nmcli and nmtui: Managing Connections from the CLI
Devices against connection profiles, the activation step everybody forgets, and how to make a configuration survive a reboot.
Go Deeper on Enterprise Networking
In-depth tutorials on OSPF, BGP, 802.1X, and more- for engineers who want to understand the why, not just the how.
OSPF
Open Shortest Path First, the link-state IGP behind most enterprise networks. Articles tagged OSPF cover neighbor relationships, LSA types, areas, DR/BDR election, and Cisco IOS XE configuration.
61 posts
BGP
Border Gateway Protocol, the path-vector protocol that holds the internet together and increasingly runs inside enterprise data centers. Articles tagged BGP cover fundamentals, neighbor states, path attributes, best-path selection, traffic engineering, and Cisco IOS XE configuration.
60 posts
802.1X
Port-based network access control, the standard for authenticating users and devices onto wired and wireless networks. Articles tagged 802.1X cover supplicant and authenticator behavior, RADIUS, EAP methods, Cisco ISE, dynamic VLANs, dACLs, host modes, and phased deployment.
38 posts
VLAN
Virtual LANs and Layer 2 switching, the foundation of every campus network. Articles tagged VLAN cover fundamentals, trunking, inter-VLAN routing, EtherChannel, troubleshooting, and campus design on Cisco Catalyst switches.
47 posts
Wireless
Enterprise Wi-Fi on Cisco Catalyst 9800, the WLC platform that replaced the AireOS generation. Articles tagged Wireless cover the configuration model, AP join, WPA3, FlexConnect, RRM, fast roaming, SSO HA, and IOS XE troubleshooting.
52 posts
STP
Spanning Tree Protocol, the loop-prevention mechanism that keeps Layer 2 networks stable. Articles tagged STP cover port roles and states, RSTP and MST, root bridge configuration, BPDU Guard and Root Guard hardening, and Cisco Catalyst troubleshooting.
36 posts
Latest posts
ethtool: Link Speed, Duplex, Offloads, NIC Stats
The driver layer below the kernel: link settings, offloads that make packet captures disagree with the wire, rings, and where host-side drops show up.
ifconfig, route, netstat: Legacy net-tools to iproute2
The full command map, and the same host through both toolsets so you can see exactly what the legacy tools hide from you.
ARP on Linux: ip neigh, arp, and Neighbor States
The six-state neighbor machine walked live on a real lab, the tunables behind it, and why arp -n cannot show you any of it.
ip route: Managing the Linux Routing Table
Every field in a route line, get against show, blackhole routes, the replace gotcha, and policy routing with multiple tables.
The Linux ip Command: The Complete Guide
The grammar, the four objects you use every day, the output modifiers that make it readable, and how to create interfaces out of nothing.
VXLAN EVPN Troubleshooting: What Actually Breaks
Four faults hit in a real Nexus fabric, the output that identified them, and an ordered method for the next one.
EVPN L3VNI and the Distributed Anycast Gateway
Symmetric IRB routes between VNIs on the leaf that receives the packet. Here is the L3VNI build and the real output that proves it worked.
A Real VXLAN Packet, Header by Header
A genuine VXLAN packet captured between a spine and a leaf, taken apart byte by byte from the outer MAC down to the ICMP echo request inside.
VXLAN L2VNI Configuration on Nexus, Proven
An L2VNI build on a real Nexus fabric, including the vPC anycast VTEP mistake that produced an empty peer table and how it was fixed.
BGP EVPN Route Types Explained with Real Output
EVPN route types stop being abstract the moment you read them off a real fabric. Here are Types 2, 3 and 5 from a working Nexus lab.
Ingress Replication vs PIM Anycast RP in VXLAN
BUM traffic still has to get everywhere in a VXLAN fabric. Here is how ingress replication handles it, and what you give up by not running PIM.