In previous BGP policy lab exercises, we covered several mechanisms you can use to ensure your autonomous system is not leaking transit routes (because bad things happen when you do, particularly when your upstream ISP is clueless).

As you probably know by now, there’s always more than one way to get something done with BGP. Today, we’ll explore how you can use the NO_EXPORT community to filter transit routes.

Click here to start the lab in your browser using GitHub Codespaces (or set up your own lab infrastructure). After starting the lab environment, change the directory to policy/d-no-export and execute netlab up.

A while ago, Eric Chou invited me to a friendly chat in his Network Automation Nerds podcast.

The episode was published a few days ago; I hope you’ll enjoy listening to it.

In the first exercise in the IS-IS labs series, you configured IS-IS routing for IPv4. Before moving on to more complex topics, let’s explore the data structures IS-IS created to represent your network.

In the previous blog posts, we explored the simplest possible IBGP-based EVPN design and made it scalable with BGP route reflectors.

Now, imagine someone persuaded you that EBGP is better than any IGP (OSPF or IS-IS) when building a data center fabric. You’re running EBGP sessions between the leaf- and the spine switches and exchanging IPv4 and IPv6 prefixes over those EBGP sessions. Can you use the same EBGP sessions for EVPN?

TL&DR: It depends™.

netlab release 1.9.1 brings packet capture capabilities and numerous routing features:

• IS-IS route redistribution and IS-IS VRF instances
• RIPv2/Ripng route redistribution and VRF instances
• Configurable RIPv2/RIPng protocol timers

We also added support for Cisco IOSv layer-2 image. You’ll find more details in the release notes.

I spent a few days in a beautiful place with suboptimal Internet connectivity. The only thing I could do whenever I got bored (without waiting for the Internet gnomes to hand-carry the packets across the mountain passes) was to fix the BGP labs on a Ubuntu VM running on my MacBook Air (hint: it all works).

Big things first. I added validation to these labs:

• MD5 Passwords and GTSM
• Use BGP Timers and BFD to Speed Up BGP Convergence
• BGP Route Aggregation
• EBGP Sessions over IPv6 LLA Interfaces
• Establish an IBGP Session
• Build a Transit Network with IBGP
• Use BGP Route Reflectors
• Using No-Export Community to Filter Transit Routes

In the first exercise in the IS-IS labs series, you’ll configure IS-IS routing for IPv4. The basic configuration is trivial, but you’ll also have to tweak the defaults that most vendors got wrong (we’ll discuss why those defaults are wrong in the next lab exercises).

I also tried to make the IS-IS labs more than just lab exercises. Each exercise includes a bit of background information or IS-IS theory; this one describes generic OSI addresses (NSAPs) and router addresses (NETs).

When looking for the latest SR Linux container image, I noticed images with -arm-preview tags and wondered whether they would run on Apple Silicon.

TL&DR: YES, IT WORKS 🎉 🎉

Here’s what you have to do to make SR Linux work with netlab running on a Ubuntu VM on Apple silicon:

All our previous designs of the hub-and-spoke VPN (single PE, EVPN) used two VRFs for the hub device (ingress VRF and egress VRF). Is it possible to build a one-arm hub-and-spoke VPN where the hub device exchanges traffic with the PE router over a single link?

TL&DR: Yes, but only on some devices (for example, Cisco IOS or FRRouting) when using MPLS transport.

Here’s a high-level diagram of what we’d like to achieve:

In the previous BGP load balancing lab exercise, I described the BGP Link Bandwidth attribute and how you can use it on EBGP sessions. This lab moves the unequal-cost load balancing into your network; we’ll use the BGP Link Bandwidth attribute on IBGP sessions.