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Versatile Routing and Services with BGP: Understanding and Implementing BGP in SR-OS by Colin Bookham, Alcatel-Lucent

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Chapter 11

Looking Ahead

Given that BGP is so flexible and extensible, it's no surprise that it continues to evolve to encompass more NLRI and extend its applicability. This chapter discusses a few of the more significant emerging uses of BGP. It provides an overview of these technologies and how they might be used. It is not a product roadmap.

Ethernet VPN (EVPN)

A BGP MPLS Based Ethernet VPN (EVPN) (draft-ietf-l2vpn-evpn) provides virtual Layer-2 bridged connectivity between a set of CE routers. PE routers providing this service are interconnected using MPLS LSPs or IP tunneling techniques such as GRE (in this context sometimes referred to as Network Virtualization GRE or NVGRE) in exactly the same way that is currently used to provide Layer-2 or Layer-3 VPN services today.

In a conventional bridged service (VPLS), MAC learning is done in the data plane, but for EVPN, MAC learning is done in the control plane. PEs supporting the EVPN advertise MAC addresses learned from connected CEs together with an MPLS label using Multi-Protocol BGP. Control-plane learning offers significant benefits over data-plane learning, such as reducing the requirement to flood and helping to improve reconvergence times for certain failure scenarios. One other major benefit of control-plane learning is that it enables flow-based load-balancing of traffic to CEs that are dual-homed. Today dual-homed sites must work in active/standby mode using methods such as BGP Multi-Homing, STP, or Multi-Chassis LAG ...

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