WAN¶
Disclaimer
This how-to does not intend to be a network design nor a best practices document. It is about how to deploy a WAN network using AVD.
About PREVIEW keys in the schema
Some of the WAN functionality is still in PREVIEW. When this is the case it is indicated as such in the documentation. For these PREVIEW features, Everything is subject to change, is not supported and may not be complete.
If you have any questions, please leverage the GitHub discussions board
Overview¶
Please familiarize yourself with the Arista WAN terminology before proceeding:
- https://www.arista.com/en/solutions/enterprise-wan
- https://tech-library.arista.com/wan/ (Tech Library access requires an Arista account)
Design points¶
- When deploying CV Pathfinder, the assumption is that the deployment is using CVaaS.
- The intent is to be able to support having the different WAN participating devices in different inventories.
- Only iBGP is supported as an overlay_routing_protocol.
- On the AutoVPN Route Reflectors and Pathfinders, a listen range statement is used for BGP to allow for distributed Ansible inventories.
- VRF
default
is being configured by default on all WAN devices with awan_vni
of 1. To override this, it is necessary to configure VRFdefault
in a tenant innetwork_services
. - Path-group ID
65535
is reserved for the path-group calledLAN_HA
.
Features in PREVIEW¶
-
WAN HA is in PREVIEW
- While HA is in preview, it is required to either enable or disable HA if exactly two WAN routers are in one node group.
- For HA, the considered interfaces are only the
uplink_interfaces
in VRF default. - It is not yet supported to disable HA on a specific LAN interface on the device, nor is it supported to add HA configuration on a non-uplink interface.
- HA for AutoVPN is not supported
flow_tracking_settings
is in PREVIEW as the model will change in the next release.eos_validate_state
is being enriched to support new tests for WAN designs. These new tests are added only in the ANTA preview mode.
Known limitations¶
- Zones are not configurable for CV Pathfinder. All sites are being configured in a default zone
<region_name>-ZONE
with ID1
. Hence, ineos_designs
, thetransit
node type is always configured astransit region
. - All Pathfinders must be able to create a full mesh
- No IPv6 support
- Path-group ID is currently required under
wan_path_groups
until an algorithm is implemented to auto generate IDs. - The name of the AVT policies and AVT profiles are configurable in the input variables. The Load Balance policies are named
LB-<profile_name>
and are not configurable. - LAN support is limited to single L2 using
uplink_type: lan
and eBGP L3 usinguplink_type: p2p-vrfs
in conjunction ofunderlay_routing_protocol: ebgp
. - All the WAN routers must have a common path-group with at least one WAN route server to be able to inject the default control-plane match statement in the VRF default WAN policy.
Future work¶
- HA support out of PREVIEW
- New LAN scenarios (L2 port-channel, HA for L2
lan
using VRRP..) - HA for AutoVPN
- WAN Internet exit
import path-group
functionality- Indirect connectivity to pathfinder
- BGP peerings on WAN L3 interfaces and associated route filtering.
- Extra STUN server for a given path-group not connected to pathfinder
- Auto generation of Path-group IDs and other IDs.
- Proper OSPF-BGP redistribution in VRF default.
- Support for OSPF subinterfaces for
p2p-vrfs
. - Increase test coverage in
eos_validate_state
support for AutoVPN and CV-Pathfinder - Path selection outlier detection feature
Info
eos_cli_config_gen
schema should support all of the required keys to configure a WAN network, whether AutoVPN or Pathfinder except for the most recent features.
This means that any missing eos_designs
feature should be supported using custom_structured_configuration
functionality.
If you find any missing functionality, please open an issue on Github.
Getting started with WAN¶
Global settings¶
Tip
These global settings must be the same for every WAN device participating in the WAN network.
When using multiple inventories, the recommendation is
to include these variables from a common source, for instance leveraging the arista.avd.global_vars
Ansible plugin.
Summary¶
The following table list the eos_designs
top level keys used for WAN and how they should be set:
Key | Must be the same for all the WAN routers | Comment |
---|---|---|
wan_mode |
✅ | Two possible modes, autovpn and cv-pathfinder (default) |
wan_virtual_topologies |
✅ | to define the Policies and the VRF to policy mappings |
wan_path_groups |
✅ | to define the list of path-groups in the network |
wan_carriers |
✅ | to define the list of carriers in the network, each carrier is assigned to a path-group |
wan_ipsec_profiles |
✅ | to define the shared key for the Control Plane and Data Plane IPSec profiles. |
cv_pathfinder_regions |
✅ | to define the Region/Zone/Site hierarchy, not required for AutoVPN. |
tenants |
✅ | the default tenant key from network_services or any other key for tenant that would hold some WAN VRF informaiton |
wan_stun_dtls_disable |
✅ | disable dTLS for STUN for instance for lab. (NOT recommended in production) |
application_classification |
✅ | to define the specific traffic classification required for the WAN if any. |
wan_route_servers |
✘ | Indicate to which WAN route servers the WAN router should connect to. This key is also used to tell every WAN Route Reflectors with which other RRs it should peer with. |
ipv4_acls |
✘ | List of IPv4 access-lists to be assigned to WAN interfaces. |
Additionally, following keys must be set for the WAN route servers for the connectivity to work:
bgp_peer_groups.wan_overlay_peers.listen_range_prefixes
: To set the ranges of IP address from which to expect BGP peerings for the WAN. Include the VTEP ranges for all routers connecting to this patfinder.
WAN mode¶
AVD supports two design types for WAN:
- AutoVPN
- CV Pathfinder
By default the mode is set to cv-pathfinder
and can be changed using:
WAN node_types¶
There are two built-in node types for WAN:
wan_router
: WAN routers can be AutoVPN edges, CV Pathfinder edges or transits.wan_rr
: WAN route servers, used for the AutoVPN RRs and CV Pathfinder Pathfinder nodes.
WAN route servers¶
The AVD model for WAN has been built with the intention that it should be possible to have the different WAN routers in different inventories.
The top level wan_route_servers
allow to indicate to which AutoVPN RRs or to which Pathinders node the routers should connect to. The key can be different per region for instance.
WAN routers with this configuration will establish static peerings towards pf1 and pf2 and the common path-groups.
wan_route_servers:
- hostname: pf1
- hostname: pf2
Note
It is recommended to always have at least 2 WAN route servers for redundancy and at least one WAN route server in each path group.
When the WAN route servers are part of the same inventory, each WAN router in the inventory is able to pick up the required information to generate the configuration from the inventory device.
However, if the WAN route servers are in a different inventory, it is then necessary to add some information under the wan_route_servers
key entry. AVD will raise an error if any required information to generate the configuration is missing. Note that the configuration under wan_route_servers
takes precedence over what AVD could derive from the device if it is in the same inventory.
WAN STUN handling¶
WAN STUN connections are configured by default authenticated and secured with DTLS by default. A security profile is configured with an hardcoded root certificate and matching a certifcate <profile_name>.crt
and key <profile_name>.key
:
management security
ssl profile STUN-DTLS
tls versions 1.2
trust certificate aristaDeviceCertProvisionerDefaultRootCA.crt
certificate STUN-DTLS.crt key STUN-DTLS.key
These values can be overwritten using custom_structured_configuration
.
This configuration requires certificates to be distributed on the WAN devices to be able to authenticate themselves:
- For CV Pathinder deployments, CloudVision will automatically deploy certificates on the devices.
- For AutoVPN, the certficiates must be generated and deployed to the devices for the STUN connections to work.
Disabling STUN
It is possible to disable STUN using AVD but this implies that the STUN service is exposed with no authentication.
# Use wan_stun_dtls_disable: true to disable STUN on all WAN devices
wan_stun_dtls_disable: true
# Use wan_stun_dtls_profile_name to overwrite the default profile name STUN-DTLS
wan_stun_dtls_profile_name: profileA
CV Pathfinder hierarchy¶
When deploying CV Pathfinder, it is required to define a WAN hierarchy grouping WAN sites in WAN regions using the top
level key cv_pathfinder_regions
. Furthermore each WAN router must be assigned to a region and site in the node settings.
An example hierarchy looks like:
cv_pathfinder_regions:
- name: Region_1
id: 1
description: AVD Region 1
sites:
- name: Site11
id: 11
location: Somewhere
- name: Site12
id: 12
location: Somewhere else
- name: Region_2
id: 2
description: AVD Region 2
sites:
- name: Site11
id: 11
- name: Site21
id: 21
Note
Site IDs and names must be unique per region.
And then for each wan_router
:
For Pathfinders (wan_rr
), it is possible to set the cv_pathfinder_region
key. It is not rendered in configuration but leveraged in CloudVision for the visualization.
WAN carriers and path-groups¶
Path-groups are used to define overlays over the various network transports a WAN can use.
In AVD, the list of desired path-groups must be defined the same across all WAN participating routers using the following top level key.
wan_path_groups:
- name: MPLS
ipsec:
static_peers: false
dynamic_peers: false
dps_keepalive:
interval: 300
id: 100
- name: INET
id: 101
- name: LTE
excluded_from_default_policy: true
id: 102
- name: Equinix
default_preference: alternate
id: 103
- name: Satellite
id: 104
Note
The IDs are required and it is possible to turn on and off IPSec at the path-group level for dynamic or static peers.
To allow for a better visualization in CVaaS, AVD implements on level of indirection to be able to specify the carrier for the last mile provider. In addition some settings have been made available at the WAN carrier level like trusted
.
Each carrier is associated to a path-group and multiple carriers can be assigned to the same path-group (e.g. all the Internet providers can be differentiated at the carrier level but bundled together at the path-group level).
The list of carriers must also be the same across all WAN routers:
wan_carriers:
- name: IPS-1
path_group: INET
- name: ISP-2
path_group: INET
- name: MPLS-SP1
path_group: MPLS
trusted: true
- name: MPLS-SP2
path_group: MPLS
trusted: true
- name: LTE-5G-SP
path_group: LTE
- name: Satellite-SP
path_group: Satellite
Flow tracking¶
For scalabilty reasons, flow-tracking is enabled only on Dps1
interface by default.
It can be added on WAN and LAN interfaces using custom_structured_configuration
.
WAN interfaces¶
A WAN interface in AVD is defined under the node settings under the l3_interfaces
list. To be considered as a WAN interface by AVD, the l3_interface
must have the wan_carrier
key defined (which will allow to detect the path-group thanks to the carrier to path-group mapping). The wan_circuit_id
is optional and used on CVaaS to provide more information in the visualization as well as in the AVD generated interface description. Finally the key connected_to_pathfinder
allows to disable the static peering configuration on a given path-group.
Danger
The WAN interfaces may be connected directly to the Internet, it is the user’s responsibility to craft the ACLs required to ensure only the expected traffic is accepted and sent.
wan_router:
defaults:
loopback_ipv4_pool: 192.168.42.0/24
vtep_loopback_ipv4_pool: 192.168.142.0/24
uplink_ipv4_pool: 172.17.0.0/16
bgp_as: 65000
cv_pathfinder_region: Region_1
cv_pathfinder_site: Site11
nodes:
- name: cv-pathfinder-edge
id: 1
uplink_switch_interfaces: [Ethernet1]
l3_interfaces:
# This is a WAN interface because `wan_carrier` is defined
- name: Ethernet1
peer: peer3
peer_interface: Ethernet42
wan_carrier: ISP-1
wan_circuit_id: 666
ipv4_acl_in: TEST-IPV4-ACL-WITH-IP-FIELDS-IN
ipv4_acl_out: TEST-IPV4-ACL-WITH-IP-FIELDS-OUT
dhcp_accept_default_route: true
ip_address: dhcp
dhcp_ip: 7.7.7.7
- name: Ethernet2
wan_carrier: MPLS-1
wan_circuit_id: 10555
ip_address: 172.15.5.5/31
peer_ip: 172.16.5.4
static_routes:
- prefix: 172.16.0.0/16
connected_to_pathfinder: False
# This is NOT a WAN interface
- name: Ethernet3
ip_address: 172.20.20.20/31
WAN policies¶
The policies definition works as follow:
- The policies are defined under
wan_virtual_topologies.policies
. For AutoVPN mode, the policies are configured underrouter path-selection
, for CV Pathfinder, they are configured underrouter adaptive-virtual-topology
. - A policy is composed of a list of
application_virtual_topologies
and onedefault_virtual_topology
. - The
application_virtual_topologies
entries and thedefault_virtual_topology
key are used to create the policy match statement, the AVT profile (whenwan_mode
is CV Pathfinder) and the load balancing policy. - The
default_virtual_topology
is used as the default match in the policy. To prevent configuring it, thedrop_unmatched
boolean must be set totrue
otherwise, at least onepath-group
must be configured or AVD will raise an error. - Policies are assigned to VRFs using the list
wan_virtual_topologies.vrfs
. A policy can be reused in multiple VRFs. - If no policy is assigned for the
default
VRF policy, AVD auto generates one with onedefault_virtual_topology
entry configured to use all available local path-groups. - For the policy defined for VRF
default
(or the auto-generared one), an extra match statement is injected in the policy to match the traffic towards the Pathfinders or AutoVPN RRs, the name of the application-profile is hardcoded asAPP-PROFILE-CONTROL-PLANE
. A special policy is created by appending-WITH-CP
at the end of the targetted policy name. - For the policy defined for VRF
default
(or the auto-generated one), an extra match statement is always injected in the policy to match the traffic towards the Pathfinders or AutoVPN RRs. The name of the injected application-profile is hardcoded asAPP-PROFILE-CONTROL-PLANE
. A special policy is created by appending-WITH-CP
at the end of the targeted policy name.
wan_virtual_topologies:
vrfs:
- name: PROD
policy: PROD-AVT-POLICY
wan_vni: 42
- name: default
wan_vni: 1
policies:
- name: PROD-AVT-POLICY
default_virtual_topology:
path_groups:
- names: [INET]
preference: preferred
- names: [MPLS]
preference: alternate
application_virtual_topologies:
- application_profile: VOICE
lowest_hop_count: true
path_groups:
- names: [MPLS]
preference: preferred
- names: [INET]
preference: alternate
constraints:
delay: 120
jitter: 20
loss_rate: 0.3
id: 2
- application_profile: VIDEO
path_groups:
- names: [MPLS, LTE]
preference: preferred
- names: [INET]
preference: alternate
constraints:
loss_rate: 42.0
id: 4
# This will not be rendered on devices without MPLS
- application_profile: MPLS-ONLY
path_groups:
- names: [MPLS]
preference: preferred
id: 5
LAN Designs¶
VRF default routing
An important design point to keep in mind is that the current CV Pathfinder and AutoVPN solutions require the Dps1
interface to be in VRF default.
This implies that all the WAN interfaces will also be in VRF default
and there may also be LAN interfaces in VRF default
.
The following LAN scenarios are supported:
- Single Router L3 EBGP LAN
- Single Router L2 LAN
The following LAN scenarios are in PREVIEW:
- Dual Router L3 EBGP LAN with HA
EBGP LAN¶
- the Site of Origin (SoO) extended community is configured as
: note: site id is unique per zone (only a default zone supported today). - the routes redistributed into BGP via the route-map
RM-CONN-2-BGP
are tagged with the SoO. - the Underlay peer group (towards the LAN) is configured with two route-maps reused from existing designed but configured differently
- one outbound route-map
RM-BGP-UNDERLAY-PEERS-OUT
:- advertised the local routes tagged with the SoO extended community.
- advertised the routes received from iBGP (WAN) towards the LAN also marked with the SoO community.
- one inbound route-map
RM-BGP-UNDERLAY-PEERS-IN
:- deny routes received from LAN that already contain the WAN AS in the path.
- accept routes coming from the LAN and set the SoO extended community on them.
- one outbound route-map
- For VRF default, there is a requirement to explicitly redistribute the routes for EVPN. The
RM-EVPN-EXPORT-VRF-DEFAULT
is configured to export the routes tagged with the SoO.
HA (PREVIEW)¶
PREVIEW: Changes ahead
This configuration currently in PREVIEW will change in future version of AVD.
for eBGP LAN routing protocol the following is done to enable HA:
- the uplink interfaces are used as HA interfaces.
- the subnets of the HA interfaces are redistributed to BGP via the
RM-CONN-2-BGP
route-map BGP underlay peer group is configured withallowas-in 1
to be able to learn the HA peer uplink interface subnet over the LAN as well as learning WAN routes from other sites (as backup in case all WAN links are lost). - the Underlay peer group is configured with two route-maps
- one inbound route-map
RM-UNDERLAY-PEERS-IN
- Match HA peer’s uplink subnets (not marked) to be able to form HA tunnel (not exported to EVPN).
- Match HA peer’s originated prefixes, set longer AS path and mark with SoO to export to EVPN. These will be used as backup from other sites to destinations on HA Peer Router in case all WAN connections on Peer are down.
- Match all WAN routes using AS path and set no-advertise community. This will be used as backup routes to the WAN in case this router looses all WAN connections.
- Match anything else (LAN prefixes) and mark with the SoO
<bgp_as>:<wan_site_id>
to export to EVPN.
- one outbound route-map
RM-UNDERLAY-PEERS-OUT
- allowing local routes marked with SoO (routes/interfaces defined via tenants + router-id)
- allowing subnets of uplink interfaces.
- allow all routes learned from iBGP (WAN)
- Implicitly denying other routes which could be learned from BGP towards a WAN provider or redistributed without marking with SoO.
- one inbound route-map
OSPF LAN (NOT SUPPORTED)¶
NOT SUPPORTED
This configuration is not supported and has not been thoroughly tested. Use at your own risk.
- Configure
underlay_routing_protocol
to OSPF for both the WAN router and the uplink router.
HA¶
The HA tunnel will come up properly today but route redistribution will be missing so it is not usable.
- the HA interface(s) is(are) the uplink interface(s) which are automatically included in OSPF.
L2 LAN¶
Warning
In the current implementation, OSPF on LAN is not supported as there is no redistribution of route from OSPF to BGP and vice-versa implemented.
HA (NOT IMPLEMENTED)¶
NOT IMPLEMENTED
Not Implemented - will be using VRRP
CloudVision Tags¶
arista.avd.eos_designs
will generate CloudVision Tags that assist CloudVision with visualizing the WAN.
The tags will only be generated when wan_mode
is set to cv-pathfinder
.
Device Tags¶
Tag Name | Source of information |
---|---|
Region |
cv_pathfinder_region |
Zone |
<region_name>-ZONE for wan_router |
Site |
cv_pathfinder_site for wan_router |
PathfinderSet |
name of node_group or default PATHFINDERS for wan_rr |
Role |
pathfinder , edge , transit region or transit zone |
Interface Tags¶
Hint Tag Name | Source of information |
---|---|
Type |
lan or wan |
Carrier |
wan_carrier if this is a WAN interface |
Circuit |
wan_circuit_id if this is a WAN interface |
Using separate Ansible inventories¶
As described in the design principles, the goal is to be able to distribute the WAN routers in separate Ansible inventories.
When leveraging multiple inventories, the arista.avd collection provide capabilites to create global variables. The following example will be leveraging this capability to share required WAN variables accross multiple inventories.
This example contains contains two sites, SITE1 and SITE2 and a dedicate inventory for pathfinder nodes. This would still relevant for configuring AutoVPN in seperate ansible inventories.
Inventory layout:
- The PATHFINDERS inventory contains the
wan_rr
node types. - SITE1 and SITE2 inventories contains the following node types:
wan_router
,spine
,l3leaf
.
├── global_vars
│ ├── common.yml
│ └── cv_pathfinder.yml
├── PATHFINDERS
│ ├── group_vars
│ │ └── Pathfinders.yml
│ └── inventory.yml
├── SITE1
│ ├── group_vars
│ │ ├── LEAFS.yml
│ │ ├── SITE1.yml
│ │ ├── SPINES.yml
│ │ └── WAN_ROUTERS.yml
│ ├── host_vars
│ │ └── inventory_hostname.yml
│ └── inventory.yml
├── SITE2
│ ├── group_vars
│ │ ├── LEAFS.yml
│ │ ├── SITE2.yml
│ │ ├── SPINES.yml
│ │ └── WAN_ROUTERS.yml
│ ├── host_vars
│ │ └── inventory_hostname.yml
│ └── inventory.yml
wan_mode: cv-pathfinder
# When Pathfinders are in a seperate inventory in addition to the hostname you also need to capture the `vtep_ip` and `path_groups`.
wan_route_servers:
- hostname: pf1
vtep_ip: 10.255.0.1
path_groups:
- name: mpls
interfaces:
- name: Ethernet1
public_ip: 172.18.1.2/24
- name: internet
interfaces:
- name: Ethernet2
public_ip: 100.64.1.2/24
- hostname: pf2
vtep_ip: 10.255.0.2
path_groups:
- name: mpls
interfaces:
- name: Ethernet1
public_ip: 172.18.2.2/24
- name: internet
interfaces:
- name: Ethernet2
public_ip: 100.64.2.2/24
# Suggested variables to share in your global variables accross inventories.
cv_pathfinder_regions:
- name: Global
id: 1
sites:
- name: SITE1
id: 101
- name: SITE2
id: 102
bgp_peer_groups:
wan_overlay_peers:
password: "htm4AZe9mIQOO1uiMuGgYQ=="
listen_range_prefixes:
- 10.0.0.0/8
wan_ipsec_profiles:
control_plane:
shared_key: 0110100A480E0A0E231D1E
data_plane:
shared_key: 0110100A480E0A0E231D1E
wan_path_groups:
- name: mpls
id: 101
- name: internet
id: 102
wan_carriers:
- name: isp-1
path_group: internet
- name: mpls-sp-1
path_group: mpls
wan_virtual_topologies:
vrfs:
- name: default
policy: DEFAULT-AVT-POLICY
wan_vni: 1
- name: data
policy: DATA-AVT-POLICY
wan_vni: 20
- name: guest
policy: GUEST-AVT-POLICY
wan_vni: 10
policies:
- name: DEFAULT-AVT-POLICY
default_virtual_topology:
path_groups:
- names: [internet]
preference: preferred
- name: GUEST-AVT-POLICY
default_virtual_topology:
path_groups:
- names: [internet]
preference: preferred
- name: DATA-AVT-POLICY
default_virtual_topology:
path_groups:
- names: [mpls]
preference: preferred
- names: [internet]
preference: alternate