Unexpected Interactions Between OSPF and BGP

It started with an interesting question tweeted by @pilgrimdave81

I’ve seen on Cisco NX-OS that it’s preferring a (ospf->bgp) locally redistributed route over a learned EBGP route, until/unless you clear the route, then it correctly prefers the learned BGP one. Seems to be just ooo but don’t remember this being an issue?

Ignoring the “why would you get the same route over OSPF and EBGP, and why would you redistribute an alternate copy of a route you’re getting over EBGP into BGP” aspect, Peter Palúch wrote a detailed explanation of what’s going on and allowed me to copy into a blog post to make it more permanent:

Read more …

Unexpected Interactions Between OSPF and BGP

It started with an interesting question tweeted by @pilgrimdave81

I’ve seen on Cisco NX-OS that it’s preferring a (ospf->bgp) locally redistributed route over a learned EBGP route, until/unless you clear the route, then it correctly prefers the learned BGP one. Seems to be just ooo but don’t remember this being an issue?

Ignoring the “why would you get the same route over OSPF and EBGP, and why would you redistribute an alternate copy of a route you’re getting over EBGP into BGP” aspect, Peter Palúch wrote a detailed explanation of what’s going on and allowed me to copy into a blog post to make it more permanent:

Read more …

Kubernetes Port Names and Terminating HTTPS Traffic on AWS

I recently came across something that wasn’t immediately intuitive with regard to terminating HTTPS traffic on an AWS Elastic Load Balancer (ELB) when using Kubernetes on AWS. At least, it wasn’t intuitive to me, and I’m guessing that it may not be intuitive to some other readers as well. Kudos to my teammates Hart Hoover and Brent Yarger for identifying the resolution, which I’m going to call out in this post.

This AWS Premium Support post outlines the basic scenario:

  • You’re running Kubernetes on AWS. The post references EKS, but as far as I know the issue is not limited to EKS, and should apply to self-managed Kubernetes clusters on AWS (assuming these clusters are configured with the AWS cloud provider).
  • You’ve published a Service of type LoadBalancer (which, in turn, creates a classic ELB). For self-managed clusters, this requires the AWS cloud provider to be installed and configured.
  • You want to terminate HTTPS traffic on the ELB. The post references the use of an ACM certificate, but I suspect it’s not limited to ACM certificates.

Consider the following YAML, taken directly from the previously-referenced AWS Premium Support article:

apiVersion: v1
kind: Service
metadata:
  name:  Continue reading

Network Break 338: Breach In Progress? Gigamon Operators Are Standing By; IEEE Finalizes New Ethernet Standard

Gigamon adds a human touch to a new SaaS NDR offering, the IEEE finalizes 802.3cu for faster speeds over single-mode optical fiber, US service providers roll out managed SASE services, and more IT news in this week's Network Break podcast.

The post Network Break 338: Breach In Progress? Gigamon Operators Are Standing By; IEEE Finalizes New Ethernet Standard appeared first on Packet Pushers.

The Week in Internet News: Biden Warns Putin About Some Cyberattacks

No-go zone: U.S. President Joe Biden told Russian President Vladimir Putin that some types of cyberattacks are off-limits during a meeting at the G7 summit in Switzerland recently, Reuters reports. Destructive attacks by Russian hackers on U.S. critical infrastructure must end, Biden said. It’s unclear if the talk will have much of an effect. Banned […]

The post The Week in Internet News: Biden Warns Putin About Some Cyberattacks appeared first on Internet Society.

Network Analysis 1. Setting up and Getting Started with Batfish in Multivendor Network with Cisco, Arista, and Cumulus.

Hello my friend,

The new year we start with a new topic, which is a configuration analysis of the multivendor networks. We have a passion both to create our own open source tools and to use existing, creating by other teams and project. Today we will start dive in one of such a tool.



1
2
3
4
5
No part of this blogpost could be reproduced, stored in a 

retrieval system, or transmitted in any form or by any 

means, electronic, mechanical or photocopying, recording, 

or otherwise, for commercial purposes without the 

prior permission of the author.

Network analysis as part of automation?

In software development we have a concept called CI/CD (Continuous Integration/Continuous Delivery). In a nutshell, it’s a methodology, which incorporates mandatory testing of configuration (code, software version, etc) before bringing it to production. The main idea behind it is that automated testing and validation will make sure that code is stable and fit for purpose. Automated testing? That’s where the automation comes to the stage.

And automation is something what we are experts in. And you can benefit from that expertise as well.

In our network automation training we follow zero to hero approach, where we Continue reading

Comparing EVPN with Flood-and-Learn Fabrics

One of ipSpace.net subscribers sent me this question after watching the EVPN Technical Deep Dive webinar:

Do you have a writeup that compares and contrasts the hardware resource utilization when one uses flood-and-learn or BGP EVPN in a leaf-and-spine network?

I don’t… so let’s fix that omission. In this blog post we’ll focus on pure layer-2 forwarding (aka bridging), a follow-up blog post will describe the implications of adding EVPN IP functionality.

Read more …

Comparing EVPN with Flood-and-Learn Fabrics

One of ipSpace.net subscribers sent me this question after watching the EVPN Technical Deep Dive webinar:

Do you have a writeup that compares and contrasts the hardware resource utilization when one uses flood-and-learn or BGP EVPN in a leaf-and-spine network?

I don’t… so let’s fix that omission. In this blog post we’ll focus on pure layer-2 forwarding (aka bridging), a follow-up blog post will describe the implications of adding EVPN IP functionality.

Read more …

When we’ll get a 128-bit CPU

On Hacker News, this article claiming "You won't live to see a 128-bit CPU" is trending". Sadly, it was non-technical, so didn't really contain anything useful. I thought I'd write up some technical notes.

The issue isn't the CPU, but memory. It's not about the size of computations, but when CPUs will need more than 64-bits to address all the memory future computers will have. It's a simple question of math and Moore's Law.


Today, Intel's server CPUs support 48-bit addresses, which is enough to address 256-terabytes of memory -- in theory. In practice, Amazon's AWS cloud servers are offered up to 24-terabytes, or 45-bit addresses, in the year 2020.

Doing the math, it means we have 19-bits or 38-years left before we exceed the 64-bit registers in modern processors. This means that by the year 2058, we'll exceed the current address size and need to move 128-bits. Most people reading this blogpost will be alive to see that, though probably retired.

There are lots of reasons to suspect that this event will come both sooner and later.

It could come sooner if storage merges with memory. We are moving away from rotating platters of rust toward solid-state Continue reading

1 … 703 704 705 706 707 … 3,836