why we use vrf and tell me for how many purpose it use..please tell me the full condition? thanx ja

[khanjahangir]

why we use vrf and tell me for how many purpose it use..please tell me the full condition?

thanx ja

[kcnajaf]

Hi Jahangir,

VRF satands for Virtual Routing and Forwarding. VRF is used when you want seperation in routing table with the router. You can have multiple instance of routing table on the same router with the help of VRF.

A trypical example would be ISP's using same router to route traffic for various customers and configure VRF to seperate the various customer traffics with the router.

Hope that helps.

Regards

Najaf

[blau grana]

Hi

I agree with Najaf, just want to add that primary use for VRF is MPLS VPN on PE routers.

Thanks to VRF you are able to create "logical router" for each customer terminated on that PE.

VRF can be used also without MPLS, it is called than VRF-lite.

Best Regards

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[PaulMM03209]

VRF works at layer 3 while VLAN is at layer 2.  The VLANs may communicate with each other if there is a router between and no VRF. For more https://www.cspsprotocol.com/what-is-vrf/

[Joseph W. Doherty]

(Although already correctly answered by other posters, sometimes describing the same concept a bit differently, helps in its understanding.)

A VRF is sort of, for L3, the equivalent of a L2's VLAN.  Just as L2 VLANs provide logical isolation of L2 domains on the same switch, a L3 VRF provides logical isolation of L3 networks on the same router.

Often the two most common reasons to use VRFs are to allow the use of overlapping IP addresses on the same physical L3 routing devices and/or to increase security.

One difference with VRFs, is you can, with configuration, allow traffic and/or routing information to pass between them.  You can effectively even provide something like the L3 equivalent of private VLANs (a L3 hub/core that can communicate with separate branch/edge networks, but those cannot communicate between themselves).

BTW, some vendors also support virtual routing, where a "whole" router becomes a logical thing, but these are not exactly the same as VRFs.  (Also such virtual routers may, themselves, support VRFs.)