VRF Technology – Virtual Routing and Forwarding Network Concept

Virtual Routing and Forwarding Network

VRF – Virtual Routing and Forwarding

VRF (Virtual Routing and Forwarding) is revolutionary foot print in Computer networking history that changed the concept of networking.VRF technology is first thing that introduce virtualisation concept in networking.

Virtual routing and forwarding(VRF) is network virtualisation technology that allow to create multiple virtual instances under one physical complement or device.Let’s take an example, in old day we were bund to create one routing table under one router and one physical interface can assign one IP only.

👉🏽VRF is a core technology of MPLS which allows a service provider to provide BGP routing to many customer VPNs while isolating each customer’s routing tables.

With help of VRF technology – Network administrator can create multiple routing table under one router.VRF manage multiple routing table in the same time and keep them isolated and running them independently. The other advantage of VFR is – Subnet overlapping , where service provider can use same IP address range for multiple customer without conflicting with each other.For example – you can use that same IP address assigned to two different interfaces on a router at the same time.

Service provider take the advantage of using VRF technology to isolate the customer network connection by creating a separate vpn on a Provider edge router (PE). The PE router creates one VRF table for each VPN that has a connection to a CE router. By using VRF,  service provide can manage multiple customer connection on same physical router and provide the a dedicated virtual network connection to customer router.

VRF used to create multiple virtual routing table in one physical router. VRFs are commonly used for MPLS deployments and MP-BGP, whereby service create Layer3 (or Layer2) VPNs services for customers and logically isolate them on physical router.

👉🏽 VRF’s act like VLANs for router that can support multiple network routing instance that exists in same physical router.Each VRF interface (Virtual Interface) on router is assigned to different customer network.VRFs are commonly used for MPLS deployments.

VRF Network
The above VRF diagram – A single physical router with three VRF’s.Each VRF in the example – VRF-1 , VRF-2 and VRF-3 are completely separate routing table running under on router.The IP address may overlap with routes in another VRF , but potentially we have possibility to use same IP address space for different customers having a separate VRFs.

Key Advantage of VRF

1. VRF is virtual technology allow to create multiple routing instate on one physical device.

2. VRF Can manage multiple routing table simultaneously.

3. VRF commonly used for MPLS deployments and MP-BGP.

4. VRF act like a virtual router with routing independent.

5. VRF allow to share the same IP address space with multiple customer without conflict


⚠️ Note –

According to Cisco portfolio – VRF are two types, VRF and VRF lite. The VRF is associated with MPLS technology in order to create MPLS VPN (Layer-3/Layer-2) to isolate different customers network and their routing table.

VRF Lite is VRF without MPLS is called VRF lite.VRF Lite means VRF without  the need to run MPLS in the network.  VRF Lite allows the network administrator to create multiple routing instances on the same routing device within the enterprise.

Author: Ronnie Singh

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