--- title: "Technical note on IP fabrics published" source: "https://www.tigera.io/blog/technical-note-on-ip-fabrics-published/" --- [Technical Blog](https://www.tigera.io/category/technical-blog/) # Technical note on IP fabrics published By [Christopher Liljenstolpe](https://www.tigera.io/blog/author/chris-liljenstolpe/) on Mar 31, 2015 • 2 min read A while (too long) ago, I promised that I would follow up on my discussion about [Ethernet fabrics](http://docs.projectcalico.org/en/latest/l2-interconnectFabric.html) with a similar discussion on using IP fabrics to interconnect Calico nodes.  That work is (finally) done, and can be found in our [technical documentation](http://docs.projectcalico.org/) entitled, *[IP Interconnect Fabrics in Calico](http://docs.projectcalico.org/en/latest/l3-interconnectFabric.html).* For those of you who will *eventually* get around to reading it, but want the spoiler right now, we conclude that IP interconnect fabrics (*i.e.*running a top of rack switch as a router) is feasible in Project Calico.  There are more considerations than in the Ethernet case, discussed in the *[Calico Over an Ethernet Inteconnect Fabric](http://docs.projectcalico.org/en/latest/l2-interconnectFabric.html)*note, some of which include: - Size of the routing table in the Calico network and compared to the forwarding table size in the switches being used - Insuring proper autonomous system boundaries and insuring continuity of those autonomous systems - Insuring correct next–hop behavior in the routing announcements We propose two viable BGP models for a Calico IP interconnect fabric: - An AS per rack model - An AS per server model Each of these models can have two variants, depending on whether the spine switches are also BGP routers, or separate Ethernet planes as in the Ethernet fabric option. Please read the note, and comment, make suggestions, rant & rave, or congratulate our intelligence. [Open Source](https://www.tigera.io/tags/open-source/)[Project Calico](https://www.tigera.io/tags/project-calico/) ## Related posts [![What’s new in Calico: Spring 2026 Release](https://www.tigera.io/app/uploads/2026/06/Whats-New-in-Calico-NEW-TEMPLATE-2026.png)](https://www.tigera.io/blog/whats-new-in-calico-spring-2026-release/) [Company Blog](https://www.tigera.io/category/company-blog/) #### [What’s new in Calico: Spring 2026 Release](https://www.tigera.io/blog/whats-new-in-calico-spring-2026-release/) By [Veronika Smolik](https://www.tigera.io/blog/author/veronika-smolik/) on Jun 2, 2026 Kubernetes has come a long way since its debut in 2014. It’s gone from running a couple of containerized microservices to orchestrating fleets of production workloads spanning everything from AI agents to full scale VMs... [Read more](https://www.tigera.io/blog/whats-new-in-calico-spring-2026-release/) [![Kubernetes Operational Maturity: Secure and Resilient Cluster Federation with Cluster Mesh](https://www.tigera.io/app/uploads/2026/05/Kubernetes-Operational-Maturity-Secure-and-Resilient-Cluster-Federation-with-Cluster-Mesh.png)](https://www.tigera.io/blog/kubernetes-operational-maturity-secure-and-resilient-cluster-federation-with-cluster-mesh/) #### [Kubernetes Operational Maturity: Secure and Resilient Cluster Federation with Cluster Mesh](https://www.tigera.io/blog/kubernetes-operational-maturity-secure-and-resilient-cluster-federation-with-cluster-mesh/) By [Veronika Smolik](https://www.tigera.io/blog/author/veronika-smolik/) on May 25, 2026 Practically no one runs a single Kubernetes cluster in production these days. Maybe that’s how it started but data sovereignty requirements, acquisitions, AI initiatives and the need for edge servers, among other considerations, have pulled... [Read more](https://www.tigera.io/blog/kubernetes-operational-maturity-secure-and-resilient-cluster-federation-with-cluster-mesh/) [![What’s New in Calico v3.32](https://www.tigera.io/app/uploads/2026/05/Green-Please-use-a-different-background-color-alternately-1.png)](https://www.tigera.io/blog/whats-new-in-calico-v3-32/) #### [What’s New in Calico v3.32](https://www.tigera.io/blog/whats-new-in-calico-v3-32/) By [Reza Ramezanpour](https://www.tigera.io/blog/author/rezar/) on May 13, 2026 We’re excited to announce the release of Calico Open Source v3.32! 🎉 This release corresponds with Kubernetes v1.36 (Codename Haru) and it goes beyond just sharing a cat as the mascot of the release, it... [Read more](https://www.tigera.io/blog/whats-new-in-calico-v3-32/)