Packets DownRange
Interconnection, peering, Data centers. How the Internet works. IXPs, transit, and other topics. Routing and Control Planes such as BGP and OSPF protocols. RPKI and IP resources are also covered.
I, due to recent SSH vulnerabilities in MikroTik, figured this series of articles would be relevant. The router may have strong passwords and firewall filters, but those services still receive constant login attempts from automated scanners. For years, the normal answer was a VPN with a management network. VPNs work well, but they require another … Read more
Let’s look at another BGP attribute, the Multi-Exit Discriminator, or MED. Two networks may interconnect in more than one location, and MED lets you attach a preference to the routes you advertise. An ISP might connect to the same upstream in Indianapolis and Chicago while advertising the same prefixes at both locations. The upstream now … Read more
Have you ever looked at a data center marketing slick and wondered what N, N+1, 2N, and 2(N+1) actually mean? The main thing they tell you is how many components can fail before the system drops below the capacity needed to support the load. When I evaluate a data center, I want to know what … Read more
Multi-core fiber places several independent optical cores inside one standard 125-micron cladding. It increases channel density, but it also requires different connectors, splicing methods, and testing procedures.
Prefix lists define which BGP routes match a policy. Route maps use those matches to permit routes, deny them, or change attributes such as local preference.
5 minute read time.Justin Wilson j2sw.com When you configure a BGP session, one of the first questions is what routes you actually want to receive. If you have ever filled out a questionnaire with Hurricane Electric or another transit provider, they ask you what “kind” of routes you want. In this article, I plan to … Read more
If you’ve spent any time looking into fiber Internet, you’ve probably run across terms like GPON, XGS-PON, OLT, and ONT. These are all parts of what’s called a Passive Optical Network, or PON. Most residential fiber providers use PON because it lets them connect alot of homes without having to pull a separate fiber from … Read more
We are starting to hear about “Thin” and “Fat” rails in AI fabrics. These are just another way to say a connection from compute into the Fabric. The link either has sufficient capacity (Fat) or insufficient capacity (Thin). A thin rail provides the node with a single path into the fabric. That may be one … Read more
I originally posted this over on the FD-IX Bloghttps://blog.fd-ix.com/george-washington-the-delaware-and-direct-routes/ When George Washington crossed the Delaware River on Christmas night in 1776, the goal was simple. Reach the objective by the most effective path while avoiding unnecessary delays and giving the opposing force as little warning as possible. The crossing was risky, but it created a … Read more
A browser does not always need the whole file at once. Sometimes it only needs a slice of the file. That slice might be the next part of a video or a chunk of a large object sitting behind a CDN. When that happens, the client can request a byte range instead of requesting the … Read more
Justin Wilson announces his second children’s networking book, A Kid’s First Visit to an Internet Exchange. Follow Sam as he learns how networks meet, peer, and move Internet traffic.
A data center fabric connects servers, storage, and network devices using a leaf-spine architecture designed for high bandwidth and predictable latency. Learn how packets move through a fabric, why ECMP matters, and how modern data centers support virtualization, cloud, and AI workloads.