VRF meaning Virtual Routing and Forwarding , is a technology implemented in the IP network routers that allows
multiple instances of a routing table to exist on the same router in the same time. Since each VRF is independent, the same IP subnet can exist in 2 different VRFs. Basically you can overlap one
IP address in 2 VRFs but without conflicting with each other. Even this is possible, I would not suggest doing so, unless you have a very good reason to do it.
VRF acts like a logical router, but while a logical router may include any routing tables, a VRF instance uses only a single routing table.in addition, VRF requires a forwarding table that designates the next hop for each data packet, a list of devices that may be called upon to forward the packet, and a set of rules and routing protocols that govern how the packet is forwarded. These tables prevent traffic from being forwarded outside a specific VRF path and also keep out traffic
a VRF is a quite complex topic but let's say that per say a VRF can be considered like a routing table generally separated from the global routing table (the one we are used to work with). Essentially the requirements for what the VRF (Virtual Routing and Forwarding) technology was implemented was to separate the networks in order to operate with VPN. If you imagine two routing table on the same device which generally cannot talk each other, you realise the potential for different customer to have their own private network working with a sort of "private" routing table. As you can imagine the concept of VRF has been heavily implemented and developed by the Service Providers for their customers and furtherly applied to MPLS. Keep in mind that even if MPLS and VRF are technologies that very well work together, they remain different and independent technologies.
When infact you will find the "VRF-lite" definition, this will refer to the solely use of VRFwith NO MPLS implementation.And generally it is not a so common choice in the modern SP networks anymore. I do believe that a good start point in uderstanding the VRF could be wikipedia!!!
Just a note to underline how the concept of VRF strictly embraces the concept of routing table.. You can think about the normal routing table you work with as a global VRF. Maybe it is oversimplified but it is not a wrong association
To start implementing VRF i would suggest to study first VRF-lite and then developing your knowledge/configurations over the wider MPLS field.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.