I got this comment on one of my ChatGPT-related posts:
It does save time for things like converting output to YAML (I do not feed it proprietary information), or have it write scripts in various languages, converting configs from one vendor to another, although often they are not complete or correct they save time so regardless of what we think of it, it is an efficiency multiplier.
I received similar feedback several times, but found that the real answer (as is too often the case) is It Depends.
When I reposted a link to xBGP: Faster Innovation in Routing Protocols paper, someone immediately replied
Quite interesting, but it feels like this could become the proverbial 15th standard.
xBGP is an API that allows BGP users to implement routing policies (route selection, filtering, or propagation) that use attributes or mechanisms defined in newer IETF RFCs or drafts, so the proverbial 15th standard is not that far off the mark. However, we must remember that what we call BGP is more than just a set of competing standards.
When I reposted a link to xBGP: Faster Innovation in Routing Protocols paper, someone immediately replied
Quite interesting, but it feels like this could become the proverbial 15th standard.
xBGP is an API that allows BGP users to implement routing policies (route selection, filtering, or propagation) that use attributes or mechanisms defined in newer IETF RFCs or drafts, so the proverbial 15th standard is not that far off the mark. However, we must remember that what we call BGP is more than just a set of competing standards.
I always love to hear about real-life netlab use cases, and try to make them even easier to implement with new netlab features – that’s how netlab got custom Vagrant configuration templates and per-node configuration templates.
When Anne Baretta sent me his initial DMVPN solution, we quickly figured out we could make it even cleaner if netlab supported tunnel interfaces; you can enjoy the results in release 1.5.2, and explore Anne’s solution on GitHub.
I always love to hear about real-life netlab use cases, and try to make them even easier to implement with new netlab features – that’s how netlab got custom Vagrant configuration templates and per-node configuration templates.
When Anne Baretta sent me his initial DMVPN solution, we quickly figured out we could make it even cleaner if netlab supported tunnel interfaces; you can enjoy the results in release 1.5.2, and explore Anne’s solution on GitHub.
In case you ever wondered how old the “keep network simple and do complex stuff at the endpoints” approach is, read the End-to-End Arguments in System Design article from 1981.
For whatever reason (hint: profits), networking vendors keep ignoring those arguments, turning the network into a kitchen sink of complexity.
Fun tidbit: the article describes a variant of relying on layer-2 checksums will corrupt your data. Some things never change.
In case you ever wondered how old the “keep network simple and do complex stuff at the endpoints” approach is, read the End-to-End Arguments in System Design article from 1981.
For whatever reason (hint: profits), networking vendors keep ignoring those arguments, turning the network into a kitchen sink of complexity.
Fun tidbit: the article describes a variant of relying on layer-2 checksums will corrupt your data. Some things never change.
RFC 9386 documenting IPv6 deployment status in late 2022 has been published a few weeks ago1. It claims over a billion IPv6-capable users, and IPv6 deployment close to 50% in major countries.
Web content is a different story: while 40% of top-500 sites are IPv6-enabled, you can reach only ~20% of web sites over IPv6. Considering Cloudflare’s free proxying includes IPv6 that is enabled by default, that proves (once again) how slowly things change in IT.
RFC 9386 documenting IPv6 deployment status in late 2022 has been published a few weeks ago1. It claims over a billion IPv6-capable users, and IPv6 deployment close to 50% in major countries.
Web content is a different story: while 40% of top-500 sites are IPv6-enabled, you can reach only ~20% of web sites over IPv6. Considering Cloudflare’s free proxying includes IPv6 that is enabled by default, that proves (once again) how slowly things change in IT.
When 400GbE was still an emerging technology, Mark Nowell explained its basics in an update session of the Data Center Fabric Architectures webinar, starting with 400GbE optics.
When 400GbE was still an emerging technology, Mark Nowell explained its basics in an update session of the Data Center Fabric Architectures webinar, starting with 400GbE optics.
The Dynamic MAC Learning versus EVPN blog post triggered tons of interesting responses describing edge cases and vendor bugs implementation details, including an age-old case of silent hosts described by Nitzan:
Few years ago in EVPN network, I saw drops on the multicast queue (ingress replication goes to that queue). After analyzing it we found that the root cause is vMotion (the hosts in that VLAN are silent) which starts at a very high rate before the source leaf learns the destination MAC.
It turns out that the behavior they experienced was caused by a particularly slow EVPN implementation, so it’s not exactly the case of silent hosts, but let’s dig deeper into what could happen when you do have silent hosts attached to an EVPN fabric.
The Dynamic MAC Learning versus EVPN blog post triggered tons of interesting responses describing edge cases and vendor bugs implementation details, including an age-old case of silent hosts described by Nitzan:
Few years ago in EVPN network, I saw drops on the multicast queue (ingress replication goes to that queue). After analyzing it we found that the root cause is vMotion (the hosts in that VLAN are silent) which starts at a very high rate before the source leaf learns the destination MAC.
It turns out that the behavior they experienced was caused by a particularly slow EVPN implementation, so it’s not exactly the case of silent hosts, but let’s dig deeper into what could happen when you do have silent hosts attached to an EVPN fabric.
One of my subscribers found an unusual BGP specimen in the wild:
So far so good, and kudos to whoever realized BGP is the only sane protocol to run between virtual machines and network core. However, the routing in the network core was implemented with EBGP sessions between the three core devices, and my subscriber thought the correct way to do it would be to use IBGP and OSPF.
One of my subscribers found an unusual BGP specimen in the wild:
So far so good, and kudos to whoever realized BGP is the only sane protocol to run between virtual machines and network core. However, the routing in the network core was implemented with EBGP sessions between the three core devices, and my subscriber thought the correct way to do it would be to use IBGP and OSPF.
netlab release 1.5.2 brings another bunch of cool features, including:
I’ll cover these features in separate blog posts; today I wanted to highlight a few minor additions:
netlab release 1.5.2 brings another bunch of cool features, including:
I’ll cover these features in separate blog posts; today I wanted to highlight a few minor additions:
BGP zombies are routes in the BGP table that refuse to disappear even though they should have been long gone. Recent measurements estimate between 0.5% and 1.5% of all routes in the global BGP table are zombies, which sounds crazy – after all, BGP is supposed to be pretty reliable.
Daryll Swer identified one potential source – Juniper routers do not revoke suppressed aggregated prefixes – and documented it in Navigating a BGP zombie outbreak on Juniper routers.
BGP zombies are routes in the BGP table that refuse to disappear even though they should have been long gone. Recent measurements estimate between 0.5% and 1.5% of all routes in the global BGP table are zombies, which sounds crazy – after all, BGP is supposed to be pretty reliable.
Daryll Swer identified one potential source – Juniper routers do not revoke suppressed aggregated prefixes – and documented it in Navigating a BGP zombie outbreak on Juniper routers.
Want to know some details behind the CloudFlare SD-WAN implementation? You might find them in From IP packets to HTTP: the many faces of our Oxy framework.
I don’t know enough about Linux networking to figure out whether one could use those details to build something similar, but CloudFlare blog posts keep begin much better than Google’s Look How Awesome We Are recruitment drives.