In the enterprise world, resources are frequently optimized to maximize the return on infrastructure investments . Therefore, the more benefits we can obtain from our equipment, the better we can justify the investment cost.
In traditional enterprise environments, a router is typically allocated for each zone , area, or service, such as Core, Edge (Internet), Voice Gateway , WAN Site-to-Site , etc. This results in high costs for each hardware upgrade or renewal, both in terms of capital expenditures ( Capex) and operating expenses (Opex) , as it involves maintaining multiple routers and continuing to expand with new equipment as Layer 3 connectivity needs arise. Today, we can leverage the fact that many Cisco routers offer a feature called VRF-Lite . This capability allows a physical router to be logically divided into multiple contexts or VRFs, which can then be independently assigned to different Layer 3 zones or services.
What is VRF-Lite ?
Virtual Routing and Forwarding (VRF) is a mechanism used by service providers that allows them to segment customer IP traffic using MPLS encapsulation. This functionality enables the management of diverse contexts, where each context behaves as an independent router , allowing the use of a single router to serve a number of clients without IP overlap and ensuring independence between each client .
In enterprise environments, the use of contexts is called VRF-Lite . This allows users to have the benefits of ISP-provided routers without the need to implement MPLS . Each router can contain a finite number of contexts or VRFs, and their use will be limited by software, hardware , or licensing requirements.
Each router will have a global routing table and an independent routing table for each VRF created (context) ; this guarantees IP traffic privacy, support for IP address overlap (useful in the event of an inter-company merger), IP segmentation by traffic type such as voice, video, data (Financial, Human Resources, Operations, Data Center, etc.).
Within each VRF, we can continue to use static or dynamic routing just as it is done in the global plane of a traditional router ; therefore, it allows adaptation to any network connectivity environment; these contexts can be associated with interfaces or sub-interfaces, thus further optimizing resources at the interface level; it also has support for both IPv4 and IPv6 .
Dividing a physical router into several virtual ones allows us to reduce costs in hardware , space, power consumption, and cabling, while also improving security in IP segmentation . However, we must not forget that the equipment becomes a critical point in the operation, as we will have a single point of failure. Therefore , we must consider its respective backup or redundant equipment in order to mitigate any interruption event.
Written by : Hans Francisco Chete. Level II Engineer at ITS InfoCom
