Unify loopback and virtual interface processing

* Change 'create_loopback_interface' into a framework that supports multiple virtual interface types * Assign virtual interface ifindex based on existing interfaces of the same virtual interface type * Create interface name from device template or use 'ifname' if there is no device interface-specific name template * Adjust ifindex based on virtual interface type to prevent clashes with physical or other virtual interfaces * Use common framework when creating VRF loopbacks
ipspace · Apr 16, 2023 · 0b20f69 · 0b20f69
1 parent 60ebd84
commit 0b20f69
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Showing 10 changed files with 112 additions and 96 deletions.
diff --git a/netsim/augment/links.py b/netsim/augment/links.py
@@ -16,6 +16,8 @@
 from .. import addressing
 from . import devices
 
+VIRTUAL_INTERFACE_TYPES: typing.Final[typing.List[str]] = [ 'loopback', 'tunnel' ]
+
 def adjust_interface_list(iflist: list, link: Box, nodes: Box) -> list:
   link_intf = []
   intf_cnt  = 0
@@ -202,7 +204,10 @@ def create_regular_interface(node: Box, ifdata: Box, defaults: Box) -> None:
 
   # When computing default ifindex, consider only non-loopback interfaces
   if not ifindex:
-   ifindex = len([intf for intf in node.interfaces if intf.get('type',None) != 'loopback']) + ifindex_offset
+   ifindex = len([
+               intf for intf in node.interfaces
+                 if not intf.get('type',None) in VIRTUAL_INTERFACE_TYPES
+                 ]) + ifindex_offset
 
   ifname_format = devices.get_device_attribute(node,'interface_name',defaults)
 
@@ -219,31 +224,42 @@ def create_regular_interface(node: Box, ifdata: Box, defaults: Box) -> None:
     provider = devices.get_provider(node,defaults)
     ifdata[provider] = pdata
 
-def create_loopback_interface(node: Box, ifdata: Box, defaults: Box) -> None:
-  ifindex_offset = devices.get_device_attribute(node,'loopback_offset',defaults) or 0
-  ifdata.ifindex = ifindex_offset + ifdata.linkindex
+def create_virtual_interface(node: Box, ifdata: Box, defaults: Box) -> None:
+  devtype = ifdata.get('type','loopback')         # Get virtual interface type, default to loopback interface
+  ifindex_offset = (
+    devices.get_device_attribute(node,f'{devtype}_offset',defaults) or
+    1 if devtype == 'loopback' else 0)            # Loopback interfaces have to start with 1 to prevent overlap with built-in loopback
+
   ifdata.virtual_interface = True
-  ifname_format  = devices.get_device_attribute(node,'loopback_interface_name',defaults)
+  if not 'ifindex' in ifdata:
+    ifdata.ifindex = len([intf for intf in node.interfaces if intf.get('type',None) == devtype]) + ifindex_offset
+  ifname_format  = devices.get_device_attribute(node,f'{devtype}_interface_name',defaults)
 
   if not ifname_format:
-    common.error(
-      f'Device {node.device}/node {node.name} does not support loopback links',
-      common.IncorrectValue,
-      'links')
-    return
+    if devtype == 'loopback':
+      common.error(
+        f'Device {node.device}/node {node.name} does not support loopback links',
+        common.IncorrectValue,
+        'links')
+      return
+    else:
+      common.error(
+        f'Need explicit interface name (ifname) for {devtype} interface on node {node.name} ({node.device})',
+        common.IncorrectValue,
+        'links')
+      return
 
   if not 'ifname' in ifdata:
     ifdata.ifname = utils.strings.eval_format(ifname_format,ifdata)
 
-  # If the device uses 'loopback_offset' then we're assuming it's large enough to prevent overlap with physical interfaces
-  # Otherwise, create fake ifindex for loopback interfaces to prevent that overlap
+  # Adjust ifindex to prevent overlap between device types
   #
-  if not ifindex_offset:
-    ifdata.ifindex = 10000 + ifdata.ifindex
+  ifindex_offset = (VIRTUAL_INTERFACE_TYPES.index(devtype)+1) * 10000
+  ifdata.ifindex += ifindex_offset
 
 def add_node_interface(node: Box, ifdata: Box, defaults: Box) -> Box:
-  if ifdata.get('type') == 'loopback':
-    create_loopback_interface(node,ifdata,defaults)
+  if ifdata.get('type',None) in VIRTUAL_INTERFACE_TYPES:
+    create_virtual_interface(node,ifdata,defaults)
   else:
     create_regular_interface(node,ifdata,defaults)
 

diff --git a/netsim/modules/vrf.py b/netsim/modules/vrf.py
@@ -253,8 +253,7 @@ def validate_vrf_route_leaking(node : Box) -> None:
             'vrf')
 
 def vrf_loopbacks(node : Box, topology: Box) -> None:
-  loopback_name = devices.get_device_attribute(node,'loopback_interface_name',topology.defaults) or \
-                  devices.get_device_attribute(node,'features.vrf.loopback_interface_name',topology.defaults)
+  loopback_name = devices.get_device_attribute(node,'loopback_interface_name',topology.defaults)
 
   if not loopback_name:                                                        # pragma: no cover -- hope we got device settings right ;)
     common.print_verbose(f'Device {node.device} used by {node.name} does not support VRF loopback interfaces - skipping assignment.')
@@ -265,19 +264,20 @@ def vrf_loopbacks(node : Box, topology: Box) -> None:
                         node = node,
                         topology = topology)
   for vrfname,v in node.vrfs.items():
-    vrf_loopback = v.get('loopback',None) or node_vrf_loopback              # Do we have VRF loopbacks enabled in the node or in the VRF?
-    if not vrf_loopback:                                                    # ... nope, move on
+    vrf_loopback = v.get('loopback',None) or node_vrf_loopback        # Do we have VRF loopbacks enabled in the node or in the VRF?
+    if not vrf_loopback:                                              # ... nope, move on
       continue
 
-    ifdata = data.get_box({
-      'virtual_interface': True,
+    # Note: set interface ifindex to v.vrfidx if you want to have VRF-numbered loopbacks
+    #
+    ifdata = data.get_box({                                           # Create interface data structure
       'type': "loopback",
       'name': f'VRF Loopback {vrfname}',
-      'ifindex': node.interfaces[-1].ifindex + 1,
-      'ifname': loopback_name.format(vrfidx=v.vrfidx,ifindex=v.vrfidx),     # Use VRF-specific and generic loopback index
       'neighbors': [],
       'vrf': vrfname,})
 
+    links.create_virtual_interface(node,ifdata,topology.defaults)     # Use common function to create loopback interface
+
     if isinstance(vrf_loopback,bool):
       vrfaddr = addressing.get(topology.pools, ['vrf_loopback'])
     else:

diff --git a/tests/topology/expected/bgp.yml b/tests/topology/expected/bgp.yml
@@ -148,8 +148,8 @@ links:
     ipv4: 172.16.1.0/24
   type: stub
 - interfaces:
-  - ifindex: 10009
-    ifname: Loopback9
+  - ifindex: 10001
+    ifname: Loopback1
     ipv4: 172.16.2.6/24
     node: e2
   linkindex: 9
@@ -302,8 +302,8 @@ nodes:
       type: stub
     - bgp:
         advertise: true
-      ifindex: 10009
-      ifname: Loopback9
+      ifindex: 10001
+      ifname: Loopback1
       ipv4: 172.16.2.6/24
       linkindex: 9
       name: e2 -> stub

diff --git a/tests/topology/expected/group-data-vrf.yml b/tests/topology/expected/group-data-vrf.yml
@@ -58,16 +58,16 @@ nodes:
         vrf: red
       type: p2p
       vrf: red
-    - ifindex: 2
-      ifname: Loopback101
+    - ifindex: 10001
+      ifname: Loopback1
       ipv4: 10.2.0.1/32
       name: VRF Loopback red
       neighbors: []
       type: loopback
       virtual_interface: true
       vrf: red
-    - ifindex: 3
-      ifname: Loopback100
+    - ifindex: 10002
+      ifname: Loopback2
       ipv4: 10.2.0.2/32
       name: VRF Loopback blue
       neighbors: []
@@ -134,8 +134,8 @@ nodes:
               passive: false
             type: p2p
             vrf: red
-          - ifindex: 2
-            ifname: Loopback101
+          - ifindex: 10001
+            ifname: Loopback1
             ipv4: 10.2.0.1/32
             name: VRF Loopback red
             neighbors: []
@@ -168,16 +168,16 @@ nodes:
         vrf: red
       type: p2p
       vrf: red
-    - ifindex: 2
-      ifname: Loopback101
+    - ifindex: 10001
+      ifname: Loopback1
       ipv4: 10.2.0.3/32
       name: VRF Loopback red
       neighbors: []
       type: loopback
       virtual_interface: true
       vrf: red
-    - ifindex: 3
-      ifname: Loopback100
+    - ifindex: 10002
+      ifname: Loopback2
       ipv4: 10.2.0.4/32
       name: VRF Loopback blue
       neighbors: []
@@ -244,8 +244,8 @@ nodes:
               passive: false
             type: p2p
             vrf: red
-          - ifindex: 2
-            ifname: Loopback101
+          - ifindex: 10001
+            ifname: Loopback1
             ipv4: 10.2.0.3/32
             name: VRF Loopback red
             neighbors: []

diff --git a/tests/topology/expected/igp-af.yml b/tests/topology/expected/igp-af.yml
@@ -76,8 +76,8 @@ links:
   role: stub
   type: stub
 - interfaces:
-  - ifindex: 10006
-    ifname: Loopback6
+  - ifindex: 10001
+    ifname: Loopback1
     ipv4: 10.2.0.1/32
     ipv6: 2001:db8:cafe::5/64
     node: r5
@@ -394,8 +394,8 @@ nodes:
         passive: true
       role: stub
       type: stub
-    - ifindex: 10006
-      ifname: Loopback6
+    - ifindex: 10001
+      ifname: Loopback1
       ipv4: 10.2.0.1/32
       ipv6: 2001:db8:cafe::5/64
       isis:

diff --git a/tests/topology/expected/link-loopback.yml b/tests/topology/expected/link-loopback.yml
@@ -14,8 +14,8 @@ links:
     ipv4: 172.16.0.0/24
   type: lan
 - interfaces:
-  - ifindex: 10002
-    ifname: Loopback2
+  - ifindex: 10001
+    ifname: Loopback1
     ipv4: 172.16.1.1/24
     node: r1
   linkindex: 2
@@ -35,8 +35,8 @@ links:
     ipv4: 172.16.2.0/24
   type: stub
 - interfaces:
-  - ifindex: 10004
-    ifname: Loopback4
+  - ifindex: 10001
+    ifname: Loopback1
     ipv4: 10.1.0.1/32
     node: r2
   linkindex: 4
@@ -45,8 +45,8 @@ links:
     ipv4: 172.16.3.0/24
   type: loopback
 - interfaces:
-  - ifindex: 10005
-    ifname: Loopback5
+  - ifindex: 10002
+    ifname: Loopback2
     ipv4: 10.1.0.2/32
     node: r1
   linkindex: 5
@@ -55,8 +55,8 @@ links:
     ipv4: 10.1.0.2/32
   type: loopback
 - interfaces:
-  - ifindex: 10006
-    ifname: Loopback6
+  - ifindex: 10003
+    ifname: Loopback3
     ipv4: 10.2.0.1/32
     node: r1
   linkindex: 6
@@ -96,24 +96,24 @@ nodes:
     device: eos
     id: 1
     interfaces:
-    - ifindex: 10002
-      ifname: Loopback2
+    - ifindex: 10001
+      ifname: Loopback1
       ipv4: 172.16.1.1/24
       linkindex: 2
       name: r1 -> stub
       neighbors: []
       type: loopback
       virtual_interface: true
-    - ifindex: 10005
-      ifname: Loopback5
+    - ifindex: 10002
+      ifname: Loopback2
       ipv4: 10.1.0.2/32
       linkindex: 5
       name: r1 -> stub
       neighbors: []
       type: loopback
       virtual_interface: true
-    - ifindex: 10006
-      ifname: Loopback6
+    - ifindex: 10003
+      ifname: Loopback3
       ipv4: 10.2.0.1/32
       linkindex: 6
       name: r1 -> stub
@@ -144,8 +144,8 @@ nodes:
       name: r2 -> stub
       neighbors: []
       type: stub
-    - ifindex: 10004
-      ifname: Loopback4
+    - ifindex: 10001
+      ifname: Loopback1
       ipv4: 10.1.0.1/32
       linkindex: 4
       name: r2 -> stub

diff --git a/tests/topology/expected/vrf-igp.yml b/tests/topology/expected/vrf-igp.yml
@@ -192,8 +192,8 @@ nodes:
         vrf: blue
       type: p2p
       vrf: blue
-    - ifindex: 4
-      ifname: Loopback101
+    - ifindex: 10001
+      ifname: Loopback1
       ipv4: 10.2.0.1/32
       name: VRF Loopback blue
       neighbors: []
@@ -255,8 +255,8 @@ nodes:
               passive: false
             type: p2p
             vrf: blue
-          - ifindex: 4
-            ifname: Loopback101
+          - ifindex: 10001
+            ifname: Loopback1
             ipv4: 10.2.0.1/32
             name: VRF Loopback blue
             neighbors: []
@@ -360,8 +360,8 @@ nodes:
         node: r3
       type: p2p
       vrf: blue
-    - ifindex: 4
-      ifname: Loopback100
+    - ifindex: 10001
+      ifname: Loopback1
       ipv4: 10.2.0.2/32
       name: VRF Loopback blue
       neighbors: []
@@ -441,8 +441,8 @@ nodes:
               passive: false
             type: p2p
             vrf: blue
-          - ifindex: 4
-            ifname: Loopback100
+          - ifindex: 10001
+            ifname: Loopback1
             ipv4: 10.2.0.2/32
             name: VRF Loopback blue
             neighbors: []