ipSpace.net

ipSpace.net

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Practitioner blog on networking.

Public Videos: Docker 101
NewsApr 10, 2026

Public Videos: Docker 101

ipSpace.net announced that its "Introduction to Docker" webinar, originally produced a few years ago, is now publicly available to anyone with an ipSpace.net account. The free video walks beginners through core Docker concepts such as images, containers, Dockerfiles, and basic...

By ipSpace.net
Worth Reading: Shameless Guesses, Not Hallucinations
NewsApr 7, 2026

Worth Reading: Shameless Guesses, Not Hallucinations

Scott Alexander argues that AI outputs are better described as "shameless guesses" or bullshit rather than hallucinations, because training rewards correct answers but does not penalize errors. He notes that saying "I don’t know" is discouraged for commercial reasons, turning...

By ipSpace.net
Lab: Summarizing IS-IS Level-1 Routes
NewsApr 3, 2026

Lab: Summarizing IS-IS Level-1 Routes

IS‑IS was originally built for NSAP addressing, separating node and area prefixes, but its IP implementation mirrors OSPF by defaulting to no automatic prefix summarization. Network operators must manually configure summarization to aggregate Level‑1 routes into the Level‑2 backbone. The...

By ipSpace.net
Every Layer of Review Makes You 10x Slower
NewsApr 1, 2026

Every Layer of Review Makes You 10x Slower

Avery Pennarun’s latest column reiterates that each additional review layer can slow work by roughly tenfold, emphasizing that technology—including AI—cannot compensate for fundamentally broken processes. The piece warns that AI evangelists often ignore this reality, promoting tools without addressing the...

By ipSpace.net
Lab: Anycast Gateways on VXLAN Segments
NewsMar 20, 2026

Lab: Anycast Gateways on VXLAN Segments

Anycast gateways, traditionally limited to VLAN segments, are now officially supported on VXLAN segments, extending a decade‑old Arista capability. The new lab exercise demonstrates how to configure dual anycast gateways across VXLAN underlay and overlay networks. It can be run...

By ipSpace.net
MANRS for Enterprise Customers
NewsMar 17, 2026

MANRS for Enterprise Customers

The MANRS initiative, aimed at securing Internet routing, has few participants in Croatia, Slovenia and Austria, leaving enterprises in those markets without verified ISP compliance. The author highlights the difficulty of locating MANRS‑certified providers and points to a new MANRS...

By ipSpace.net
Network Device Telemetry Protocols with Dinesh Dutt
NewsMar 13, 2026

Network Device Telemetry Protocols with Dinesh Dutt

In the latest episode of Software Gone Wild, the host discusses network device telemetry with Dinesh Dutt, a leading authority on the subject. The conversation examines why many operators still rely on screen‑scraping despite the availability of modern protocols such...

By ipSpace.net
IPv4 ECMP Works on Arista cEOS Release 4.35.2F
NewsMar 12, 2026

IPv4 ECMP Works on Arista cEOS Release 4.35.2F

Arista’s cEOS 4.35.2F release finally supports IPv4 ECMP, allowing forwarded traffic to be balanced across multiple equal‑cost paths in an anycast topology. The lab test shows packets alternating between two downstream nodes, confirming functional ECMP. However, locally originated traffic still...

By ipSpace.net
Netlab 26.03: EVPN/MPLS, IOS XR Features
NewsMar 10, 2026

Netlab 26.03: EVPN/MPLS, IOS XR Features

Netlab 26.03 has been released, bringing a suite of new multi‑vendor features to the network‑lab platform. Cisco IOS XR now supports SR‑MPLS, MPLS/VPN, EVPN over MPLS, VRRP, advanced BGP session parameters and extensive routing policies. Juniper cRPD, EVPN/VXLAN on vPTX and...

By ipSpace.net
Automating Netlab-Based Cisco SD-WAN Deployment
NewsMar 9, 2026

Automating Netlab-Based Cisco SD-WAN Deployment

Netlab, an open‑source lab generator, does not include native support for Cisco SD‑WAN. Sebastien d’Argoeuves created a GitHub repository that automates Cisco SD‑WAN deployment once a netlab lab is launched. The solution reads netlab’s JSON/YAML topology, maps device roles, and...

By ipSpace.net
Presentation: Netlab Overview and Use Cases
NewsMar 5, 2026

Presentation: Netlab Overview and Use Cases

At the recent NetBCN event, a concise presentation showcased netlab’s expanding portfolio of use cases, adding a dedicated “use cases” section to the standard deck. The speaker highlighted roughly a dozen scenarios, ranging from rapid prototyping of network designs to...

By ipSpace.net
Worth Reading: Faster than Dijkstra?
NewsMar 3, 2026

Worth Reading: Faster than Dijkstra?

Bruce Davie argues that using algorithms marketed as faster than Dijkstra’s in link‑state routing offers little practical benefit. Historical data shows Dijkstra can compute SPF for a 2,000‑node network in about 100 ms, comfortably meeting modern convergence needs. Most networks operate...

By ipSpace.net
Netlab: Using L3VPN (MPLS/VPN) with SR-MPLS Core
NewsMar 2, 2026

Netlab: Using L3VPN (MPLS/VPN) with SR-MPLS Core

The article demonstrates how netlab can orchestrate a full‑scale MPLS/VPN lab using an SR‑MPLS core, combining Arista cEOS PE routers with FRRouting P routers in Docker containers. LDP is disabled, forcing IS‑IS‑based segment routing to handle label distribution, while two...

By ipSpace.net
Lab: More Complex EVPN/VXLAN Bridging Scenario
NewsFeb 27, 2026

Lab: More Complex EVPN/VXLAN Bridging Scenario

The latest EVPN/VXLAN lab adds a more complex bridging scenario where several EVPN MAC‑VRFs are each mapped to separate VLAN segments on individual PE devices. The topology includes three routers interconnected via an IPv4 underlay running OSPF and iBGP, and...

By ipSpace.net
Configuring 6PE Route Reflector on Cisco IOS
NewsFeb 26, 2026

Configuring 6PE Route Reflector on Cisco IOS

Deploying a BGP route reflector for MPLS 6PE or L3VPN on Cisco IOS requires IPv6 routing to be enabled, even when the device never forwards IPv6 traffic. Without the "ipv6 unicast-routing" command, IOS rejects IPv6 address‑family configuration, causing integration tests to...

By ipSpace.net
On AI Agents Speaking BGP
NewsFeb 25, 2026

On AI Agents Speaking BGP

A recent proof‑of‑concept demonstrates an AI‑driven natural‑language interface that talks directly to a custom BGP daemon. The author argues that existing open‑source BGP suites like FRRouting already provide machine‑readable JSON and can be wrapped with simple REST APIs. Reinventing a...

By ipSpace.net
Interesting: Open Space Events
NewsFeb 24, 2026

Interesting: Open Space Events

Martin Fowler highlighted Open Space events as a self‑organizing format where participants set the agenda on the fly. The approach offers a structured yet flexible alternative to informal gatherings like Net::Beer, making it attractive for small tech meetups such as...

By ipSpace.net
Netlab: The Caveats of Using Startup Configurations
NewsFeb 23, 2026

Netlab: The Caveats of Using Startup Configurations

Petr Ankudinov warns against relying on containerlab's startup‑config option for netlab deployments. While containerlab can apply partial startup configurations to most devices, it only supports complete startup files for Arista cEOS, forcing netlab to duplicate initial device setup. Errors in...

By ipSpace.net
Public Videos: EVPN in MPLS-Based Environments
NewsFeb 20, 2026

Public Videos: EVPN in MPLS-Based Environments

The article announces that Krzysztof Szarkowicz’s presentation on EVPN in MPLS‑based environments is now publicly available as part of the EVPN Technical Deep Dive webinar series. While EVPN is often discussed alongside VXLAN, its original purpose was to serve as...

By ipSpace.net
Cisco IOS/XR OSPFv2 Not-So-Passive Interfaces
NewsFeb 19, 2026

Cisco IOS/XR OSPFv2 Not-So-Passive Interfaces

Cisco IOS/XR 25.2.1 violates the OSPF passive‑interface contract by still emitting OSPFv2 Hello packets. The router sends two hellos on a supposedly passive link, then stops, leaving the neighbor in the Init state and causing netlab integration tests to fail....

By ipSpace.net
EVPN IP-VRFs on Cisco IOS/XE: Configuration Notes
NewsFeb 18, 2026

EVPN IP-VRFs on Cisco IOS/XE: Configuration Notes

The author explains how to get EVPN IP‑VRFs with transit VXLAN working on Cisco IOS/XE, emphasizing the need to configure an explicit VLAN on switch images or a bridge‑domain on router images for the transit VNI. He outlines the required...

By ipSpace.net