Upcoming BGP Labs, 2024 Edition
It’s that time of the year when we create unreachable goals and make empty promises to ourselves (or others) that we subconsciously know we’ll fail.
I tried to make that process a bit more structured and create external storage for my lab ideas – I started publishing more details on future BGP lab scenarios. The lab descriptions contain a high-level overview of the challenge and the lab topology; the details will be filled in later.
Want to know what’s coming in 2024? Check out the Upcoming Labs page of the BGP Labs project.
A While, Career update and Ends with various Junos load commands.
It has been quite some time since my last blog post. The past few months have been busy, leaving little time to write. I am happy to share that I have started working as a site-reliability developer at Oracle. While it has only been a short while, I am enjoying the work.
Reflecting on the past year, I am happy to say it has been productive overall. I have had the opportunity to collaborate with various networking and software teams, which has taught me a lot about high-scale traffic patterns and migrations. Working in an operations role has been beneficial since it requires constant fire-fighting and documentation for improvements. This has made me more aware of traffic patterns and ways to improve reliability.
What can be improved?
However, I could benefit from more study on the software architecture and distributed system design parameters from a business perspective. I want to write more this year; the first half was better, but lacked in the second half, where most of the writing was private.
From a personal standpoint, 2024 needs more travel absolutely and some improvements in garden automation for summer 2024
Other updates
Finally, I have been working on some JNCIA-Devops Continue reading
About password security and credential stuffing
Common Falsehoods About Password Security and Credential Stuffing
TechCrunch published an article that gives class-action lawyers suing 23andMe a mouthpiece to editorialize about password security practices, masquerading as a news article. The upshot of the ~article~ editorial is this:
- A large number of 23andMe’s customers were subject to a credential stuffing attack.
- Design choices in 23andMe’s site allowed other customer data to be exposed via accounts compromised in the credential stuffing attack.
- 23andMe’s mitigations for credential stuffing attacks were inadequate.
- 23andMe should be held liable for this.
I want to focus here on the third point: credential stuffing attack mitigations. I’ve worked quite a bit on analyzing large credential stuffing attacks and recommending mitigations for them. I also served as a technical escalation point for customers who had a wide variety of strongly held false beliefs about password security credential stuffing mitigation. In reading various social media responses the 23andMe case, I see all these false beliefs turning up again. Let’s have a look at some.
False: Rate limiting login attempts is a great mitigation
The first question we need to answer here is: what do you mean by rate limiting? Usually there are two main rate limits that people Continue reading
Meshtastic quick setup
I wanted some nice offline mid range chat app, for when I don’t have data, or data roaming is too expensive. I also want it to work for people who are not amateur radio licensed, since my girlfriend stubbornly refuses to be interested in that.
Looks like the answer I’m looking for is Meshtastic, preferably with LoRalora]. I bought a couple of Heltec V3 ESP32 LoRa OLED and the matching case.
Maybe I’ll buy a battery, but I’m fine just powering it from a USB power bank.
The documentation makes a fair bit of assumptions about the user knowing the name for what they want, and what firmware provides what.
In short, what I think I want is to ignore the Heltec firmware, and instead just treat the Heltec V3 as the hardware that Meshtastic runs on.
The recommended way to flash, and for some cases even use, is the Meshtastic Web UI. It uses browser integration for serial ports and bluetooth. A nice idea, but it was extremely unreliable for me. The flasher worked for one device, but not the other. The chat client never worked at all.
Here’s what worked reliably for me:
- Download “stable” firmware Continue reading
Wi-Fi, Cellular, or Ethernet? (Or All Three?)
How multi-access NaaS frees IT to match each use case to the right network and simplifies decision-making, management, and cost control.A Look into the State of MLB Connectivity with Extreme Networks and San Francisco Giants
Wi-Fi networks in MLB stadiums provide connectivity for fans, concession stands, security, video distribution, broadcasters, roving cameras, iPads for coaches, and much more.BGP EVPN Part II: Network Virtualization Overlay with BGP EVPN and VXLAN – Introduction
In Figure 1-1, we have a routed 3-stage Clos Fabric, where all Inter-Switch links are routed point-to-point layer-3 connections. As explained in previous sections, a switched layer-2 network with an STP control plane allows only one active path per VLAN/Instance and VLAN-based traffic load sharing. Due to the Equal Cost Multi-Path (ECMP) supported by routing protocols, a routed Clos Fabric enables flow-based traffic load balancing using all links from the ingress leaf via the spine layer down to the egress leaf. The convergence time for routing protocols is faster and less disruptive than STP topology change. Besides, a routed Clos Fabric architecture allows horizontal bandwidth scaling. We can increase the overall bandwidth capacity between switches, by adding a new spine switch. Dynamic routing protocols allow standalone and virtualized devices lossless In-Service Software Update (ISSU) by advertising infinite metrics or withdrawing all advertised routes.
But how do we stretch layer-2 segments over layer-3 infrastructure in a Multipoint-to-Multipoint manner, allowing tenant isolation and routing between segments? The answer relies on the Network Virtualization Overlay (NVO3) framework.
BGP EVPN, as an NVO3 control plane protocol, uses EVPN Route Types (RT) in update messages for identifying the type of advertised EVPN NLRIs (Network Continue reading
Public Cloud Networking Hands-On Exercises
I got this request from someone who just missed the opportunity to buy the ipSpace.net subscription (or so he claims) earlier today
I am inspired to learn AWS advanced networking concepts and came across your website and webinar resources. But I cannot access it.
That is not exactly true. I wrote more than 4000 blog posts in the past, and some of them dealt with public cloud networking. There are also the free videos, some of them addressing public cloud networking.
Public Cloud Networking Hands-On Exercises
I got this request from someone who just missed the opportunity to buy the ipSpace.net subscription (or so he claims) earlier today
I am inspired to learn AWS advanced networking concepts and came across your website and webinar resources. But I cannot access it.
That is not exactly true. I wrote more than 4000 blog posts in the past, and some of them dealt with public cloud networking. There are also the free videos, some of them addressing public cloud networking.
EVPN Deepdive Route Types 2 and 3
In my last post on Configuring EVPN, we setup EVPN but configured no services. In this post we will configure a basic L2 service so we can dive into the different EVPN route types. This post will cover route type 2 and 3 together as you will commonly see these together. This post will cover:
- Discovery of VTEPs.
- How to map a VLAN to a VNI.
- Automatic generation of RD and RT.
- Advertising MAC- and optionally IP address (route type 2).
- Ingress replication with dynamic discovery of VTEPs (route type 3).
The topology we will use for this post is shown below:
Before diving into configuration, let’s discuss something that is often overlooked, VTEP discovery.
VTEP discovery
Without EVPN, VXLAN uses flood and learn behavior for discovery of VTEPs. This means that any host sending VXLAN frames would be considered a trusted VTEP in the network. This is obviously not great from a security perspective. When using EVPN, adding VTEPs is based on BGP messages. A VTEP will learn about other VTEPs based on these BGP updates. It’s not a specific route type, but rather any type of EVPN message. This makes it more difficult to add a rogue Continue reading
Protecting Against MAC Flooding Attack
In the "MAC Flooding Attack" tutorial, we explained how to easily saturate the MAC address […]
The post Protecting Against MAC Flooding Attack first appeared on Brezular's Blog.
A Look Back at 2023: A Year of Something Something Networking
Based on happenings last year, it's a good time to be in the networking space. We're on the cusp of seeing a lot of innovation and exciting new capabilities become part of both multi-cloud and microservices networking.Modern Network Troubleshooting
I’ve reformatted and rebuilt my network troubleshooting live training for 2023, and am teaching it on the 26th of January (in three weeks). You can register at Safari Books Online. From the site:
The first way to troubleshoot faster is to not troubleshoot at all, or to build resilient networks. The first section of this class considers the nature of resilience, and how design tradeoffs result in different levels of resilience. The class then moves into a theoretical understanding of failures, how network resilience is measured, and how the Mean Time to Repair (MTTR) relates to human and machine-driven factors. One of these factors is the unintended consequences arising from abstractions, covered in the next section of the class.
The class then moves into troubleshooting proper, examining the half-split formal troubleshooting method and how it can be combined with more intuitive methods. This section also examines how network models can be used to guide the troubleshooting process. The class then covers two examples of troubleshooting reachability problems in a small network, and considers using ChaptGPT and other LLMs in the troubleshooting process. A third, more complex example is then covered in a data center fabric.
A short section on proving Continue reading
VRF Without Route Target – Will the Route Be Exported?
Yesterday I posted a tricky question to Twitter. If you have a working VPNv4 environment and create a VRF with only a Route Distinguisher (RD) but without Route Targets (RT), will the route be exported? The answer may surprise you! The configuration supplied in the question was similar to the one below:
vrf definition QUIZ rd 198.51.100.1:100 ! address-family ipv4 exit-address-family ! interface GigabitEthernet2 vrf forwarding QUIZ ip address 203.0.113.1 255.255.255.0 ! router bgp 65000 ! address-family ipv4 vrf QUIZ network 203.0.113.0
Notice how this VRF has a RD but no RT. Will this router, PE1, advertise the route into VPNv4? Most would say no, but the answer is yes. Let’s first check that we see the route locally on PE1 in VRF QUIZ:
PE1#show bgp vpnv4 uni vrf QUIZ 203.0.113.0
BGP routing table entry for 198.51.100.1:100:203.0.113.0/24, version 4
Paths: (1 available, best #1, table QUIZ)
Advertised to update-groups:
1
Refresh Epoch 1
Local
0.0.0.0 (via vrf QUIZ) from 0.0.0.0 (198.51.100.1)
Origin IGP, metric 0, localpref 100, weight 32768, valid, sourced, local, best
mpls Continue reading
Back On Track in 2024
It’s time to look back at my year that was and figure out where this little train jumped off the rails. I’ll be the first to admit that I ran out of steam chugging along toward the end of the year. My writing output was way down for reasons I still can’t quite figure out. Everything has felt like a much bigger task to accomplish throughout the year. To that end, let’s look at what I wanted to do and how it came out:
- Keeping Track of Things: I did a little bit better with this one, aside from my post schedule. I tried to track things much more and understand deadlines and such. I didn’t always succeed like I wanted to but at least I made the effort.
- Creating Evergreen Content: This one was probably a miss. I didn’t create nearly as much content this year as I have in years past. What little I did create sometimes felt unfocused and less impactful. Part of that has to do with the overall move away from written content to something more video and audio focused. However, even my other content like Tomversations was significantly reduced this year. I will Continue reading
Expect a BEAD Broadband Slowdown in 2024
Enterprises are advised to monitor broadband deployment activity at the state level as providers take advantage of funding made available in the Broadband Equity Access and Deployment (BEAD) portion of the nation's Infrastructure and Jobs Act.BGP EVPN Part-I: Challenges in Traditional Switched Datacenter Networks
Inefficient Link Utilization
The default Layer 2 Control Plane protocol in Cisco NX-OS is a Rapid Per-VLAN Spanning Tree Plus (Rapid PVST+), which runs 802.1w standard Rapid Spanning Tree Protocol (RSTP) instance per VLAN. Rapid PVST+ builds a VLAN-specific, loop-free Layer 2 data path from the STP root switch to all non-root switches. Spanning Tree Protocol, no matter which mode we use, allows only one active path at a time and blocks all redundant links. One general solution for activating all Inter-switch links is placing an STP root switch for odd and even VLANs into different switches. However, STP allows only a VLAN-based traffic load balancing.
CPU and Memory Usage
After building a loop-free data path, switches running Rapid PVST+ monitor the state of the network by using Spanning Tree instance-based Bridge Protocol Data Units (BPDU). By default, each switch sends instance-based BPDU messages from their designated port in two-second intervals. If we have 2000 VLANs, all switches must process 2000 BPDUs. To reduce CPU and Memory consumption caused by BPDU processing, we can use Multiple Spanning Tree – MSTP (802.1s), where VLANs are associated with Instances. For example, we can attach VLANs 1-999 to one instance and Continue reading
Goodbye, ipSpace.net Subscription
I ran the first webinar as an independent author almost exactly fourteen years ago1, with the first ticket sold just before New Year’s Eve. I kept focusing on individual webinars until someone asked me, “Would it be possible to buy access to everything you did?” His question effectively created the ipSpace.net subscription, with the first one sold in late 2010 (I still have the email that triggered the whole process).
Goodbye, ipSpace.net Subscription
I ran the first webinar as an independent author almost exactly fourteen years ago1, with the first ticket sold just before New Year’s Eve. I kept focusing on individual webinars until someone asked me, “Would it be possible to buy access to everything you did?” His question effectively created the ipSpace.net subscription, with the first one sold in late 2010 (I still have the email that triggered the whole process).
Apollo 11 notes
I was re-reading the Apollo 11 mission reports, as one does, and decided to take some notes along the way.
If you’re interested in these things, I also highly recommend curiousmarc’s series on the Apollo comms hardware.
Notes
First time I’ve seen the word “doff”. Can’t wait to use it in daily conversation.
The rocket equation is a beast. The LM descent stage had 8’210kg of
propellant. The ascent stage only 2’365kg.
– Volume 1, Page 50
In total 10’849kg out of 15’061 (72%) of the LM was
propellant. (excluding the astronauts themselves)
The LM flown on Apollo 10 did not have the landing program in its computer.
To prevent the temptation to land?
– Volume 1, Page 62
Armstrong’s parents were “Mr. and Mrs. Stephen Armstrong”. Michael Collins’ mother is mentioned, but her name is also lost to history, as she’s referred to as “Mrs. James L. Collins”. Only Buzz Aldrin’s mother is named (and what a name!), as Marion Moon Aldrin.
All three were born in 1930, making them turn 39 in 1969.
– Volume 1, Page 76-78
“High speed” data mode is 2400bps, divided into 240 bit blocks.
– Volume 1, Page 93
Aside from the Continue reading