Contents
What is the use of route target?
Route targets are used to indicate which VRFs a VPN prefix should be imported into. In fact, when a PE router exports a VPN prefix, we can actually tag it with multiple route-targets, which allows us to import that prefix into multiple routing tables around our ISP network!
What is route target import and export?
A route-target extended community, or route target, is a type of BGP extended community that you use to define VPN membership. The route target appears in a field in the update messages associated with VPN-IPv4. You create route-target import lists and route-target export lists for each VRF.
What is the purpose of route distinguisher?
The route distinguisher has only one purpose: to make IPv4 prefixes globally unique. It is not used for IP forwarding by the provider’s core (non-edge) routers (within the MPLS cloud), but it is used by the edge routers to identify which VPN a packet belongs to.
What is the difference between route distinguisher and route target?
Whereas route distinguishers are used to maintain uniqueness among identical routes in different VRFs, route targets can be used to share routes among them.
What is the main function of VRF Lite?
VRF-lite is a feature that enables a service provider to support two or more VPNs, where IP addresses can be overlapped among the VPNs. VRF-lite uses input interfaces to distinguish routes for different VPNs and forms virtual packet-forwarding tables by associating one or more Layer 3 interfaces with each VRF.
How do I export my router target identifier?
This exporting is done by the PE routers connecting to the CE routers. The CE routers in this example our peering via eBGP with the PE routers inside of a VRF. The VRF configuration on the PE routers is what indicates the Router Target identifier to export.
When to use route distinguishers and Route targets?
Route Targets. Whereas route distinguishers are used to maintain uniqueness among identical routes in different VRFs, route targets can be used to share routes among them. We can apply route targets to a VRF to control the import and export of routes among it and other VRFs.
Where do I get my route target information?
The support is through a new address family rtfilter for both VPNv4 and VPNv6. The Route Target (RT) filtering information is obtained from the VPN RT import list from all the VRFs on the PE router.
What is the purpose of Route target constraint?
Route Target Constraint 1 Introduction. This document describes a mechanism whereby the exchange of VPNv4 and VPNv6 prefixes towards Provider Edge (PE) routers is reduced to the minimum necessary. 2 Purpose of Route Target Constraint. 3 Behavior Without RTC. 4 RTC Configuration 5 Behavior of RTC.