Managing Multiple Python Versions with pyenv

Managing Multiple Python Versions with pyenv

In my Python journey, I've always stuck to just one version of Python at a time. I happily used Python 3.9 for quite a while, then switched to Python 3.10 without any issues. Everything was perfect until recently when I tried installing a Python application using pip, but no matter what I did, the installation kept failing. I couldn't fix the issue even after hours of Googling.

That's when I finally decided to check the documentation (which I should have done from the start), and there it was, this application requires a minimum Python version of 3.8 and was only tested on versions 3.8 and 3.9. That made me think, maybe I should have installed it using Python 3.9, but how? I'm no expert in Linux or Unix systems, and I worried that reinstalling Python 3.9 could mess up other projects I'd built on 3.10.

So, I started exploring how to manage multiple Python versions on the same machine, and that's when I stumbled upon a tool called 'pyenv'. This seemed like the perfect solution to my problem, so I decided to learn more about it.

Python For Network Engineers Continue reading

Cisco vPC in VXLAN/EVPN Network – Part 2 – Configuring vPC

When building leaf and spine networks, leafs connect to spines, but leafs don’t connect to leafs, and spines don’t connect to spines. There are exceptions to this and vPC is one of those exceptions. The leafs that are going to be part of the same vPC need to connect to each other. There are two ways of achieving this:

  • Physical interfaces.
  • Fabric peering.

We will first use physical interfaces and then later remove that and use fabric peering. Now, my lab is virtual so take physical with a grain of salt, but they will be dedicated interfaces. The following will be required to configure vPC:

  • Enable vPC.
  • Enable LACP.
  • Create vPC domain.
  • Create a VRF for the vPC peer keepalive.
  • Configure the interface for vPC peer keepalive.
  • Configure the vPC peer keepalive.
  • Configure the vPC peer link interfaces.
  • Configure the vPC peer link.

This is shown below:

The vPC is now up:

Leaf1# show vpc
Legend:
                (*) - local vPC is down, forwarding via vPC peer-link

vPC domain id                     : 1   
Peer status                       : peer adjacency formed ok      
vPC keep-alive status             : peer is alive                 
Configuration consistency status  : success 
Per-vlan consistency status       : success                       
Type-2 consistency status         : success 
 Continue reading

Repost: The Real LISP Mobility Use Case

Béla Várkonyi is working on an interesting challenge: building ground-to-airplane(s) networks providing multilink mobility. Due to its relative simplicity, he claims LISP works much better than BGP in that environment.

In some newer routers BGP would not be such a big bottleneck, but you need a lot of knob turning in BGP to get it right, while in LISP it is quite simple.

If you have many thousands concurrent airplanes with multi-link and max. 16 subnets with different routing policies on each, and the radio links are going up and down, then you have a large number of mobility events.

Read more …

Repost: The Real LISP Mobility Use Case

Béla Várkonyi is working on an interesting challenge: building ground-to-airplane(s) networks providing multilink mobility. Due to its relative simplicity, he claims LISP works much better than BGP in that environment.

In some newer routers BGP would not be such a big bottleneck, but you need a lot of knob turning in BGP to get it right, while in LISP it is quite simple.

If you have many thousands concurrent airplanes with multi-link and max. 16 subnets with different routing policies on each, and the radio links are going up and down, then you have a large number of mobility events.

Read more …

History of Networking: Updated Links

Someone told me some (or many?) of the links are broken to the History of Networking recordings. I went through the S3 bucket and renamed all the files so there are no spaces (because S3 buckets don’t always work right with spaces), and then checked them all to make certain they work. Along the way I found three or four episodes that were recorded and not on the HoN page, so I added them.

Check out the corrected listing here.

I think I have one more recording that was never edited and published; I will probably put it in the Hedge stream in the next month or two just so it’s out there.

Tech Bytes: Using ZTNA for VPN Consolidation, Protecting Dev Access with SSE (Sponsored)

Zero Trust Network Access, or ZTNA, is a core element of a Security Service Edge because it enables secure remote access to on-prem and cloud-based applications. On today’s episode, sponsored by HPE Aruba Networking, we dig into ZTNA from HPE’s perspective and hear customer stories on how it’s being used for third-party access, VPN consolidation,... Read more »

The Cutting Edge In Power Grid Management

Commissioned: Thanks to recent technological advancements, there are many different sources of electricity available which can help organizations address our growing demand for energy from power hungry devices such as electric vehicles while reducing their reliance on fossil fuels like petroleum, coal, and gas. …

The Cutting Edge In Power Grid Management was written by Timothy Prickett Morgan at The Next Platform.

Q1 2024 Internet disruption summary

This post is also available in 日本語, 한국어, Deutsch, Français, Español.

Cloudflare’s network spans more than 310 cities in over 120 countries, where we interconnect with over 13,000 network providers in order to provide a broad range of services to millions of customers. The breadth of both our network and our customer base provides us with a unique perspective on Internet resilience, enabling us to observe the impact of Internet disruptions. Thanks to recently released Cloudflare Radar functionality, this quarter we have started to explore the impact from a routing perspective, as well as a traffic perspective, at both a network and location level.

The first quarter of 2024 kicked off with quite a few Internet disruptions. Damage to both terrestrial and submarine cables caused problems in a number of locations, while military action related to ongoing geopolitical conflicts impacted connectivity in other areas. Governments in several African countries, as well as Pakistan, ordered Internet shutdowns, focusing heavily on mobile connectivity. Malicious actors known as Anonymous Sudan claimed responsibility for cyberattacks that disrupted Internet connectivity in Israel and Bahrain. Maintenance and power outages forced users offline, resulting in observed drops in traffic. And in Continue reading

netlab: Global and Node VRFs

When designing the netlab VRF configuration module, I tried to make it as flexible as possible while using the minimum number of awkward nerd knobs. As is often the case1, the results could be hard to grasp, so let’s walk through the various scenarios of using global and node VRFs.

netlab allows you to define a VRF in the lab topology vrfs dictionary (global VRF) or in a node vrfs dictionary (node VRF). In most cases, you’d define a few global VRFs and move on.

Read more …

netlab: Global and Node VRFs

When designing the netlab VRF configuration module, I tried to make it as flexible as possible while using the minimum number of awkward nerd knobs. As is often the case1, the results could be hard to grasp, so let’s walk through the various scenarios of using global and node VRFs.

netlab allows you to define a VRF in the lab topology vrfs dictionary (global VRF) or in a node vrfs dictionary (node VRF). In most cases, you’d define a few global VRFs and move on.

Read more …

Cisco vPC in VXLAN/EVPN Network – Part 1 – Anycast VTEP

Many vendors offer MLAG features, that is, the ability to form a PortChannel (some vendors call it trunk or bond) towards two separate devices. In this post, I will cover the following:

  • Briefly describe vPC in a traditional network.
  • Describe vPC in a VXLAN/EVPN network.
  • Configure leaf switches to support vPC.
  • Setup of Ubuntu Linux host to bond two interfaces and use LACP.
  • Verification of the setup.

Traditional vPC

On Cisco Nexus switches, virtual Port Channel (vPC) has been a highly used feature for many years. It has been used towards other network devices such as firewalls, routers, and switches, but also towards hosts running hypervisors such as ESX.

As opposed to other technologies such as Virtual Switching System (VSS) or StackWise Virtual, it does not require the two switches to become one to provide the ability to do MLAG. Instead, the two devices appear as one in PDUs such as LACP, STP, and IGMP, by using a vPC system MAC address as the source MAC. With MLAG features, the two switches need to verify the other is alive and also synchronize state and perform consistency checking. This is done by connecting them with a vPC peer keepalive link, and Continue reading

Single-AS EVPN Fabric with OSPF Underlay: Underlay Network Multicast Routing: Any-Source Multicast – ASM

 Underlay Network Multicast Routing: PIM-SM

In a traditional Layer 2 network, switches forward Intra-VLAN data traffic based on the destination MAC address of Ethernet frames. Therefore, hosts within the same VLAN must resolve each other's MAC-IP address bindings using Address Resolution Protocol (ARP). When a host wants to open a new IP connection with a device in the same subnet and the destination MAC address is unknown, the connection initiator generates an ARP Request message. In the message, the sender provides its own MAC-IP binding information and queries the MAC address of the owner of the target IP. The ARP Request messages are Layer 2 Broadcast messages with the destination MAC address FF:FF:FF:FF:FF:FF. 

EVPN Fabric is a routed network and requires a solution for Layer 2 Broadcast messages. We can select either BGP EVPN-based Ingress-Replication (IR) solution or enable Multicast routing in Underlay network. This chapter introduces the latter model. As in previous Unicast Routing section, we follow the Multicast deployment workflow of Nexus Dashboard Fabric Controller (NDFC) graphical user interface. 

Figure 2-4 depicts the components needed to deploy Multicast service in the Underlay network. The default option for selecting “RP mode” is ASM (Any-Source Multicast). ASM is Continue reading

Weekend Reads 042624


The Stanford Institute for Human-Centered Artificial Intelligence (HAI) has issued its seventh annual AI Index Report, which reports a thriving industry facing growing costs, regulations, and public concern.


At a time when no one expected progress on the U.S. federal privacy front, a new discussion draft for a comprehensive consumer privacy bill has emerged with bipartisan and bicameral support.


There is a new way for folks to track and spy on you. A recent article in the MIT Technology Review described how WiFi tracking has become a usable technology.


How would AI help produce victims? ‘Deep fake’ video technology. We previously saw, in ‘Human Impersonation AI Must be Outlawed,’ how extortion videos could target millions of individuals worldwide simultaneously every day.


A few weeks ago, I got a bit miffed reading yet another article that was too dismissive about memory safety, basically being mostly dismissive about the need for change.


Combined heat and power using waste heat recovery is a natural for AI/data centers deserves more consideration. We hope that we have lit that spark.


Larry Sanger remembers the promise of the web. He co-founded Wikipedia in 2001, with the hope that it could sustain a “free and open” Continue reading

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