Genie's Tech Blog

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BGP RT Constrained Route Distribution

For Handling unnecessary processing of prefixes of RT which are not imported on the PE routers we use the feature called Route-Target Constraint. With Route Target Constraint (RTC), the RR sends only those VPN4/6 prefixes to the PE that the PE has VRF importing those specific route-targets. [More]

Inter-AS MPLS VPN - Back to Back VRF

Hello All, Today, We are going to discuss about one of the very common topics on Inter-AS MPLS VPN's i.e. Inter-AS MPLS VPNs with Back to Back VRF. We are already aware of how Intra-AS MPLS VPN's work. This has been discussed deeply in one of our previous posts (Link Below). http://blog.codergenie.com/blog/page/MPLS-VPN-Basic.aspx In Inter-AS VPN, Customers connect their sites across AS boundaries. The very first and basic type of Inter-AS deployment is Back to Back VRF. In this approach, the ASBR of both AS's connect each other through multiple sub-interfaces where in each sub-interface se... [More]

Inter-VRF Routing

Hello All, Today, I will be discussing about VRF-Lite and will also be discussing one of the designs using BGP which have been seen in real world deployments which is the Inter-VRF Routing. Lets first start by understanding what is VRF.  VRF: Virtual Router Forwarding, an IOS feature in which multiple forwarding tables are used, with the choice of which table to use is based upon additional data outside of a packet's IP header, such as the L3 input interface or an MPLS tag. VRF-Lite: An implementation of VRF on CE devices in which forwarding table selection is done based upon the L3 in... [More]

BGP-based VPLS Autodiscovery

Hello Everyone, I am back with yet another post on one of the topics which caught my interest on - VPLS Autodiscovery using BGP. Before we start digging in to it, lets first start by understanding what VPLS is? What is VPLS? Virtual - Multiple VPLSs can be offered over common packet switched network. Private - CE devices that belong to different VPLSs cannot interact LAN Service - CE devices that belong to given VPLS instance V, can interact through the SP network as if they were connected by a LAN. VPLS is an architecture which allows MPLS networks to provide Mu... [More]