Author Archives: Ivan Pepelnjak
Author Archives: Ivan Pepelnjak
It’s time for a Halloween story: imagine the scary scenario in which a DHCP client asks for an address, gets it, and then immediately declines it. That’s what I’ve been experiencing with vJunos Evolved release 23.2R1.15.
Before someone gets the wrong message: I’m not criticizing Juniper or vJunos.
However, it looks like something broke in vJunos release 23.2, and it would be nice to figure out what the workaround might be.
My good friend Tiziano Tofoni finally created an English version of his evergreen classic BGP from theory to practice with co-authors Antonio Prado and Flavio Luciani.
I had the Italian version of the book since the days I was running SDN workshops with Tiziano in Rome, and it’s really nice to see they finally decided to address a wider market.
Also, you know what would go well with that book? Free open-source BGP configuration labs of course 😉
After covering the theoretical part of network addressing (part 2, part 3), let’s go into some practical examples. I’ll start with data link layer and then move on to networking and higher layers.
The earliest data link implementations that were not point-to-point links were multi-drop links and I mentioned them in the networking challenges part of the webinar. Initially, we implemented multi-drop links with modems, but even today you can see multi-drop in satellite communications, Wi-Fi, or in cable modems.
A quick update BGP Labs project status update: now that netlab release 1.6.4 is out I could remove the dependency on using Cumulus Linux as the external BGP router.
You can use any device that is supported by bgp.session and bgp.policy plugins as the external BGP router. You could use Arista EOS, Aruba AOS-CX, Cisco IOSv, Cisco IOS-XE, Cumulus Linux or FRR as external BGP routers with netlab release 1.6.4, and I’m positive Jeroen van Bemmel will add Nokia SR Linux to that list.
If you’re not ready for a netlab upgrade, you can keep using Cumulus Linux as external BGP routers (I’ll explain the behind-the-scenes magic in another blog post, I’m at the Deep Conference this week).
For more details read the updated BGP Labs Software Installation and Lab Setup guide.
Features in netlab release 1.6.4 were driven primarily by the needs of my BGP labs project:
Numerous platforms already support the new BGP nerd knobs:
I’ll be talking about Internet routing security at the Deep conference in a few days, and just in case you won’t be able to make it1 ;) here’s the first bit of my talk: a very brief history of BGP route leaks2.
Note: you’ll find more Network Security Fallacies videos in the How Networks Really Work webinar.
After going through the BGP basics, it’s time to build a network that has more than one BGP router in it, starting with the simplest possible topology: a site with two WAN edge routers.
TL&DR: Violating the Betteridge’s Law of Headlines, the answer is “Yes, but the devil is in the details.”
It all started with the following observation by Minh Ha left as a comment to my previous BGP session security blog post:
I’d think it’d be obvious for BGP routers to only accept incoming sessions from configured BGP neighbors, right? Because BGP is the most critical infrastructure, the backbone of the Internet, why would you want your router to accept incoming session from anyone but KNOWN sources?
Following my “opinions are good, facts are better” mantra, I decided to run a few tests before opinionating1.
Bruce Schneier wrote a thoughtful article on the various perceptions of AI Risks including this gem:
As the science-fiction author Ted Chiang has said, fears about the existential risks of AI are really fears about the threat of uncontrolled capitalism, and dystopias like the paper clip maximizer are just caricatures of every start-up’s business plan.
Enjoy!
A few days after I published the EBGP session protection lab, Jeroen van Bemmel submitted a pull request that added TCP-AO support to netlab. Now that the release 1.6.3 is out, I could use it to build the Protect BGP Sessions with TCP Authentication Option (TCP-AO) lab exercise.
netlab release 1.6.3 added numerous BGP nerd knobs:
We also:
I encountered several articles explaining the challenges of simulating your network in a virtual lab in the last few months, including:
Enjoy!
Numerous Internet Exchange Points (IXP) started using VXLAN years ago to replace tradition layer-2 fabrics with routed networks. Many of them tried to avoid the complexities of EVPN and used VXLAN with statically-configured (and hopefully automated) ingress replication.
A few went a step further and decided to deploy EVPN, primarily to deploy Proxy ARP functionality on EVPN switches and reduce the ARP/ND traffic. Thomas King from DE-CIX described their experience on APNIC blog – well worth reading if you’re interested in layer-2 fabrics.
A few years ago, I was asked to deliver a What Is SDDC presentation that later became a webinar. I forgot about that webinar until I received feedback from one of the viewers a week ago:
If you like to learn from the teachers with the “straight to the point” approach and complement the theory with many “real-life” scenarios, then ipSpace.net is the right place for you.
I haven’t realized people still find that webinar useful, so let’s make it viewable without registration, starting with What Problem Are We Trying to Solve and What Is SDDC.
netlab release 1.6.2 improved reporting capabilities:
In other news:
In the BGP Route Aggregation lab you can practice:
Note: if you want to keep things simple, run BGP labs with netlab (other options).
If you’re monitoring the industry press (or other usual hype factories), you might have heard about Ultra Ethernet, a dazzling new technology that will be developed by the Ultra Ethernet Consortium1. What is it and does it matter to you (TL&DR: probably not2)?
As always, let’s start with What Problem Are We Solving?
A while ago I explained how Generalized TTL Security Mechanism could be used to prevent denial-of-service attacks on routers running EBGP. Considering the results published in Analyzing the Security of BGP Message Parsing presentation from DEFCON 31 I started wondering how well GTSM implementations work.
TL&DR summary:
Dip Singh wrote another interesting article describing how ECMP load balancing implementations work behind the scenes. Absolutely worth reading.
Lindsay Hill described an excellent idea: all ports on your switches routers should be in link aggregation groups even when you have a single port in a group. That approach allows you to:
It also proves RFC 1925 rule 6a, but then I guess we’re already used to that ;)