The topic of this post is Layer 3 VPN (L3VPN or VPRN as we call it in SROS) configuration, and I decided to kill two birds with one stone by inviting Juniper vMX to our cozy SROS environment.

The BGP/MPLS VPN (RFC 4364) configuration will undergo the following milestones:

  • PE-PE relationship configuration with VPN IPv4 address family introduction
  • PE-CE routing configuration with both BGP and OSPF as routing protocols
  • Export policy configuration for advertising VPN routes on PE routers
  • AS override configuration
  • and many more

We’ll wrap it up with the Control Plane/Data Plane evaluation diagrams which help a lot with understanding the whole BGP VPN mechanics. Take your seats, and buckle up!

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In the first part of this BGP tutorial we prepared the ground by configuring eBGP/iBGP peering. We did a good job overall, yet the plain BGP peering is not something you would not normally see in production. The power of BGP is in its ability for granular management of multiple routes from multiple sources. And the tools that help BGP to handle this complex task are BGP policies at their full glory.

In this part we will discuss and practice:

  • BGP export/import policies for route advertisement/filtering
  • BGP communities operations
  • BGP routes aggregation: route summarization and the corresponding aggregate and atomic-aggregate path attributes

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There is no way I would leave you without covering configuration steps for one of the most versatile, scalable and robust internet protocols also known as BGP. And here it is - BGP configuration guide for Nokia (Alcatel-Lucent) Service Routers.

As with the OSPF configuration tutorial I will cover the configuration process for various BGP scenarios along with the verification and troubleshooting steps bundled with colorful figures, detailed code snippets and useful remarks.

BGP is so huge that I had no other option but to write about it in several parts:

Part 1 is dedicated to basic eBGP/iBGP configuration. We will practice with common BGP configuration procedures at first, then learn how to export routes into BGP process and prevent unnecessary route reflection by means of split-horizon over eBGP links.

Next we go over iBGP configuration to spread the eBGP learned routes across the Autonomous Systems. I will explain the necessity of having a full-mesh iBGP topology and the use of the next-hop-self command for iBGP peers.

It’s a perfect time to configure some BGP, right?

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Author's picture

Roman Dodin

Eagerness to learn & passion to share

Netdevops @ Nuage Networks

Russia