N Is For Networking

Lenny Giuliano, Sr. Distinguished Systems Engineer at HPE Juniper Networks, joins Holly and Ethan for another round of multicast. Part two helps fill in details not covered in episode 50. They cover how multicast traffic also affects Ethernet frame addressing, and the key differences between IPv4 and IPv6 multicast. They also explain new hybrid multicast... Read more »

Today’s topic is Multiprotocol Label Switching or MPLS, a foundational technology that powers service provider networks and enterprise WANs all over the world. To help us break it down, we’ve invited James Bensley, a Network Tech Lead who’s spent fifteen years with MPLS. James explains what spurred the creation of MPLS and how it works... Read more »

Today’s learning adventure is an overview of multicast. Ethan and Holly have invited a guest to share his multicast expertise: Lenny Giuliano, Sr. Distinguished Systems Engineer at HPE Juniper Networks. Lenny guides them through multicast principles and shares examples of where and how it’s used in live networks. He also explains how the OSPF routing... Read more »

Today, Ethan and Holly provide an overview of firewalls. While cybersecurity is a separate discipline from network engineering, much of what happens in cybersecurity is interesting at the packet level, so there’s a good deal of overlap. It’s likely that as a network engineer, you’ll be managing, or at least dealing with, firewalls in your... Read more »

Quality of Service (QoS) is a huge topic with a punishingly large group of acronyms. Join Ethan and Holly as they help you build a mental framework of what QoS is and what it solves. Not only do they break down essential acronyms, they also discuss QoS fundamentals, define the major groups of QoS tools,... Read more »

Go beyond the basics to understand the mechanics that keep your default gateway from becoming a single point of failure. Ethan and Holly demystify Virtual Router Redundancy Protocol (VRRP), which helps provide network redundancy. They break down everything from the VRRP election protocol to the protocol’s unique communication methods. They also look back at previous... Read more »

Ethan and Holly discuss the major differences between In-band and Out-of-band (OOB) management and the pros and cons of both. They explore how to implement a proper OOB network and critical use cases where OOB is required. They also explain the differences and roles of the data plane, the control plane, and the management plane.... Read more »

If you’re curious as to what Ethan and Holly have in store for 2026, they give you a sneak peak on today’s episode. Hint: Some of these topics might include letters like B, G, P, Q, o, S, A and I. They also take time in this episode to answer listener questions, ranging from how... Read more »

In Part 1 of Redundancy vs. High Availability, we said that sometimes high availability and redundancy are considered to be the same thing, but we disagree. Holly and Ethan do agree that high availability can be considered a network design goal, and that redundancy is just one technique that can be used to help make... Read more »

In today’s chat, Holly and Ethan consider a question from listener Douglas who asks, “How do you approach designing a network for high availability and redundancy?” They start by defining differences between redundancy and high availability, and talk about Holly’s experience with her own customers. Then they share examples of how to achieve redundancy in... Read more »

MACsec is a protocol for encrypting Ethernet frames on a local (though not always local) network. Ethan Banks and Holly Metlitzky have an ELI5 (explain like I’m 5) discussion as to what exactly is MACsec and how it differs from IPsec. They talk about when and whether you need to implement MACsec with all the... Read more »

If you’ve ever wondered what the difference is between a Switched Virtual Interface (SVI) and Integrated Routing and Bridging (IRB), today’s show is for you! Ethan Banks and Holly Metlitzky start with some history and the basics of communication between layer 2 and layer 3 and then explain how the concepts of SVI and IRB... Read more »

The job interview is an inescapable part of a career journey. Today on N Is For Networking, we conduct a mock interview with a candidate who’s applying for a junior network administration role. The goal is to give Toni Mrowetz, our candidate, feedback. At the same time, we hope this helps anyone listening who might... Read more »

We dive back into the world of IPsec with an episode dedicated to configuring IPsec tunnels. After discussing a listener comment regarding transport mode in IPsec tunnels, Ethan Banks and Holly Metlitzky work through topics such as multi-vendor IPsec configuration, licensing, and the details of configuration and routing. Bonus material: MTU size and NAT-T. Episode... Read more »

We got some interesting listener feedback from our series on OSPF, so today’s N Is for Networking is another “Well actually” episode where we dig into that feedback. In particular, we’ll cover a defense of OSPF multi-area deployments, and dig into OSPF LSA types. Episode Links: OSPF Basics – N Is For Networking Episode 38... Read more »

It’s time to talk crypto. No, not the Bitcoin kind. Ethan and Holly introduce the basics of IPsec, the protocol that authenticates and encrypts traffic between endpoints. They discuss what it is, how it provides trustworthiness and secrecy to IP traffic, and common use cases. They review the different types of IPsec protocols and modes,... Read more »

Ethan and Holly bring you the last installment of the OSPF series discussing OSPF area types. They discuss why OSPF areas exist, do a quick recap of what OSPF areas actually are, and then introduce the different types of OSPF areas. Lastly, see if you can answer Ethan’s rapid-fire OSPF questions. Episode Transcript: This episode... Read more »

We ask listeners for follow up and you’ve sent it in. On today’s show we respond to listener comments and corrections on tunneling, the link aggregation control protocol, link aggregation in general, and DHCP options. We also talk about the network engineering certification journey. If you’ve got a “Well, actually” or any other follow up,... Read more »

Ethan and Holly continue their OSPF journey this week with OSPF Network Types. They discuss the two main OSPF network types used today: the broadcast and point to point networks. They also explain designated routers, backup designated routers, and when those are used and why. Lastly they discuss some soft skills – knowing your vendor... Read more »

Our OSPF series continues with a look at OSPF neighbor formation and related timers. We talk about the five major packet types that carry information among OSPF routers, how OSPF routers become neighbors, how they negotiate link-state database exchanges, keep-alive messages, and how they negotiate designated and backup routers when multiple devices are on the... Read more »

By popular request (and now that we have some other background topics covered) we start our series on the Open Shortest Path First (OSPF) routing protocol. We kick off the series with OSPF basics including Link State Advertisements, Link State Database, and other related essentials. We’ll explore additional OSPF topics over subsequent episodes. This week’s... Read more »

If you need to route in your network, you can program static routes into all your routing-capable devices. And this can work. But at some point, you’re probably going to want to switch to a dynamic routing protocol. On today’s N Is For Networking, Ethan and Holly discuss the differences between static and dynamic routes,... Read more »

What shape is your network? In other words, what is its topology? On today’s episode, we discover the different types of network topologies and designs used in the enterprise, data center, and service provider networks. We cover leaf/spine, hub and spoke, point to point, mesh, and others. We also talk about how topologies affect traffic... Read more »

Let’s explore four goals of network design: stability, speed, scalability, and security. These goals are based on Ethan’s experience designing, building, and operating networks. Network architects and design experts might have other objectives, and that’s fine, but these four goals are the basis of today’s episode. Ethan and Holly discuss why these four goals are... Read more »

We wanted to do an episode on SD-WAN, but realized we needed to set the stage for how wide-area networking developed. That’s why today’s episode is a history lesson of the Wide Area Network (WAN). We talk about how WANs emerged, public and private WANs, how WANs connect to LANs and data centers, the care... Read more »

On today’s show, we’re going to dig deeper into tunnels and explore some of the quirks and features of tunnels. This week we’ll discuss maximum transmission units (MTUs), maximum segment size, IP fragmentation and more. Today’s bonus material is more RFCs – RFC 4821 and RFC 8899. Episode Links: What Is a Tunnel? – N... Read more »

Let’s dig into tunnels. While some network engineers may want to quibble, a tunnel is when you put one packet inside of another packet to carry it across a network (frames also come into the picture, so hold off on your follow-ups for now). On today’s N Is For Networking, Ethan and Holly explore this... Read more »

The Dynamic Host Configuration Protocol (DHCP) assigns an IP address to a host that joins a network, along with other information necessary for the host to communicate. DHCP also has more to it, so this week’s episode is meant to be a solid introduction to this essential network protocol. We first discuss what it is... Read more »

This week we continue with DNS. In our last episode we covered the basics; today we expand our scope to cover topics such as security for DNS, reverse DNS, and DNS record types. For dessert this week, a serving of Raspberry Pi and Happy Eyeballs. Episode Links: DNS: Turning Names into Numbers – N Is... Read more »

The Domain Name System (DNS) keeps the Internet running. On today’s N Is For Networking podcast, we talk about how DNS transforms human-readable host names into IP addresses so that Internet traffic can be sent to the right place. We talk about root name servers, Top Level Domains (TLDs), and other elements of the DNS... Read more »

Following last week’s introduction to network monitoring, we discuss the Simple Network Management Protocol (SNMP), one of the most implemented types of network monitoring. We discuss how it is organized, operations that SNMP can perform, and versions of SNMP. This week’s bonus conversation is a discussion on the future for SNMP. Episode Links: MIB tree... Read more »

How do you know what is happening within your network, especially when something isn’t working? Network monitoring is the answer. On today’s show, we’ll start with the basics of network monitoring. We’ll cover what it is, how it’s used, and suggest some paid and open source network monitoring tools. This week’s bonus material is a... Read more »

To cert or not to cert? That is the question Holly & Ethan discuss on today’s episode. Will a certification really land you a networking job? Are certs the guaranteed path to tech career success? We consider this, talking through the benefits, challenges and even risks of networking industry certification. And there’s some bonus material,... Read more »

In today’s episode, we continue the discussion about routing and routing protocols by focusing on commonalities rather than differences among protocols such as OSPF, RIP, EIGRP, or BGP. We explain how, in general, routing protocols discover each other, communicate, maintain relationships, and exchange routing information. Next, we explore the topics of selecting best paths in... Read more »

Ready for more routing and routing protocols? Today we discuss the roles of the network operating system (NOS), routing protocols, the Routing Information Base (RIB), and the Forwarding Information Base (FIB). We also include the dynamics of routing protocols, the importance of hardware like TCAM for performance, and the concept of administrative distance or route... Read more »

On today’s N Is For Networking, we explore the fundamentals of routing, focusing on layer 3 of the OSI model. We explain the concepts of routers, routing tables, and routing protocols, and discuss why it’s important to have a firm grasp of these concepts before you tackle advanced topics such as VXLAN and EVPN. Today’s... Read more »

The line between switches and routers can get a little blurry. On today’s N Is For Networking, we try to clear things up. We start by defining what a router and switch are, and then provide some historical and technical context to better understand the differences. Then we discuss how modern switches have evolved to... Read more »

We’re back with the third and last (for now) installment of our spanning tree series. Today’s episode includes an explanation of spanning tree versions, 802.1D, 802.1w, 802.1s, and their practical implications for network design. The discussion then turns to BPDU guard for preventing loops and ensuring rapid connectivity. Bonus material on why you should or... Read more »

Welcome to part 2 of our spanning tree series. We start with a quick review and then discuss root bridges, root ports, designated ports, and forwarding and blocked ports. We explain the impact of topology changes on spanning tree and network performance, and discuss how topology changes and convergence events are communicated. Last but not... Read more »

Spanning tree is a topic so mysterious and complicated that common advice is just to disable it. In today’s episode, we start a mini-series on spanning tree, hoping to better explain what it is and what it does. We begin with basic spanning tree terminology and its role in preventing loops in an Ethernet network.... Read more »

Why do we need network models such as OSI? Network architect and author Russ White joins Holly and Ethan to talk about how network models can help engineers ask intelligent questions and understand networking problems. And OSI isn’t your only option–Russ digs into the RINA model and how it compares to OSI (which we covered... Read more »

In today’s episode, we address listener Kieren’s question about the differences between LAG, MLAG, MC-LAG, and stacking. We tackle the nuances of Link Aggregation (LAG) and the Link Aggregation Control Protocol (LACP), and explain their roles in redundancy and bandwidth efficiency. We also discuss the complexities and differences among vendors and overall benefits of Multi-Chassis... Read more »

It’s history day on N Is For Networking! We learn about the development of IPv6 directly from Bob Hinden, one of the pioneers who made it happen. Bob discusses his journey from early work on ARPANET to his significant contributions to IPv6. We also cover the transition from IPv4, the challenges faced during IPv6’s creation,... Read more »

On today’s episode, we’re explaining high-speed Ethernet lanes at the request of listener Matthew. We cover lanes, channels, and their physical representation in networking – think actual cables. We explain both 40Gb and 100Gb technologies and compare them to Link Aggregation Control Protocol (LACP). We also have a discussion on standards and practical implications for... Read more »

Today’s topic is the default gateway, essential for routing traffic between networks. We explain its purpose, configuration, and the consequences of incorrect settings. Using home networks as an example, Ethan and Holly illustrate how default gateways enable devices to communicate with external networks. The discussion also covers routing tables, subnet masks, and the differences between... Read more »