IP Data Packet Mapping onto MPLS LSPs Overview

IP packets are mapped onto LSPs by one of the following methods:

When IP packets arrive at the ingress LER, they are looked up in the relevant IP forwarding table and then are forwarded into an LSP. Every IP route eventually points to an IP interface. The IP interface contains IP attributes that affect how the IP packet is forwarded. IPv4 routes point only to IPv4 interfaces and IPv6 routes point only to IPv6 interfaces.

Because IP routes cannot point directly to MPLS major interfaces, MPLS automatically creates up to four dynamic IP shared interfaces that are stacked on each MPLS major interface. When you issue the mpls command in Interface Configuration mode, the interfaces are created dynamically and provide the interfaces an IP route needs to point to. You can specify a profile (created with the profile command) to configure attributes for these interfaces with the mpls create-dynamic-interfaces command. You can use the same command to enable or disable the creation of specific interface types or all types.

Each dynamic interface is one of the following types:

IPv6 must be enabled in the parent virtual router so that IPv6 dynamic interfaces can be created over MPLS interfaces. Otherwise, IPv6 VPNs do not work correctly,

All VPN traffic sent onto or received from the same layer 2 interface uses the same IPv4 VPN or IPv6 VPN interface. Consequently, any policy attached to the interface applies to all that VPN traffic.

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