.0.2
         ipv6: 2001:db8:2::2
@@ -221,7 +224,10 @@ nodes:
       ipv4: true
       ipv6: true
       neighbors:
-      - as: 65000
+      - activate:
+          ipv4: true
+          ipv6: true
+        as: 65000
         ifindex: 1
         ipv4: 172.31.1.2
         ipv6: 2001:db8:2:1::2
@@ -331,11 +337,17 @@ nodes:
       ipv6: true
       neighbors:
       - 6pe: true
+        activate:
+          ipv4: true
+          ipv6: true
         as: 65000
         ipv4: 10.0.0.2
         name: pe2
         type: ibgp
-      - as: 65001
+      - activate:
+          ipv4: true
+          ipv6: true
+        as: 65001
         ifindex: 1
         ipv4: 172.31.0.1
         ipv6: 2001:db8:2::1
@@ -416,11 +428,17 @@ nodes:
       ipv6: true
       neighbors:
       - 6pe: true
+        activate:
+          ipv4: true
+          ipv6: true
         as: 65000
         ipv4: 10.0.0.1
         name: pe1
         type: ibgp
-      - as: 65002
+      - activate:
+          ipv4: true
+          ipv6: true
+        as: 65002
         ifindex: 1
         ipv4: 172.31.1.1
         ipv6: 2001:db8:2:1::1

diff --git a/tests/topology/expected/addressing-ipv6-only.yml b/tests/topology/expected/addressing-ipv6-only.yml
@@ -119,15 +119,21 @@ nodes:
         - extended
       ipv6: true
       neighbors:
-      - as: 65000
+      - activate:
+          ipv6: true
+        as: 65000
         ipv6: 2001:db8:0:15::1
         name: r2
         type: ibgp
-      - as: 65000
+      - activate:
+          ipv6: true
+        as: 65000
         ipv6: 2001:db8:0:2a::1
         name: r3
         type: ibgp
-      - as: 65000
+      - activate:
+          ipv6: true
+        as: 65000
         ipv6: 2001:db8:0:1::1
         name: r4
         type: ibgp
@@ -227,15 +233,21 @@ nodes:
         - extended
       ipv6: true
       neighbors:
-      - as: 65000
+      - activate:
+          ipv6: true
+        as: 65000
         ipv6: 2001:db8:0:7::1
         name: r1
         type: ibgp
-      - as: 65000
+      - activate:
+          ipv6: true
+        as: 65000
         ipv6: 2001:db8:0:2a::1
         name: r3
         type: ibgp
-      - as: 65000
+      - activate:
+          ipv6: true
+        as: 65000
         ipv6: 2001:db8:0:1::1
         name: r4
         type: ibgp
@@ -332,15 +344,21 @@ nodes:
         - extended
       ipv6: true
       neighbors:
-      - as: 65000
+      - activate:
+          ipv6: true
+        as: 65000
         ipv6: 2001:db8:0:7::1
         name: r1
         type: ibgp
-      - as: 65000
+      - activate:
+          ipv6: true
+        as: 65000
         ipv6: 2001:db8:0:15::1
         name: r2
         type: ibgp
-      - as: 65000
+      - activate:
+          ipv6: true
+        as: 65000
         ipv6: 2001:db8:0:1::1
         name: r4
         type: ibgp
@@ -415,15 +433,21 @@ nodes:
         - extended
       ipv6: true
       neighbors:
-      - as: 65000
+      - activate:
+          ipv6: true
+        as: 65000
         ipv6: 2001:db8:0:7::1
         name: r1
         type: ibgp
-      - as: 65000
+      - activate:
+          ipv6: true
+        as: 65000
         ipv6: 2001:db8:0:15::1
         name: r2
         type: ibgp
-      - as: 65000
+      - activate:
+          ipv6: true
+        as: 65000
         ipv6: 2001:db8:0:2a::1
         name: r3
         type: ibgp

diff --git a/tests/topology/expected/bgp-anycast.yml b/tests/topology/expected/bgp-anycast.yml
@@ -57,7 +57,9 @@ nodes:
         - extended
       ipv4: true
       neighbors:
-      - as: 65000
+      - activate:
+          ipv4: true
+        as: 65000
         ipv4: 10.0.0.2
         name: l2
         type: ibgp
@@ -111,7 +113,9 @@ nodes:
         - extended
       ipv4: true
       neighbors:
-      - as: 65000
+      - activate:
+          ipv4: true
+        as: 65000
         ipv4: 10.0.0.1
         name: l1
         type: ibgp