The Recursive BGP Next Hops: an RFC 4271 Quirk blog post generated tons of feedback (thanks a million to everyone writing a comment on my blog or LinkedIn).
Starting with Robert Razsuk who managed to track down the original email that triggered the (maybe dubious) text in RFC 4271:
The text in section 5.1.3 was not really targeting to prohibit load balancing. Keep in mind that it is FIB layer which constructs actual forwarding paths.
The text has been suggested by Tom Petch in discussion about BGP advertising valid paths or even paths it actually installs in the RIB/FIB. The entire section 5.1.3 is about rules when advertising paths by BGP.
The Recursive BGP Next Hops: an RFC 4271 Quirk blog post generated tons of feedback (thanks a million to everyone writing a comment on my blog or LinkedIn).
Starting with Robert Razsuk who managed to track down the original email that triggered the (maybe dubious) text in RFC 4271:
The text in section 5.1.3 was not really targeting to prohibit load balancing. Keep in mind that it is FIB layer which constructs actual forwarding paths.
The text has been suggested by Tom Petch in discussion about BGP advertising valid paths or even paths it actually installs in the RIB/FIB. The entire section 5.1.3 is about rules when advertising paths by BGP.
New Year break was probably my busiest time (programming-wise) in years. Jeroen van Bemmel continued generating great ideas (and writing code and device configuration templates), and I found myself saying, “why not, let’s do the right thing!” more often than I expected. In parallel, Stefano Sasso fixed configuration templates for Junos, Mikrotik Router OS, and VyOS, and we were good to go.
To give you an idea of how fast we were moving: issue #84 was created on December 22nd, Sunday’s pull request that pushed release 1.1 into the master branch was #135 (GitHub numbers everything you do sequentially).
New Year break was probably my busiest time (programming-wise) in years. Jeroen van Bemmel continued generating great ideas (and writing code and device configuration templates), and I found myself saying, “why not, let’s do the right thing!” more often than I expected. In parallel, Stefano Sasso fixed configuration templates for Junos, Mikrotik Router OS, and VyOS, and we were good to go.
To give you an idea of how fast we were moving: issue #84 was created on December 22nd, Sunday’s pull request that pushed release 1.1 into the master branch was #135 (GitHub numbers everything you do sequentially).
Remember the unnumbered IP interfaces saga? Let’s conclude it with the final challenge: can we run link-state routing protocols (OSPF or IS-IS) over unnumbered interfaces?
Quick answer: Sure, just use IPv6.
Cheater! IPv6 doesn’t count. There are no unnumbered interfaces in IPv6 – every interface has at least a link-local address (LLA). Even more, routing protocols are designed to run over LLA addresses, including some EBGP implementations, allowing you to build an LLA-only network (see RFC 7404 for details).
OK, what about IPv4?
TL&DR: It works, but…
Remember the unnumbered IP interfaces saga? Let’s conclude with the final challenge: can we run link-state routing protocols (OSPF or IS-IS) over unnumbered interfaces?
Quick answer: Sure, just use IPv6.
Cheater! IPv6 doesn’t count. There are no unnumbered interfaces in IPv6 – every interface has at least a link-local address (LLA). Even more, routing protocols are designed to run over LLA addresses, including some EBGP implementations, allowing you to build an LLA-only network (see RFC 7404 for details).
OK, what about IPv4?
TL&DR: It works, but…
I’m positive that this pointer to The Gift of It’s Your Problem Now by Avery Pennarun will generate similar comments to the blockchain one: “he’s an idiot, and you’re an idiot for wasting my time posting this”.
That might be true, but in that case he’s my kind of idiot, and you shouldn’t complain about a gift anyway – there are tons of high-quality lolcats videos waiting for you instead.
I’m positive that this pointer to The Gift of It’s Your Problem Now by Avery Pennarun will generate similar comments to the blockchain one: “he’s an idiot, and you’re an idiot for wasting my time posting this”.
That might be true, but in that case he’s my kind of idiot, and you shouldn’t complain about a gift anyway – there are tons of high-quality lolcats videos waiting for you instead.
Remember the Cloud Models, Layers and Responsibilities video by Matthias Luft? He continued his introduction of cloud services with Cloud Services Hierarchy, explained the differences between infrastructure, platform, function and software as a service, and concluded with a there’s no free lunch message.
Remember the Cloud Models, Layers and Responsibilities video by Matthias Luft? He continued his introduction of cloud services with Cloud Services Hierarchy, explained the differences between infrastructure, platform, function and software as a service, and concluded with a there’s no free lunch message.
In 2021, we completed one of the longest ipSpace.net webinars: Cisco ACI Deep Dive (almost 13 hours of content1). One of the participants found it extremely useful:
I really like the technical detail of the webinar and the way it is composed. Mario also does a good job in explaining all the complexity in a clear way without oversimplifying. All the sessions help to build up an understanding on the inner workings of the ACI solution, because they deliver technical details in depth piece by piece.
I also liked his take on the value of this webinar:
I’m always amazed on how much other (offical) training vendors under deliver in their courses that cost thousands of dollars, compared to the real expert level stuff you’ve got here.
Hope you’ll like the webinar as much as he did – you can get it with Standard or Expert ipSpace.net Subscription.
In 2021, we completed one of the longest ipSpace.net webinars: Cisco ACI Deep Dive (almost 13 hours of content1). One of the participants found it extremely useful:
I really like the technical detail of the webinar and the way it is composed. Mario also does a good job in explaining all the complexity in a clear way without oversimplifying. All the sessions help to build up an understanding on the inner workings of the ACI solution, because they deliver technical details in depth piece by piece.
I also liked his take on the value of this webinar:
I’m always amazed on how much other (offical) training vendors under deliver in their courses that cost thousands of dollars, compared to the real expert level stuff you’ve got here.
Hope you’ll like the webinar as much as he did – you can get it with Standard or Expert ipSpace.net Subscription.
All BGP implementations I’ve seen so far use recursive next hop lookup:
Furthermore, all BGP implementations I’ve seen used multiple recursive next hops (if available) to implement load balancing toward the BGP next hop – that’s how we made EBGP load balancing work in Stone Age of networking.
All BGP implementations I’ve seen so far use recursive next hop lookup:
Furthermore, all BGP implementations I’ve seen used multiple recursive next hops (if available) to implement load balancing toward the BGP next hop – that’s how we made EBGP load balancing work in Stone Age of networking.
While I liked reading the Where to Stick the Firewall blog post by Peter Welcher, it bothered me a bit that he used microsegmentation to mean security groups.
I know that microsegmentation became approximately as well-defined as cloud or SDN1, but let’s aim our shiny lance 2 at the nearest windmill and gallop away…
While I liked reading the Where to Stick the Firewall blog post by Peter Welcher, it bothered me a bit that he used microsegmentation to mean security groups.
I know that microsegmentation became approximately as well-defined as cloud or SDN1, but let’s aim our shiny lance 2 at the nearest windmill and gallop away…
Tons of new things were added to netsim-tools in December 2021:
But wait, there’s more ;)
Tons of new things were added to netsim-tools in December 2021:
It’s hard to believe, but another year has swooshed by, and it’s time to shut down my virtual office and disappear until mid-January. Of course I’ll be around in case of urgent support problems – I will read my email, but won’t reply to 90% of the stuff coming in.
I hope you’ll be able to find a few days to disconnect from the crazy pace of networking world and focus on your loved ones. I would also like to wish you all the best in 2022!
It’s hard to believe, but another year has swooshed by, and it’s time to shut down my virtual office and disappear until mid-January. Of course I’ll be around in case of urgent support problems – I will read my email, but won’t reply to 90% of the stuff coming in.
I hope you’ll be able to find a few days to disconnect from the crazy pace of networking world and focus on your loved ones. I would also like to wish you all the best in 2022!