EVPN/VXLAN Complexity
We have school holidays this week, so I’m reposting wonderful comments that would otherwise be lost somewhere in the page margins. Today: Minh Ha on complexity of emulating layer-2 networks with VXLAN and EVPN.
Dmytro Shypovalov is a master networker who has a sophisticated grasp of some of the most advanced topics in networking. He doesn’t write often, but when he does, he writes exceptional content, both deep and broad. Have to say I agree with him 300% on “If an L2 network doesn’t scale, design a proper L3 network. But if people want to step on rakes, why discourage them.”
EVPN/VXLAN Complexity
We have school holidays this week, so I’m reposting wonderful comments that would otherwise be lost somewhere in the page margins. Today: Minh Ha on complexity of emulating layer-2 networks with VXLAN and EVPN.
Dmytro Shypovalov is a master networker who has a sophisticated grasp of some of the most advanced topics in networking. He doesn’t write often, but when he does, he writes exceptional content, both deep and broad. Have to say I agree with him 300% on “If an L2 network doesn’t scale, design a proper L3 network. But if people want to step on rakes, why discourage them.”
Interactions Between BFD and Graceful Restart
We have school holidays this week, so I’m reposting wonderful comments that would otherwise be lost somewhere in the page margins. Today: Dmitry Perets on the interactions between BFD and GR.
Well, assuming that the C-bit is set honestly (will be funny if not) and assuming that the Helper is using this bit correctly (and I think it’s pretty well defined what “correctly” means - see section 4.3 in RFC 5882), the answer is pretty clear.
Interactions Between BFD and Graceful Restart
We have school holidays this week, so I’m reposting wonderful comments that would otherwise be lost somewhere in the page margins. Today: Dmitry Perets on the interactions between BFD and GR.
Well, assuming that the C-bit is set honestly (will be funny if not) and assuming that the Helper is using this bit correctly (and I think it’s pretty well defined what “correctly” means - see section 4.3 in RFC 5882), the answer is pretty clear.
Feedback: How Networks Really Work
A few weeks ago I asked my subscribers which webinar they’d like to see in November (thanks a million to everyone who replied!). Not surprisingly, network automation got the top spot, but I was a bit sad to see my long-term pet project at the bottom of the list:
Feedback: How Networks Really Work
A few weeks ago I asked my subscribers which webinar they’d like to see in November (thanks a million to everyone who replied!). Not surprisingly, network automation got the top spot, but I was a bit sad to see my long-term pet project at the bottom of the list:
Worth Reading: Making a Case for Automation Architecture
In case you’re ever asked to justify an investment in network automation, read How to Make the Case for Automation Architecture first. Not surprisingly, it includes the evergreen what problem are you trying to solve?
Worth Reading: Making a Case for Automation Architecture
In case you’re ever asked to justify an investment in network automation, read How to Make the Case for Automation Architecture first. Not surprisingly, it includes the evergreen what problem are you trying to solve?
Worth Reading: Network Validation Evolution at Hostinger
Network validation is becoming another overhyped buzzword with many opinionated pundits talking about it and few environments using it in practice (why am I not surprised?)
As always, there are exceptions. They don’t have to be members of the FAANG club, and some of them get the job done with open-source tools regardless of what vendor marketers would like you to believe. For example, Donatas Abraitis described how the Hostinger networking team gradually implemented network validation using Cumulus VX, Vagrant, SuzieQ, PyTest and Test Kitchen. Enjoy!
Worth Reading: Network Validation Evolution at Hostinger
Network validation is becoming another overhyped buzzword with many opinionated pundits talking about it and few environments using it in practice (why am I not surprised?)
As always, there are exceptions. They don’t have to be members of the FAANG club, and some of them get the job done with open-source tools regardless of what vendor marketers would like you to believe. For example, Donatas Abraitis described how the Hostinger networking team gradually implemented network validation using Cumulus VX, Vagrant, SuzieQ, PyTest and Test Kitchen. Enjoy!
Video: Introduction to AI/ML Hype
In May 2021, Javier Antich ran a great webinar explaining the principles of Artificial Intelligence and Machine learning and how they apply (or not) to networking.
He started with a brief overview of AI/ML hype that should help you understand why there’s a bit of a difference between self-driving cars (not that we got there) and self-driving networks.
You need Free ipSpace.net Subscription to access this webinar.
Video: Introduction to AI/ML Hype
In May 2021, Javier Antich ran a great webinar explaining the principles of Artificial Intelligence and Machine learning and how they apply (or not) to networking.
He started with a brief overview of AI/ML hype that should help you understand why there’s a bit of a difference between self-driving cars (not that we got there) and self-driving networks.
You need Free ipSpace.net Subscription to access this webinar.
Circular Dependencies Considered Harmful
A while ago my friend Nicola Modena sent me another intriguing curveball:
Imagine a CTO who has invested millions in a super-secure data center and wants to consolidate all compute workloads. If you were asked to run a BGP Route Reflector as a VM in that environment, and would like to bring OSPF or ISIS to that box to enable BGP ORR, would you use a GRE tunnel to avoid a dedicated VLAN or boring other hosts with routing protocol hello messages?
While there might be good reasons for doing that, my first knee-jerk reaction was:
Circular Dependencies Considered Harmful
A while ago, my friend Nicola Modena sent me another intriguing curveball:
Imagine a CTO who has invested millions in a super-secure data center and wants to consolidate all compute workloads. If you were asked to run a BGP Route Reflector as a VM in that environment, and would like to bring OSPF or ISIS to that box to enable BGP ORR, would you use a GRE tunnel to avoid a dedicated VLAN or boring other hosts with routing protocol hello messages?
While there might be good reasons for doing that, my first knee-jerk reaction was:
Do We Need Multiple Global IPv6 Addresses Per Interface (RFC 7934)
I was happily munching popcorn while watching the latest season of Lack of DHCPv6 on Android soap opera on v6ops mailing list when one of the lead actors trying to justify the current state of affairs with a technical argument quoted an RFC to prove his rightful indignation with DHCPv6 and the decision not to implement it in Android:
[…not having multiple IPv6 addresses per interface…] is also harmful for a variety of reasons, and for general purpose devices, it’s not recommended by the IETF. That’s exactly what RFC 7934 is about - explaining why it’s harmful.
If you’re new to this discussion, you might want to start with Why Does DHCPv6 Matter blog post
Do We Need Multiple Global IPv6 Addresses Per Interface (RFC 7934)
I was happily munching popcorn while watching the latest season of Lack of DHCPv6 on Android soap opera on v6ops mailing list when one of the lead actors trying to justify the current state of affairs with a technical argument quoted an RFC to prove his rightful indignation with DHCPv6 and the decision not to implement it in Android:
[…not having multiple IPv6 addresses per interface…] is also harmful for a variety of reasons, and for general purpose devices, it’s not recommended by the IETF. That’s exactly what RFC 7934 is about - explaining why it’s harmful.
If you’re new to this discussion, you might want to start with Why Does DHCPv6 Matter blog post
Graceful Restart and BFD
The whole High Availability Switching series started with a question along the lines of “does it make sense to run BFD together with Graceful Restart”. After Non-Stop Forwarding 101, Graceful Restart 101, and Graceful Restart and Convergence Speed we finally have enough information to answer that question.
TL&DR: Most probably not.
A more nuanced answer depends (as always) on a gazillion implementation details.
Graceful Restart and BFD
The whole High Availability Switching series started with a question along the lines of “does it make sense to run BFD together with Graceful Restart”. After Non-Stop Forwarding 101, Graceful Restart 101, and Graceful Restart and Convergence Speed we finally have enough information to answer that question.
TL&DR: Most probably not.
A more nuanced answer depends (as always) on a gazillion implementation details.
netsim-tools: Start a Virtual Lab with a Single Command
In mid-October I finally found time to add the icing to the netsim-tools cake: netlab up command takes a lab topology and does everything needed to have a running virtual lab:
- Create Vagrantfile or containerlab topology file
- Create Ansible inventory
- Start the lab with vagrant up or containerlab deploy
- Deploy device configurations, from LLDP and interface addressing to routing protocols and Segment Routing
Start a Virtual Lab with a Single Command
In mid-October I finally found time to add the icing to the netlab cake: netlab up command takes a lab topology and does everything needed to have a running virtual lab:
- Create Vagrantfile or containerlab topology file
- Create Ansible inventory
- Start the lab with vagrant up or containerlab deploy
- Deploy device configurations, from LLDP and interface addressing to routing protocols and Segment Routing