Building a Future-Ready Hybrid WAN: How VRF Lite, PBR, and SD-WAN Power Global Enterprise Networks

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Preface:

 

From a network architect’s point of view, VRF Lite, PBR and SD-WAN gives you a super flexible, secure and performance optimized WAN architecture. VRF Lite gives you logical segmentation on shared infrastructure so you can keep sensitive departments like Finance isolated without having to deploy separate physical links. PBR gives you precise rule-based traffic steering at specific sites - ideal for enforcing static business policies like forcing ERP traffic onto MPLS or keeping guest Wi-Fi on broadband even in non-SD-WAN locations. SD-WAN is the overarching intelligent WAN fabric that gives you centralized control, application aware routing and dynamic path selection to optimize performance for real-time and cloud-based applications. Together they give you granular control, robust security segmentation and agile traffic optimization across a hybrid WAN that aligns to your compliance needs and evolving business performance requirements.



Scenario: ShopWorld Inc., a global retail company with HQ in New York (Data Center and Internet Gateway) and branches in Chicago (MPLS & Broadband), London (MPLS & LTE backup), and Mumbai (Broadband & LTE only) has a hybrid WAN to meet all the business needs. The network design ensures that all ERP application traffic is routed over MPLS for low latency and SLAs, guest Wi-Fi is isolated from corporate resources and forced to use broadband Internet, VoIP traffic is dynamically steered over the path with the lowest latency—MPLS or Internet—based on real-time link performance. Cloud applications like Office 365 and Salesforce use local Internet breakout to minimize latency and improve user experience. Finance department’s network is completely logically separated from all other corporate traffic as per compliance policies to ensure data privacy and regulatory adherence across all sites.



Step-1 Need to create VRF Lite Configuration (HQ & Branch 2)

- We create VRF-Corp, VRF-Finance, and VRF-Guest for segmentation.


# Define VRFs

R1(config) # ip vrf VRF-Corp

R1(config)  # rd 100:1

R1(config)  # route-target export 100:1

R1(config) #  route-target import 100:1

 

R2 (config) # ip vrf VRF-Finance

R2 (config) # rd 100:2

R2 (config) # route-target export 100:2

R2 (config) #  route-target import 100:2

 

R3 (config) # ip vrf VRF-Guest

R3 (config) #  rd 100:3

R3 (config) #  route-target export 100:3

R3 (config) #  route-target import 100:3

 

! Assign VRFs to interfaces

R1(config) # interface GigabitEthernet0/0

R1 (config) #  description Corp LAN

R1 (config) #  ip vrf forwarding VRF-Corp

R1 (config) #  ip address 10.10.0.1 255.255.255.0

 

R2 (config) # interface GigabitEthernet0/1

R2 (config) # description Finance LAN

R2 (config) #  ip vrf forwarding VRF-Finance

R2 (config) #  ip address 10.20.0.1 255.255.255.0

 

R3 (config) # interface GigabitEthernet0/2

R3 (config) # description Guest LAN

R3 (config) #  ip vrf forwarding VRF-Guest

 R3 (config) # ip address 10.30.0.1 255.255.255.0


Step-2 Policy-Based Routing (PBR) Configuration (Branch 1 & Branch 2)

We ensure ERP VLAN (10.10.50.0/24) always goes to MPLS, and Guest VLAN (10.30.0.0/24) always uses Broadband.


# Define access lists for traffic match

R4 (config) # ip access-list extended ERP_TRAFFIC

R4 (config) #  permit ip 10.10.50.0 0.0.0.255 any

R4 (config) # ip access-list extended GUEST_TRAFFIC

R4 (config) #  permit ip 10.30.0.0 0.0.0.255 any


! Route-maps for PBR

R4 (config) # route-map ERP_TO_MPLS permit 10

R4 (config) #  match ip address ERP_TRAFFIC

 R4 (config) # set ip next-hop 192.168.1.1  ! MPLS Gateway

 

R5 (config) # route-map GUEST_TO_BB permit 10

 R5 (config) # match ip address GUEST_TRAFFIC

R5 (config) #  set ip next-hop 203.0.113.1  ! Broadband Gateway

 

! Apply PBR to LAN-facing interface

R5 (config) # interface GigabitEthernet0/0

 R5 (config) # description LAN Interface

R5 (config) #  ip policy route-map ERP_TO_MPLS

R5 (config) #  ip policy route-map GUEST_TO_BB

 

Step-3. SD-WAN Policy Configuration (Conceptual)

On Cisco SD-WAN (Viptela), Fortinet Secure SD-WAN, or Versa — the principle is the same:

  • Classify apps (ERP, VoIP, Cloud)
  • Define SLA thresholds
  • Apply path preferences


Example: Cisco vManage-style config (pseudo)

Vmanage (config)# policy data-policy APP-ROUTING

Vmanage (config)#  sequence 10

Vmanage (config)#   match application ERP

Vmanage (config)#   action prefer MPLS

Vmanage (config)#  sequence 20

Vmanage (config)#   match application VoIP

Vmanage (config)#   action prefer-lowest-latency

Vmanage (config)#  sequence 30

Vmanage (config)#   match application O365 Salesforce

  Vmanage (config)# action local-internet-breakout

Vmanage (config)#  default-action pass

 

Vmanage (config)# policy sla-classes

Vmanage (config)#  class MPLS-SLA

Vmanage (config)#   latency 150

 Vmanage (config)#  loss 1

 Vmanage (config)#  jitter 30

Vmanage (config)#  class VoIP-SLA

 Vmanage (config)#  latency 100

Vmanage (config)#   loss 0.5

Vmanage (config)#   jitter 20

Vmanage (config)# apply-policy site-list ALL_BRANCHES data-policy APP-ROUTING


Summary:

In today’s global enterprise networks, performance, security and flexibility are key to meeting multiple application and compliance requirements. Take ShopWorld Inc..—a global retail company with HQ in New York and branches in Chicago, London and Mumbai—as an example. We can see how a network architect can combine VRF Lite, Policy-Based Routing (PBR) and SD-WAN to build an optimized hybrid WAN. The architecture ensures critical ERP traffic always takes low-latency MPLS links, guest Wi-Fi is isolated on broadband, VoIP follows the path with the best real-time performance, and cloud applications like Office 365 break out locally for speed. VRF Lite provides strong logical segmentation, keeping Finance traffic separate from corporate and guest networks. PBR enforces site-specific static routing policies like ERP-to-MPLS and guest-to-broadband even in smaller branches without full SD-WAN. SD-WAN overlays the entire WAN fabric, centrally manages traffic flows, dynamically adjusts routes based on link health and optimizes cloud connectivity. Together these technologies deliver a robust, secure and agile WAN that meets operational and regulatory requirements in a distributed multi-branch environment. This integrated design not only maximizes application performance but also simplifies policy enforcement, it’s a blueprint for future-proof networking.


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