Category: MPLS VPN

BGP AS Numbers for a Private MPLS/VPN Backbone

One of my readers was building a private MPLS/VPN backbone and wondered whether they should use their public AS number or a private AS number for the backbone. Usually, it doesn’t matter; the deciding point was the way they want to connect to the public Internet:

We also plan to peer with multiple external ISPs to advertise our public IP space not directly from our PE routers but from dedicated Internet Routers, adding a firewall between our PEs and external Internet routers.

They could either run BGP between the PE routers, firewall, and WAN routers (see BGP as High-Availability Protocol for more details) or run BGP across a bump-in-the-wire firewall:

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Creating VRF Lite Labs With netlab

I always found VRF lab setups a chore. On top of the usual IPAM tasks you have to create VRFs, assign route targets and route distinguishers, do that on every PE-router in your lab… before you can start working on interesting things.

I tried to remove as much friction as I could with the netlab VRF configuration module – let me walk you through a few simple examples1 which will also serve to illustrate the VRF configuration differences between Cisco IOS and Arista EOS.

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netlab MPLS Support

netlab release 1.2.0 adds full-blown MPLS and MPLS/VPN support:

It’s never been easier to build full-blown MPLS/VPN labs ;)… if you’re OK with using Cisco IOS or Arista EOS. Please feel free to submit a PR to add support for other platforms.

You might want to start with the VRF tutorial to see how simple it is to define VRFs, and follow the installation guide to set up your lab – if you’re semi-fluent in Linux (and don’t care about data plane quirks), the easiest option would be to run Arista cEOS.

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Reviving Old Content, Part 3

We had the usual gloomy December weather during the end-of-year holidays, and together with the partial lockdown (with confusing ever-changing rules only someone in Balkans could dream up) it managed to put me in OCD mood… and so I decided to remove broken links from the old blog posts.

While doing that I figured out how fragile our industry is – I encountered a graveyard of ideas and products that would make Google proud. Some of those blog posts were removed, I left others intact because they still have some technical merits, and I made sure to write sarcastic update notices on product-focused ones. Consider those comments Easter eggs… now go and find them ;))

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Not So Fast Ansible, Cisco IOS Can’t Keep Up…

Remember how earlier releases of Nexus-OS started dropping configuration commands if you were typing them too quickly (and how it was declared a feature ;)?

Mark Fergusson had a similar experience on Cisco IOS. All he wanted to do was to use Ansible to configure a VRF, an interface in the VRF, and OSPF routing process on Cisco CSR 1000v running software release 15.5(3).

Here’s what he was trying to deploy. Looks like a configuration straight out of an MPLS book, right?

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EVPN Is More than VPLS on Steroids

Tiziano Tofoni wrote a lengthy comment on my EVPN in small data center fabrics blog post continuing the excellent discussion we started over a beer last October. Today, I’ll address the first part:

I think that EVPN is an excellent standard for those who love Layer 2 (L2) services; we may say that it is an evolution of the implementation of the VPLS service, which addresses some limits in the original standard (RFCs 4761 and 4762).

I might be missing something, but in my opinion, there’s no similarity between EVPN and VPLS (apart from the fact that they’re trying to solve the same problem).

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Automation Win: MPLS/VPN Service Deployment

I always encourage the students attending the Building Network Automation Solutions online course to create solutions for problems they’re facing in their networks instead of wasting time with vanilla hands-on assignments.

Francois Herbet took the advice literally and decided to create a solution that would configure PE-routers and create full-blown device configurations for CE-routers.

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Generating OSPF, BGP and MPLS/VPN Configurations from Network Data Model

Over a month ago I decided to create a lab network to figure out how to solve an interesting Inter-AS MPLS/VPN routing challenge. Instead of configuring half a dozen routers I decided to develop a fully-automated deployment because it will make my life easier.

I finally got to a point where OSPF, LDP, BGP (IPv4 and VPNv4) and MPLS/VPN configurations are created, deployed and verified automatically.

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