VXLAN/EVPN – Host ARP

In the last post Advertising IPs In EVPN Route Type 2, I described how to get IPs advertised in EVPN route type 2, but why do we need it? There are three main scenarios where having the MAC/IP mapping is useful:

  • Host ARP.
  • Host mobility.
  • Host routing.

In this post I will cover the first use case and the topology below will be used:

Host ARP

When two hosts in the same subnet want to send Ethernet frames to each other, they will ARP to discover the MAC address of the other host. This is no different in a VXLAN/EVPN network. The ARP frame, which is broadcast, will have to be flooded to other VTEPs either using multicast in the underlay or by ingress replication. Because the frame is broadcast, it will have to go to all the VTEPs that have that VNI. The scenario with ingress replication is shown below:

In this scenario, SERVER-1 is sending an ARP request to get the MAC address of SERVER-4. As all leafs are participating in the L2 VNI, LEAF-1 will perform ingress replication and send it to all leafs. However, sending the ARP request to LEAF-2 and LEAF-3 is not needed Continue reading

On Routing Protocol Metrics

This LinkedIn snippet just came in from the someone is not exactly right on the Internet department:

Unlike IGP protocols, BGP is not dependent on a single type of metric to choose the best path.

EIGRP is an immediate counterexample that brought the above quote to my attention, but it’s worth exploring the topic in more detail.

Read more …

On Routing Protocol Metrics

This LinkedIn snippet just came in from the someone is not exactly right on the Internet department:

Unlike IGP protocols, BGP is not dependent on a single type of metric to choose the best path.

EIGRP is an immediate counterexample that brought the above quote to my attention, but it’s worth exploring the topic in more detail.

Read more …

The Future We Simulate Is The One We Create

Investment in supercomputing and related HPC technologies is not just a sign of how much we are willing to bet on the future with someone else’s money, but how much we believe in it ourselves, and more importantly, how much we believe in the core idea that we can predict and therefore shape the future of the world. …

The post The Future We Simulate Is The One We Create first appeared on The Next Platform.

The Future We Simulate Is The One We Create was written by Timothy Prickett Morgan at The Next Platform.

BGP in 2023 – Have we reached Peak IPv4?

At the start of each year, I’ve been reporting on the behaviour of the Internet’s inter-domain routing system over the previous 12 months, looking in some detail at some metrics from the routing system that can show the essential shape and behaviour of the underlying interconnection fabric of the Internet. The year 2023 marks a significant point in the evolution of the Internet where the strong growth numbers that were a constant feature of the past thirty years are simply not present in the data. Not only is the Internet’s growth slowing down significantly, but in the IPv4 network it appears to be shrinking, which is unprecedented in the brief history of the Internet to date.

BGP in 2023 – Have we reached Peak IPv4?

At the start of each year, I’ve been reporting on the behaviour of the Internet’s inter-domain routing system over the previous 12 months, looking in some detail at some metrics from the routing system that can show the essential shape and behaviour of the underlying interconnection fabric of the Internet. The year 2023 marks a significant point in the evolution of the Internet where the strong growth numbers that were a constant feature of the past thirty years are simply not present in the data. Not only is the Internet’s growth slowing down significantly, but in the IPv4 network it appears to be shrinking, which is unprecedented in the brief history of the Internet to date.

HN715: Prescribing The Right Dose Of Automation For A Hospital Network

At NewYork-Presbyterian Hospital, patients are the priority. That focus on patient care extends to the hospital’s campus network, data center, wireless network, and SD-WAN. These networks are instrumental for delivering medical applications and connecting medical devices. On today’s Heavy Networking, we talk with network architects and engineers at NewYork-Presbyterian about their use of automation to... Read more »

HN715: Prescribing The Right Dose Of Automation For A Hospital Network

We talk with network architects and engineers at NewYork-Presbyterian Hospital about their automation strategy for mission-critical networks that support patient care. We explore the automation progress they've made, long-term goals, technical and cultural challenges, what they'd like to see from vendors, and more.

The post HN715: Prescribing The Right Dose Of Automation For A Hospital Network appeared first on Packet Pushers.

Weekend Reads 011524

Thanks to Mark Prosser for a few links to add to the pile this week.


There’s a rumor flying around the Internet that OpenAI is training foundation models on your Dropbox documents.


Microsoft found that a popular form of video-based training reduces phish-clicking behavior by about 3%, at best. This number has been stable over the years, says Microsoft, while phishing attacks are increasing yearly.


The Internet Architecture Board (IAB) has warned that policy proposals requiring or enabling the automated scouring of people’s devices for illegal material – as floated by the European Union, the United Kingdom, and the United States – threaten the open internet.


Another update of the Ultimate PCAP is available. Again, there are some special new packets in there which I want to point out here. Feel free to download the newest version to examine those new protocols and packets by yourself. Featuring: SNMPv3, WoL, IPMI, HSRP, Zabbix, Pile of Poo, and Packet Comments.


The Genesis Market began operating in 2017, four years after Silk Road closed shop. Like its predecessor, though, the Federal Bureau of Investigation (FBI) and other law enforcement agencies took the Genesis Market down last April.


Miyake events are believed to be Continue reading

Technology Short Take 172

Welcome to Technology Short Take #172, the first Technology Short Take of 2024! This one is really short, which I’m assuming reflects a lack of blogging activity over the 2023 holiday season. Nevertheless, I have managed to scrape together a few links to share with readers. As usual, I hope you find something useful. Enjoy!

Networking

  • Via this blog post, I learned that Ivan Pepelnjak has a GitHub repository of hands-on examples for learning public cloud networking (including both AWS and Azure). Ivan’s materials are always excellent, so if you’re looking for resources to help with expanding your networking skills into the public cloud, this should be on the short list. (I plan to submit a PR soon to add Pulumi examples, which the repository is currently missing.)

Cloud Computing/Cloud Management

  • Jonathan Major shares his experience using Pulumi with Google Cloud APIs. I think there are some code snippets in Jonathan’s article, but my instance of Firefox wouldn’t render the code snippets (instead only showing empty black boxes).
  • Nisar Ahmad explores whether Terraform or Pulumi is better for your use case.

Operating Systems/Applications

Public Videos: Routing Protocols

One of the delightful side effects of leaving the paid content business is that I no longer have to try to persuade anyone that my content is any good. That includes the “this video is now public” announcements – instead of elaborate introductions, I’ll just publish a short blog post with the links.

As of today, these videos (along with dozens of previously-released videos) from the Routing Protocols section of the How Networks Really Work webinar are no longer behind a login wall:

Read more …

Advertising IPs In EVPN Route Type 2

In my last post EVPN Deepdive Route Types 2 and 3, we took a deepdive into these two route types. I mentioned that the IP address of a host, a /32 or /128 address, could optionally be advertised. I also mentioned that this is mainly to facilitate features such as ARP suppression where a VTEP will be aware of the MAC/IP mapping and not have to flood BUM frames. However, in my last lab no IP addresses were advertised. Why is that? How do we get them advertised?

Currently, I have only setup a L2 VNI in the lab. This provides connectivity for the VLAN that my hosts are in, but it does not provide any L3 services. There is no SVI configured and there is also no L3 service configured that can route between different VNIs. The “standard” way of setting this up would be to configure anycast gateway on the leafs where every leaf that hosts the VNI has the same IP/MAC, but I consider this to be an optimization that I want to cover in a future posts. I prefer to break things down into their components and focus on the configuration needed for each component Continue reading

KU044: Making Kubernetes And Cloud-Native Workloads Environmentally Sustainable

Can clouds be green? Today we discuss sustainability in the tech industry, focusing on running Kubernetes and workloads in more efficient and environmentally friendly ways. Co-hosts Kristina Devochko and Michael Levan explore current tools, the reuse of resources like excess heat from data centers, and the challenges of sustainable energy infrastructure, such as electric cars... Read more »
1 … 173 174 175 176 177 … 3,835