# netlab Published articles for netlab. This is one page of public article previews, not the complete archive. Follow Next page to continue. Summaries are not the original full articles. ## Sunsetting netlab Vagrant/libvirt provider DevFeed: [Sunsetting netlab Vagrant/libvirt provider]() Original publisher: [Read original article]() Published: 2026-09-17T05:51:00Z Content type: article Language: en Sources: [ipSpace.net blog]() Topics: [Vagrant](), [Infrastructure as code](), [Orchestration](), [Containerlab topology](), [Oracle-VM-VirtualBox]() Tags: [change](), [containers](), [infrastructure](), [infrastructure-as-code](), [netlab](), [orchestration](), [vagrant](), [virtualbox]() ### AI overview The netlab project is sunsetting its Vagrant/libvirt provider after the vagrant-libvirt plugin became effectively unmaintained and HashiCorp announced the closure of Vagrant Cloud by the end of 2026. Existing support and tests will remain for now, but no new libvirt features or device integration tests are planned; containerlab will become the primary orchestration path. ### Source excerpt When I started the netlab project, Vagrant was the go-to tool if you wanted to build a virtual environment described in a text configuration file (an idea popularized as infrastructure-as-code). It wasn't ideal for what we were doing, but a tool rarely does a great job when used far away from its intended use case. netlab initially supported Vagrant with VirtualBox, quickly adding support for KVM/libvirt through the vagrant-libvirt plugin. Life was good... until it wasn't. Read more ... ## MPLS/VPN with SR-MPLS Core DevFeed: [MPLS/VPN with SR-MPLS Core]() Original publisher: [Read original article]() Published: 2026-09-15T05:45:00Z Content type: article Language: en Sources: [ipSpace.net blog]() Topics: [SR-MPLS](), [MPLS VPN](), [networking](), [BGP](), [IS-IS](), [Network](), [GitHub]() Tags: [bgp](), [devices](), [github](), [is-is](), [mpls](), [mpls-vpn](), [netlab](), [sr-mpls](), [vpn]() ### AI overview This article explains how to build and test an MPLS/VPN service over an SR-MPLS core. It describes the required lab topology changes, including enabling MPLS/VPN, disabling LDP, configuring PE routers with IS-IS, SR-MPLS, BGP, MPLS, and VRF modules, and moving PE-to-host links into tenant VRFs. It also outlines how to run the lab using GitHub Codespaces, an Arista cEOS container, and netlab. ### Source excerpt As we discussed in the BGP-Free Core with SR-MPLS blog post, SR-MPLS works as a drop-in replacement for the traditional MPLS control plane. No wonder it works well (when properly implemented) with MPLS/VPN services - the second "fun" scenario in my ITNOG10 Segment Routing workshop. It uses the same topology as the BGP-Free Core scenario: Simplest possible MPLS/VPN network with SR-MPLS core Read more ... ## Configuring Management IP Addresses to Virtual Network Devices DevFeed: [Configuring Management IP Addresses to Virtual Network Devices]() Original publisher: [Read original article]() Published: 2026-09-14T05:29:00Z Content type: article Language: en Sources: [ipSpace.net blog]() Topics: [networking](), [configuration](), [Orchestration](), [Vagrant](), [Cloud](), [ssh]() Tags: [cli](), [cloud](), [devices](), [dhcp](), [ip](), [ipv4](), [ipv6](), [management](), [netlab](), [network](), [networking](), [orchestration](), [server](), [ssh]() ### AI overview The article explains how to assign predictable management IP addresses to virtual network devices. It contrasts manual console-based setup with automated assignment through orchestration, containers, DHCPv4/DHCPv6, custom Vagrant boxes, and IPv6 mechanisms such as SLAAC. ### Source excerpt It goes without saying that if you want to configure (virtual) network devices with any semi-sane configuration mechanism1, the device must have a working IP address. Here's the time-honored method2 to assign an IP address to a virtual network device: Start the virtual machine (using a GUI)3 Open a new window: either a telnet session to the virtual console port or a full-blown virtual console (GUI) session. Manually configure the IP address, the SSH server, and the user credentials on the first interface. Read more ... ## BGP-Free Core with SR-MPLS DevFeed: [BGP-Free Core with SR-MPLS]() Original publisher: [Read original article]() Published: 2026-09-03T05:30:00Z Content type: article Language: en Sources: [ipSpace.net blog]() Topics: [SR-MPLS](), [BGP](), [networking](), [Network](), [Routing (disambiguation)](), [Containers](), [Linux](), [GitHub]() Tags: [bgp](), [containers](), [edge](), [examples](), [github](), [is-is](), [linux](), [mpls](), [netlab](), [network](), [router](), [routing](), [sr-mpls]() ### AI overview This article demonstrates how to build a BGP-free transport core with SR-MPLS using netlab. It describes a lab topology with IS-IS, BGP, Linux container hosts, and PE routers, then shows how SR-MPLS labels provide end-to-end connectivity without BGP routes on the core router. ### Source excerpt The beauty of SR-MPLS is that it's a drop-in replacement for the traditional (LDP- or RSVP-based) MPLS control plane. For example, you could replace LDP with SR-MPLS in a network using MPLS to implement a BGP-free transport core, and it just keeps working. This scenario was the first "fun" scenario in the ITNOG10 Segment Routing workshop. The core network uses the same topology as in the previous examples; I added two hosts and BGP routing. Simplest possible network using a BGP-free core Read more ... ## Networking Aspects of Running VMs in Containers DevFeed: [Networking Aspects of Running VMs in Containers]() Original publisher: [Read original article]() Published: 2026-09-02T05:44:00Z Content type: article Language: en Sources: [ipSpace.net blog]() Topics: [Containers](), [virtualization](), [networking](), [Linux](), [Orchestration]() Tags: [bridge](), [containers](), [docker](), [ethernet](), [linux](), [netlab](), [networking](), [podman](), [qemu](), [virtual-machines](), [virtualization]() ### AI overview The article explains how vrnetlab and a containerlab fork package virtual machines, especially network devices, as containers so container orchestration can provision network topologies. It focuses on connecting QEMU virtual network interfaces, Linux tap interfaces, bridges, and container veth pairs, including why data-plane and management interfaces require different handling. ### Source excerpt The vrnetlab project and its containerlab fork implement a wonderful idea: let's package virtual machines (primarily network devices that cannot be containerized) as containers to use reliable orchestration tools like containerlab to provision network topologies. That approach might have a few drawbacks (depending on how the container images are built), but the obvious elephant in the room is: how do you make the virtual network plumbing work? Read more ... ## Using netlab in Software Testing with Dinesh Dutt DevFeed: [Using netlab in Software Testing with Dinesh Dutt]() Original publisher: [Read original article]() Published: 2026-08-28T06:26:00Z Content type: article Language: en Sources: [ipSpace.net blog]() Topics: [Software Testing](), [networking](), [software-development](), [Ansible](), [Vagrant]() Tags: [ansible](), [development](), [netlab](), [network](), [networking](), [podcast](), [software](), [software-development](), [software-gone-wild](), [software-testing](), [testing]() ### AI overview This article introduces Episode 208 of Software Gone Wild, a conversation about using netlab to test network management software. It discusses how netlab helps Stardust Systems test new SuzieQ features, along with related history involving Vagrant and Ansible. ### Source excerpt I know a few software development companies use netlab to test their network management software (and contribute back to netlab - thanks a million!), and I always wanted to chat about that. As I have known Dinesh Dutt for ages, it wasn't hard to decide who to invite to have that chat with ;) As it turns out, it's dangerous to put Dinesh1 and me in the same (virtual) room - we were all over the place, from the ancient history of Vagrant in networking labs to the recent Ansible woes, but we did manage to cover how netlab helps Stardust Systems test new SuzieQ features. Read more ... ## Yak-Shaving netlab Podman Support DevFeed: [Yak-Shaving netlab Podman Support]() Original publisher: [Read original article]() Published: 2026-08-27T05:30:00Z Content type: article Language: en Sources: [ipSpace.net blog]() Topics: [Command-line interface](), [Orchestration](), [Docker](), [Ubuntu](), [Server]() Tags: [cli](), [docker](), [netlab](), [orchestration](), [podman](), [server](), [ubuntu]() ### AI overview The article describes the work required to make netlab support Podman as a runtime. It covers containerlab runtime configuration, Ubuntu-related issues, sudoless operation, Podman's socket-based API, installation automation, Docker-compatible commands, and differences in container visibility between Podman and Docker. ### Source excerpt Long, long time ago, in a long-forgotten PR adding support for Cumulus VX Ignite runtime, an off-the-cuff remark was made saying, "and this is how you use netlab with Podman". That remark was quietly sitting in the documentation for years until someone (A) tried to use Podman and (B) found enough time to report that it doesn't work with netlab. I don't know what that tells us: either very few people use Podman, or nobody (apart from a notable exception) cares enough to spend a few minutes telling us stuff doesn't work1. Anyway, based on Joey Buiteweg's wonderful research, I was able to put together a working solution pretty quickly, but it did involve a lot of yak shaving (more bovine details). Read more ... ## Multivendor SR-MPLS DevFeed: [Multivendor SR-MPLS]() Original publisher: [Read original article]() Published: 2026-08-25T05:44:00Z Content type: tutorial Language: en Sources: [ipSpace.net blog]() Topics: [SR-MPLS](), [networking](), [Routing (disambiguation)](), [IS-IS](), [GitHub]() Tags: [github](), [installation](), [is-is](), [mpls](), [netlab](), [network](), [routing](), [sr-mpls]() ### AI overview This tutorial demonstrates a multivendor SR-MPLS network built with netlab using Arista EOS, FRRouting, and SR Linux. It explains vendor-specific Segment Routing Global Block ranges, prefix segments, and MPLS LFIB label swapping, then outlines how to launch the lab through GitHub Codespaces. ### Source excerpt Summer is almost over, and it's time to resume regular programming with the next example from the Segment Routing workshop I had at ITNOG10: multi-vendor SR-MPLS. I used the same lab topology as in the previous examples but deployed Arista EOS on PE1, FRRouting on P, and SR Linux on PE21 Read more ... ## Arista cEOS Does Not Apply ACLs to Control-Plane Traffic DevFeed: [Arista cEOS Does Not Apply ACLs to Control-Plane Traffic]() Original publisher: [Read original article]() Published: 2026-08-24T05:20:00Z Content type: opinion Language: en Sources: [ipSpace.net blog]() Topics: [Network](), [BGP](), [Containers](), [Finite-state machine](), [configuration]() Tags: [bgp](), [containers](), [netlab](), [network](), [release](), [security](), [testing]() ### AI overview The article reports that Arista cEOS containers do not apply inbound ACLs to control-plane traffic or to traffic sent to the container's own IP addresses. This behavior differs from Arista vEOS virtual machines and can cause BGP connectivity tests using ACLs to produce unexpected results. ### Source excerpt When someone starts singing the Use Digital Twins to Test Your Network hymn (or, more recently, tells you how AI agents can do that to validate their ideas), ask them about these minor details. If they persist, point them (not that it would help) to this long list of gotchas. That list just got longer: Arista cEOS container does not apply inbound ACLs to control-plane traffic (Arista vEOS VM does). Read more ... ## The Never-Ending IPv6 Loopback Prefix Saga DevFeed: [The Never-Ending IPv6 Loopback Prefix Saga]() Original publisher: [Read original article]() Published: 2026-08-17T06:02:00Z Content type: article Language: en Sources: [ipSpace.net blog]() Topics: [Network](), [Hardware](), [datacenter](), [BGP]() Tags: [bgp](), [datacenter](), [hardware](), [ios](), [ipv6](), [is-is](), [netlab](), [network](), [ospf](), [vxlan]() ### AI overview The article examines the IPv6 loopback-prefix problem in high-speed routers and data-center switches. OSPFv3 requires loopbacks to be advertised as /128s, which can increase forwarding hardware demands when /64 addressing is preferred. It compares vendor behaviors and suggests IS-IS or BGP as possible alternatives. ### Source excerpt Remember the sage advice to simplify your life and use the IPv6 /64 prefixes everywhere? Not only does it make your life simpler (and wastes immesuarably less address space than the crazy "let's assign /64 to every device" stupidity), it also reduces the hardware requirements in your high-speed routers layer-3 switches. You see, doing lookups on 64 bits uses half the silicon it takes to do lookups on 128 bits. Alas, some people never got the memo. OSPFv3 standard clearly states in one of the bullets in section 4.4.3.9 that the loopback prefixes should always be advertised as /128s regardless of what's configured on the interface. Read more ... ## Compress netlab Lab Topologies with Dot Notation DevFeed: [Compress netlab Lab Topologies with Dot Notation]() Original publisher: [Read original article]() Published: 2026-08-12T05:55:00Z Content type: article Language: en Sources: [ipSpace.net blog]() Topics: [Python](), [YAML](), [BGP]() Tags: [bgp](), [blog](), [blog-post](), [netlab](), [post](), [python]() ### AI overview An article about using Python Box dotted notation to make netlab lab topology definitions easier to read and more concise, including examples in YAML for BGP routers and IPv4 links. ### Source excerpt netlab is using the Python Box library to make the code easier to read1. When I started the project, I hated the way you fetch values from Python dictionaries with stuff like node['ospf']['area']; Python Box lets you write node.ospf.area. Even better2, you can tell Python Box to create intermediate dictionaries as needed. node.ospf.area = 1 will automatically create the node.ospf dictionary. But wait, there's more (yes, we're getting to the topic of today's blog post): Box lets you use the same dotted notation in YAML files. Read more ... ## On ACLs and AI-Generated Device Configurations DevFeed: [On ACLs and AI-Generated Device Configurations]() Original publisher: [Read original article]() Published: 2026-08-11T05:11:00Z Content type: opinion Language: en Sources: [ipSpace.net blog]() Topics: [Artificial Intelligence]() Tags: [ai](), [driving](), [netlab](), [qos](), [youtube]() ### AI overview The article introduces a NetworkAutoMagic episode discussing ACL complexity, QoS, and the pitfalls of AI-generated network device configurations, with related notes and video options mentioned. ### Source excerpt Last Friday, I had a lovely chat with Steinn Bjarnarson and Urs Baumann, resulting in the NetworkAutoMagic episode 11. We couldn't avoid mentioning netlab, the seven layers of ACL hell (which is still balmy compared to the QoS hell), and the gotchas of AI-generated device configurations. Fortunately, I don't have to go into more details; Steinn published extensive notes, and if you don't feel like listening to us while driving, you can waste time watching us on YouTube. ## netlab 26.08: ArcOS, VPP (FD.io), ACLs, and DNS DevFeed: [netlab 26.08: ArcOS, VPP (FD.io), ACLs, and DNS]() Original publisher: [Read original article]() Published: 2026-08-10T09:58:00Z Content type: release Language: en Sources: [ipSpace.net blog]() Topics: [Release notes](), [networking](), [Containers](), [configuration](), [Routing (disambiguation)](), [Authorization]() Tags: [access-control](), [configuration](), [dns](), [getting-started](), [github](), [gre](), [installation](), [ipv4](), [ipv6](), [netlab](), [podman](), [release](), [release-notes](), [routing]() ### AI overview netlab 26.08 adds ArcOS support, VPP with FRR or BIRD control planes, SONiC containers, IPv4/IPv6 access control lists, DNS client and server configuration, GRE and WireGuard tunnel support, and Podman support for the clab provider. The article also notes bug fixes, configuration-template changes, upgrade guidance, and documentation for new users. ### Source excerpt netlab release 26.08 brings a few humongous additions: ArcOS support by @roc-ops VPP (FD.io) with FRR or BIRD control plane by @jbemmel SONiC containers (also by @roc-ops) IPv4/IPv6 access control lists in the routing module by @DanPartelly But wait, there's more: Read more ... ## netlab 26.07: GRE, Wireguard, Graceful Restart, and Scale-Out Labs DevFeed: [netlab 26.07: GRE, Wireguard, Graceful Restart, and Scale-Out Labs]() Original publisher: [Read original article]() Published: 2026-07-13T06:23:00Z Content type: release Language: en Sources: [ipSpace.net blog]() Topics: [releases](), [BGP](), [Server](), [evpn](), [VXLAN](), [configuration](), [GitHub]() Tags: [bgp](), [configuration](), [evpn](), [getting-started](), [github](), [gre](), [guide](), [installation](), [netlab](), [ospf](), [policy](), [release](), [releases](), [router](), [upgrade](), [vxlan]() ### AI overview The netlab 26.07 release adds scale-out labs through a multiserver plugin, GRE and WireGuard tunnel support, graceful restart capabilities, BGP policy roles, and expanded BIRD, FortiOS, MikroTik RouterOS, and OpenBSD functionality. It also removes the VirtualBox provider, makes BIRD v3 the default, and changes MikroTik RouterOS 7 BGP template syntax. ### Source excerpt The highlights of netlab release 26.07 include: The multiserver plugin by @muddyblack distributes containerlab devices across multiple servers. The GRE tunnel plugin supports GRE tunnels on Cisco IOS, FRR, VyOS, and Junos (vSRX and vJunos-router) (most device implementations done by @ssasso and @jbemmel). The WireGuard tunnel plugin by @jbemmel supports WireGuard tunnels on FRR. The bgp.session plugin and the OSPF module support graceful restart on Arista EOS, BIRD, FortiOS, and FRR (by @jbemmel and @a-v-popov) The bgp.policy plugin supports the bgp.role attribute on FRR and BIRD (by @jbemmel). But wait, there's more ;) Read more ... ## netlab: 2000 Pull Requests Later ;)) DevFeed: [netlab: 2000 Pull Requests Later ;))]() Original publisher: [Read original article]() Published: 2026-07-09T10:29:00Z Content type: news Language: en Sources: [ipSpace.net blog]() Topics: [pull-requests](), [GitHub](), [Python](), [bug]() Tags: [bug](), [contributed](), [github](), [netlab](), [pull-requests](), [python]() ### AI overview The netlab GitHub repository has reached 2,000 merged or closed pull requests. The article thanks contributors, bug reporters, question askers, and others who helped the Python learning project grow. ### Source excerpt Jeroen van Bemmel noticed an interesting fact yesterday evening: the netlab GitHub repository has 2000 merged/closed pull requests. I never expected the tiny "let's learn Python while working around the complexities of Vagrantfile" project to get this far ;)) Thanks a million to everyone who contributed, reported a bug, asked a question, or helped us spread the word. You rock 🤗 ## Worth Reading: More VXLAN and EVPN Labs DevFeed: [Worth Reading: More VXLAN and EVPN Labs]() Original publisher: [Read original article]() Published: 2026-07-06T05:44:00Z Content type: opinion Language: en Sources: [ipSpace.net blog]() Topics: [evpn](), [VXLAN]() Tags: [evpn](), [evpn-designs](), [free](), [journey](), [netlab](), [vxlan](), [worth-reading]() ### AI overview The article highlights Ali Bahadır Coşkun's progress through free netlab-powered EVPN/VXLAN labs, including basic EVPN control-plane work, VXLAN/IRB/anycast exercises, and available lab designs. ### Source excerpt Ali Bahadır Coşkun continued his EVPN/VXLAN journey. Using the free netlab-powered EVPN/VXLAN labs, he finished the basic EVPN/VXLAN lab (adding EVPN control plane to VXLAN underlay), and then completed the whole VXLAN/IRB/anycast saga. Want to do something similar? The free EVPN/VXLAN lab exercises include six VXLAN labs, almost a dozen EVPN labs, and a few EVPN designs. I might add a lab or two during the summer break. ## Getting Started with netlab @ Cisco DevNet DevFeed: [Getting Started with netlab @ Cisco DevNet]() Original publisher: [Read original article]() Published: 2026-06-29T05:23:00Z Content type: opinion Language: en Sources: [ipSpace.net blog]() Topics: [Cisco](), [Tool](), [Documentation]() Tags: [blog](), [cisco](), [getting-started](), [interview](), [netlab](), [video]() ### AI overview A Cisco DevNet channel published an hour-long interview with Suresh Vina introducing netlab. The article recommends the video to people new to netlab and notes that netlab.tools documentation received more weekly visits than the ipspace.net blog for the first time. ### Source excerpt Cisco DevNet channel has published an hour-long Getting Started with netlab interview with Suresh Vina, resulting in netlab.tools documentation having more weekly visits than ipspace.net blog for the first time. Thanks a million ;)) If you're new to netlab, I hope you'll enjoy the video. If you have any follow-up questions, don't hesitate to start a discussion. ## SR-MPLS with OSPFv2 DevFeed: [SR-MPLS with OSPFv2]() Original publisher: [Read original article]() Published: 2026-06-15T06:12:00Z Content type: tutorial Language: en Sources: [ipSpace.net blog]() Topics: [SR-MPLS](), [networking](), [Routing (disambiguation)](), [Protocol (disambiguation)](), [IS-IS](), [GitHub]() Tags: [container](), [github](), [is-is](), [mpls](), [netlab](), [ospf](), [protocol](), [routing](), [sr-mpls]() ### AI overview A hands-on tutorial showing how to configure and inspect SR-MPLS over OSPFv2 with netlab. It explains the OSPFv2 opaque LSAs used to advertise SR-MPLS information and notes that the resulting MPLS forwarding table matches the comparable IS-IS example. ### Source excerpt I started my part of the Segment Routing workshop @ ITNOG10 exploring SR-MPLS with IS-IS (simple SR-MPLS, dual-stack SR-MPLS, SR-MPLS over unnumbered IPv4 interfaces). Next step: let's change the routing protocol to OSPF while using the same network topology: Read more ... ## Using netlab to Configure Live Devices DevFeed: [Using netlab to Configure Live Devices]() Original publisher: [Read original article]() Published: 2026-06-11T06:02:00Z Content type: article Language: en Sources: [ipSpace.net blog]() Topics: [Automation](), [Network](), [configuration](), [YAML](), [NetBox](), [Ansible]() Tags: [automation](), [configuration](), [documentation](), [netlab](), [network](), [yaml]() ### AI overview The article examines whether netlab could eventually configure devices in a live network. It identifies hurdles including missing feature and IPAM integrations, incomplete configuration generation, difficulty merging changes safely, assumptions about unconfigured devices, and the limitations of representing a production network in one YAML file. ### Source excerpt Leo Fleskes sent me an interesting question after reading my Generate Partial Device Configurations with netlab blog post: What is stopping us from eventually, given enough usage and coverage, using netlab to configure devices in the live network? In theory, nothing. In practice, you might hit a few hurdles: Read more ... ## netlab 26.06: OSPFv3 on FortiOS, MPLS/VPN on SR Linux DevFeed: [netlab 26.06: OSPFv3 on FortiOS, MPLS/VPN on SR Linux]() Original publisher: [Read original article]() Published: 2026-06-08T06:13:00Z Content type: release Language: en Sources: [ipSpace.net blog]() Topics: [MPLS VPN](), [Ubuntu](), [Vagrant](), [Script]() Tags: [bugs](), [getting-started](), [github](), [guide](), [improvements](), [installation](), [mpls-vpn](), [netlab](), [release](), [ubuntu](), [upgrade](), [vagrant]() ### AI overview The netlab 26.06 release adds OSPFv3 support on FortiOS and MPLS/VPN support on SR Linux. It also updates installation compatibility for Ubuntu 26.04, includes Vagrant 2.4.9, and contains other improvements and bug fixes. ### Source excerpt netlab release 26.06 adds OSPFv3 support on FortiOS (by @a-v-popov) and MPLS/VPN support on SR Linux. We also ensured the installation scripts work on Ubuntu 26.04 (everything else was OK) and updated the installed Vagrant version to 2.4.9 (we're not using new Vagrant features; you don't have to upgrade it in an existing installation). Other than that, we added a few improvements and squashed a number of bugs. Upgrading or Starting from Scratch? To upgrade your netlab installation, execute pip3 install --upgrade networklab. New to netlab? Start with the Getting Started document and the installation guide. Need help? Open a discussion or an issue in netlab GitHub repository. ## Lab: Implementing VRF-Lite with VXLAN DevFeed: [Lab: Implementing VRF-Lite with VXLAN]() Original publisher: [Read original article]() Published: 2026-06-05T07:21:00Z Content type: tutorial Language: en Sources: [ipSpace.net blog]() Topics: [VXLAN](), [networking](), [IP routing](), [GitHub]() Tags: [apple](), [container](), [evpn](), [free](), [github](), [installation](), [ip-routing](), [netlab](), [protocol](), [routing](), [vxlan]() ### AI overview This lab exercise demonstrates how to implement a VRF-Lite design with VXLAN. The design uses VRF routing protocols over VXLAN-backed VLAN segments and requires IP routing on core switches instead of configuring VLANs and routing protocols for every VRF on every link and device. The lab can run on netlab-enabled infrastructure, a free GitHub Codespace, or an Apple-silicon Mac. ### Source excerpt Did you know that you can implement a VRF-Lite design with VXLAN? All you need are devices that can run VRF routing protocols over VXLAN-backed VLAN segments. Compared to the "traditional" VRF-Lite design, in which you need a set of VLANs on every link and every device running the routing protocol for every VRF, the VXLAN-based design needs just IP routing on the core switches, resulting in a design that's pretty close to what we were building with DMVPN (without IPsec and NHRP complications). Read more ... ## Using netlab to Argue with Vendor TAC DevFeed: [Using netlab to Argue with Vendor TAC]() Original publisher: [Read original article]() Published: 2026-06-04T05:42:00Z Content type: article Language: en Sources: [ipSpace.net blog]() Topics: [Network](), [bug](), [configuration](), [virtualization](), [Ubuntu]() Tags: [bug](), [configuration](), [data-center](), [installation](), [netlab](), [network](), [outage](), [ubuntu](), [virtualization]() ### AI overview A netlab user recreated a data center network topology with virtual network devices after a configuration change caused an outage. The lab reproduced the issue on vendor devices, allowing the user to send the topology file to the vendor TAC team for independent reproduction. The article also notes an installation problem involving libvirt, Ubuntu 25.04, and nested virtualization that was subsequently fixed. ### Source excerpt A happy netlab user sent me an unexpected use case: they successfully used its multi-vendor capabilities to argue with a vendor TAC. Here's the gist of the story (edited/anonymized for obvious reasons): They deployed a configuration change that resulted in an unexpected outage. The outage partially disrupted the data center network, so they didn't have the luxury of collecting data and reproducing the issue, as they had to roll back the change as expeditiously as possible. Read more ... ## EVPN Centralized Routing with Arista EOS DevFeed: [EVPN Centralized Routing with Arista EOS]() Original publisher: [Read original article]() Published: 2026-06-03T05:44:00Z Content type: tutorial Language: en Sources: [ipSpace.net blog]() Topics: [evpn](), [Routing (disambiguation)](), [networking](), [VXLAN]() Tags: [arp](), [cache](), [evpn](), [implementation](), [netlab](), [route](), [router](), [routing](), [vxlan]() ### AI overview This article examines which EVPN routes Arista EOS generates in a centralized routing design where a spine switch acts as the router and leaf switches operate at Layer 2. It explains that the central router does not advertise MAC+IP routes for hosts attached to its VLANs, routers must perform their own ARP resolution, and minimal configuration can cause routed traffic to be flooded. ### Source excerpt A month ago, I described ARP issues in EVPN centralized routing design, and Naveen Kumar Devaraj was kind enough to add some Arista EOS implementation details. Today, let's explore what EVPN routes Arista EOS generates in that scenario. We'll use a very simple lab topology with a spine switch acting as a router. The leaf switches are layer-2 switches. Packet forwarding in centralized routing design Read more ... ## SR-MPLS over Unnumbered Interfaces DevFeed: [SR-MPLS over Unnumbered Interfaces]() Original publisher: [Read original article]() Published: 2026-06-01T06:03:00Z Content type: tutorial Language: en Sources: [ipSpace.net blog]() Topics: [SR-MPLS](), [IS-IS](), [networking](), [Protocol (disambiguation)]() Tags: [container](), [demo](), [examples](), [github](), [implementation](), [installation](), [interfaces](), [ipv4](), [is-is](), [mpls](), [netlab](), [network](), [protocol](), [routing](), [sr-mpls](), [traffic-engineering]() ### AI overview This tutorial demonstrates SR-MPLS over unnumbered IPv4 point-to-point interfaces using netlab and IS-IS. It explains the resulting SR-MPLS and IS-IS advertisements, including adjacency and prefix segments, and provides steps for trying the lab through GitHub Codespaces and an Arista cEOS container. ### Source excerpt After the simple SR-MPLS demo and the dual-stack SR-MPLS setup, it was time for the next obvious question: Does SR-MPLS work over unnumbered IPv4 interfaces1, assuming the implementation of the underlying routing protocol supports them? Of course it does; let's go through the details, using the same topology I used throughout the Segment Routing workshop @ ITNOG10. Read more ... [Next page]()