BGP Confederation plugin

Minimal skeleton for discussion

* Should BGP confederation peers be defined as a new type of neighbor? (e.g. `confed`)

Author: jbemmel

docs/module/bgp.md

@@ -50,6 +50,7 @@ Even more BGP features are implemented in the following plugins:
 * [bgp.originate](../plugins/bgp.originate.md): creates loopback interfaces instead of static routes to originate additional IPv4 or IPv6 prefixes
 * [ebgp.multihop](../plugins/ebgp.multihop.md): implements multihop EBGP sessions.
 * [bgp.domain](../plugins/bgp.domain.md): allows you to build topologies that reuse the same BGP ASN in different network parts.
+* [bgp.confederation](../plugins/bgp.confederation.md): allows you to configure BGP confederations.
 
 (bgp-platform)=
 ## Platform Support

netsim/extra/bgp.confederation/defaults.yml

@@ -0,0 +1,20 @@
+---
+bgp:
+  no_propagate:
+    confederation:
+  attributes:
+    _confed_members:
+      members:
+        type: list
+        _required: True
+        _subtype: asn
+        # Future: potential route maps, policies, settings etc. associated with the confederation
+
+    global:
+      confederation:
+        type: dict
+        _keytype: asn
+        _subtype: _confed_members
+
+devices:
+  frr.features.bgp.confederation: True

netsim/extra/bgp.confederation/frr.j2

@@ -0,0 +1,4 @@
+!
+router bgp {{ bgp.as }}
+  bgp confederation identifier {{ bgp.confederation.as }}
+  bgp confederation peers {{ bgp.confederation.peers|join(' ') }}

netsim/extra/bgp.confederation/plugin.py

@@ -0,0 +1,35 @@
+import typing
+from box import Box
+from netsim import api
+from netsim.utils import log
+
+_config_name = 'bgp.confederation'
+_requires    = [ 'bgp' ]
+
+def post_transform(topology: Box) -> None:
+  global _config_name
+  confed = topology.get('bgp.confederation')
+  if not confed:
+    return
+  
+  for n, ndata in topology.nodes.items():
+    if 'bgp' not in ndata.module:                           # Skip nodes not running BGP
+      continue
+
+    bgp_as = ndata.get('bgp.as')
+    for casn,cdata in confed.items():
+      members = cdata.get('members',[])
+      if bgp_as in members:
+        ndata.bgp.confederation['as'] = casn
+        ndata.bgp.confederation.peers = [ m for m in members if m!=bgp_as ]
+        api.node_config(ndata,_config_name)                 # Remember that we have to do extra configuration
+
+        for nb in ndata.get('bgp.neighbors',[]):            # Update remote AS used by ebgp peers
+          neighbor = topology.nodes[ nb.name ]
+          for nb2 in neighbor.get('bgp.neighbors',[]):
+            if nb2.name == n and nb2.type=='ebgp':
+              nb2['as'] = casn
+
+        # TODO: Apply ibgp type community exchange, confed is really a new type of ebgp peer
+
+        break

tests/integration/bgp.confederation/01-baseline.yml

@@ -0,0 +1,33 @@
+---
+plugin: [ bgp.confederation ]
+module: [ bgp ]
+
+bgp.confederation:
+  65000:
+    members: [ 65001, 65002 ]
+
+groups:
+  _auto_create: True
+
+  confed:
+    members: [ c1, c2 ]
+
+  ext:
+    members: [ e1 ]
+    device: frr
+    provider: clab
+
+nodes:
+  c1:
+    bgp.as: 65001
+  c2:
+    bgp.as: 65002
+    device: frr
+    provider: clab
+  e1:
+    bgp.as: 65003
+
+links:
+- c1-c2
+- c1-e1
+- c2-e1