SD-WAN Router and Template Configuration
SD-WAN Router and Template Configuration
This domain tests how WAN Edges get their configuration: feature templates, device templates, CLI add-on templates, variables, and the onboarding steps that take a factory device to a working TLOC.
Template hierarchy
- Feature template - one reusable configuration block of a type: System, VPN, Ethernet interface, BGP, OSPF, static route, ACL, QoS, SNMP. Its scope is either global (all devices) or device specific (one model).
- Device template - one per device model; collects the feature templates plus a CLI add-on template and holds the per-device variable values. Attaching it triggers the configuration push.
- CLI add-on template - free-form IOS-XE or vEdge CLI for features without a feature template. It supports variables but bypasses template validation, so a typo pushes a broken configuration.
- Newer releases add configuration groups, a hierarchical alternative for scale; templates remain the exam baseline.
Variables
Each feature-template field can be Global (fixed), Default (overridable) or Variable (must be supplied). Variables let one template serve many sites; the device template supplies the values. Unresolved variables block attachment.
Bootstrap and onboarding
Controllers must have the edge's serial number in vManage's allowed list (WAN Edge List) or onboard it through PnP. The bootstrap itself needs only host name, system-ip, site-id, organization name, vBond address and a certificate. Once control connections are up, attach the device template: interfaces, tunnels and TLOCs get configured, and templates can be re-pushed after edits.
Worked example
A cEdge with two transports: Gi1 is MPLS with a static /30, Gi2 is business internet with DHCP. Build a System feature template with variables for system-ip and site-id; two VPN 0 interface feature templates (Gi1 static with color mpls, Gi2 DHCP with color biz-internet); a VPN 10 service VPN with a loopback and a default route toward the transports. The device template binds them, you enter the variable values and attach. Verify with show sdwan control connections (three connections up) and show sdwan omp tlocs (two TLOCs).
Traps
- Editing a global feature template silently changes every device attached to it.
- Forgetting the VPN 0 transport interface means no TLOC and no tunnels.
- Attaching a device template to the wrong model fails immediately.
- Out-of-band CLI changes are overwritten on the next template push.