VLAN, VRF, VXLAN, and EVPN Transformations¶
The VLAN, VRF, VXLAN, and EVPN configuration modules are tightly coupled and use shared vlans and vrfs data structures. This document describes the chain of events taking place in these modules during the netlab data transformation and how they populate the shared data structures.
The transform_after settings cause the hooks to be called in the VLAN -> VRF -> VXLAN -> EVPN order.
init¶
EVPN¶
Set default vxlan.flooding mode to evpn
pre_transform¶
VLAN¶
Module:
Create global VLANs based on group VLAN data
Collect static VLAN IDs
Validate VLAN attributes: forwarding mode, VLAN ID, link attributes, module-specific VLAN/link attributes
Auto-assign VLAN IDs to VLANs without a valid ID
Create VLAN access links in the lab topology from vlans.name.links list
Allocate IP prefixes to VLANs
Node:
Merge global VLAN data with node VLAN data
Validate VLAN attributes (see above)
Allocate IP prefixes to node-only VLANs
Link:
Validate link-level VLAN attribute: valid combinations of access/trunk/native VLANs, valid VLAN names in vlan.* link- and interface attributes
For trunk links: create VLAN member links out of a VLAN trunk
For every VLAN in the trunk, create a
vlan_member
linkProcess
vlan_member
link like it would be an access link
For access links:
Set the VLAN forwarding mode (
_vlan_mode
) for every interface attached to the link (see VLAN module documentation for precedence details)Add VLAN data to link data
For routed VLAN links, set link VLAN mode to route
For non-routed links, set link prefix based on VLAN prefix
Disable interface addresses on bridge-only VLANs or on bridge-only interfaces
VRF¶
Module:
Create global VRFs based on group VRF data
Normalize VRF IDs and collect static ID/RD settings
Auto-assign VRF ID/RD and import/export RT
Node:
Pull global VRFs that are needed by node VLANs into nodes
Normalize VRF IDs and collect static ID/RD settings
Auto-assign VRF ID/RD and import/export RT (based on some global AS)
VXLAN¶
Node:
Check/set flooding value
EVPN¶
Module:
Register static VRF evpn.transit_vni
post_node_transform¶
VXLAN¶
Module:
Create default vxlan.vlans list (all global or node VLANs) when vxlan.vlans is missing
Validate vxlan.vlans list in topology and nodes
Assign VNIs to VLANs in vxlan.vlans list
EVPN¶
Create default evpn.vrfs list when missing
Create default evpn.vlans list when missing
Assign VNIs to VRFs with evpn.transit_vni set to True or string (another VRF) value
Make sure evpn.transport is set for EVPN VLANs and (bundle) VRFs
Create VLAN- and VRF services:
Assign EVPN RD/RT to EVPN-enabled VLANs and -bundles (with RT based on some global AS, not per node AS)
Assign evpn.evi to EVPN-enabled VRFs
pre_link_transform¶
VLAN¶
Module:
Create loopback VLAN links: for every node that has a VLAN configured but does not participate in that VLAN with a physical interface, create a fake member link with a fake interface attached to it.
post_link_transform¶
VLAN¶
Module:
Copy final topology VLAN data into nodes
Create SVI interfaces
Map trunk VLAN names into VLAN IDs
Rename VLAN subinterfaces (routers and routed interfaces on L3 switches)
Remove routed native VLAN from trunk list
Check for mixed (bridged+routed) trunks
Set neighbors for SVI interfaces
Remove VLAN member links from topology links
Cleanup temporary VLAN attributes in links and nodes – remove
vlan_name
from links and interfaces,_global_merge
from VLANs and interfaces,neighbors
from node VLANs, and_vlan_mode
from interfaces. Also: copy interface_vlan_mode
into interfacevlan.mode
.Fix VLAN-wide default gateways
VRF¶
Node:
Create node VRFs based on interface vrf attributes
Merge global VRFs with node VRFs
post_transform¶
VRF¶
Node:
Check RD values for VRFs used in the node
Set af.vpnv4 and af.vpnv6 and VRF af dictionary
Check device features (inter-VRF route leaking)
Set vrf.vrfidx (used to set OSPF process ID)
Create VRF loopbacks
VXLAN¶
Module:
Build final node vxlan.vlans list
Set node VXLAN flooding domain
Build (per-node/per-VLAN) ingress replication lists
EVPN¶
Node:
Enable EVPN address family
Check VRF IRB setup against device features
Copy global EVPN lists into node data (if needed)
Trim evpn.vlans and evpn.vrfs to refer only to VLANs and VRFs present on this node
Set bgp.router_id:evpn.evi RD on EVPN-enabled VLANs and VRFs