Cisco APIC Layer 3 Networking Configuration Guide, Release 6.2(x)

WAN router and remote leaf switch configuration guidelines

Updated: April 17, 2026

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WAN routers and remote leaf switches must meet specific configuration requirements before remote leaf discovery and incorporation into Cisco Application Policy Infrastructure Controller (APIC) management. These requirements help ensure connectivity and fabric integration for remote leaf deployments.

WAN router and remote leaf switch configuration establishes communication between the fabric spine switches and remote locations.

WAN router interface configuration for Open Shortest Path First (OSPF) and Dynamic Host Configuration Protocol (DHCP) relay.
Remote leaf switch physical connectivity and Layer 3 subinterface configuration.
Tunnel endpoint (TEP) pool subnet management and Multi-Pod integration requirements.

Configuration requirements

Configure the WAN routers that connect to the fabric spine switch external interfaces and remote leaf switch ports according to the following requirements:

WAN routers :
- Enable OSPF on the interfaces. Use the same area ID, area type, and cost on the connected interfaces.
- Configure DHCP relay on the interface that leads to each APIC IP address.
- Place the WAN router interfaces that connect to the VLAN-5 interfaces on the spine switches in different virtual routing and forwarding (VRF) instances from the interfaces that connect to the regular Multi-Pod network.
Remote leaf switches :
- Connect each remote leaf switch directly to an upstream router through a fabric port.
- Use a connection of 40 Gbps or higher, or use supported 1-Gbps or 10-Gbps SFPs with an adapter.
- Configure the northbound interfaces as Layer 3 subinterfaces on VLAN-4 and assign a unique IP address to each interface.
- Enable OSPF on the interfaces, but do not configure the OSPF area as a stub area.
TEP pool :
- Ensure that the remote leaf switch TEP pool subnet does not overlap with the pod TEP subnet pool.
- Use a subnet mask of /24 or lower.
Multi-Pod integration :
- Configure an L3Out from the spine switch to the WAN router and an L3Out from the remote leaf switch to the WAN router. Use VLAN-4 on the switch interfaces.
- For a Multi-Pod deployment, configure a Multi-Pod-internal L3Out that uses VLAN-5.
- Use the same router ID for the regular Multi-Pod L3Out and the Multi-Pod-internal L3Out.
- For the Multi-Pod-internal L3Out, configure a different loopback IP address and uncheck Use Router ID as Loopback Address .

The following table lists IP address usage in a /28 remote TEP pool:

Table 1. Remote TEP pool IP address usage
IP address type	Quantity
Total usable IP addresses available in the /28 pool	16 - 2 = 14
Number of IP addresses used internally by the fabric	2
Total usable IP addresses available for nodes	14 - 2 = 12
Number of IP addresses required for 4 remote leaf switches	4 * 2 = 8
Number of IP addresses required for 2 vPC pairs	2 * 1 = 2
Total used IP addresses in the remote pool	8 + 2 = 10
Free IP addresses in the /28 remote pool	12 - 10 = 2

Note

The fabric uses two IP addresses for internal operations.

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