Author Archives: Ivan Pepelnjak
Author Archives: Ivan Pepelnjak
Dinesh Dutt added another awesome chapter to the EVPN saga last week explaining how (and why) you could run VXLAN encapsulation with EVPN control plane on Linux hosts (TL&DR: think twice before doing it).
In the last part of current Azure Networking series I covered external VNet connectivity, including VNet peering, Internet access, Virtual Network Gateways, VPN connections, and ExpressRoute. The story continues on February 6th 2020 with Azure automation.
You’ll need Standard ipSpace.net Subscription to access both webinars.
Grouping the features needed in a networking stack in bunch of layered modules is a great idea, but unfortunately it turns out that you could place a number of important features like error recovery, retransmission and flow control in a number of different layers, from data link layer dealing with individual network segments to transport layer dealing with reliable end-to-end transmissions.
So where should we put those modules? As always, the correct answer is it depends, in this particular case on transmission reliability, latency, and cost of bandwidth. You’ll find more details in the Retransmissions and Flow Control part of How Networks Really Work webinar.
How nice would it be to have a fabric health dashboard displaying a summary of numerous parameters you’re interested in (number of operational uplinks, number of BGP sessions…) for every switch in your fabric.
I’m positive you could hack something together using the customization capabilities of your favorite network management system… or you could write a simple data gathering solution like Stephen Harding did while attending the Building Network Automation Solutions online course.
A while ago I had an interesting discussion with someone running VMware NSX on top of VXLAN+EVPN fabric - a pretty common scenario considering:
His fabric was running well… apart from the weird times when someone started tons of new VMs.Read more ...
A Docker networking rant coming from my good friend Marko Milivojević triggered a severe case of Deja-Moo, resulting in a flood of unpleasant memories caused by too-successful “disruptive” IT vendors.
Imagine you’re working for a startup creating a cool new product in the IT infrastructure space (if you have an oversized ego you would call yourself “disruptive thought leader” on your LinkedIn profile) but nobody is taking you seriously. How about some guerrilla warfare: advertising your product to people who hate the IT operations (today we’d call that Shadow IT).Read more ...
Have you ever seen an Ansible playbook where 90% of the code prepares the environment, and then all the work is done in a few template and assemble modules? Here’s an alternative way of getting that done. Is it better? You tell me ;)
Anycast (advertising the same IP address from multiple servers/locations) has long been used to implement scale-out public DNS services (the whole root DNS system runs on massive anycast), but it’s not as common in enterprise networks.
Want to know even more? I covered numerous load balancing mechanisms including anycast in Data Centers Infrastructure for Networking Engineers webinar.
A while ago Johannes Weber tweeted about an interesting challenge:
We want to advertise our AS and PI space over a single ISP connection. How would a setup look like with 2 Cisco routers, using them for hardware redundancy? Is this possible with only 1 neighboring to the ISP?
Hmm, so you have one cable and two router ports that you want to connect to that cable. There’s something wrong with this picture ;)Read more ...
Remember Nicky Davey describing how he got large DMVPN deployment back on track with configuration templating? In his own words…:
Configuration templating is still as big win a win for us as it was a year ago. We have since expanded the automation solution, and reading the old blog post makes me realise how far we have come. I began working with this particular customer in May 2017, so 2 years now. At that time the new WAN project was on the horizon and the approach to network configuration was entirely manual.
Here’s how far he got in the meantime:Read more ...
We also had a great guest speaker on the Network Automation course: Damien Garros explained how he used central source-of-truth based on NetBox and Git to set up a network automation stack from the grounds up.
Recordings are already online; you’ll need Standard ipSpace.net Subscription to access the Azure Networking webinar, and Expert ipSpace.net Subscription to access Damien’s presentation. Azure Networking webinar is also part of our new Networking in Public Clouds online course.
This is a guest blog post by Philippe Jounin, Senior Network Architect at Orange Business Services.
You could use track objects in Cisco IOS to track route reachability or metric, the status of an interface, or IP SLA compliance for a long time. Initially you could use them to implement reliable static routing (or even shut down a BGP session) or trigger EEM scripts. With a bit more work (and a few more EEM scripts) you could use object tracking to create time-dependent static routes.
Cisco IOS 15 has introduced Enhanced Object Tracking that allows first-hop router protocols like VRRP or HSRP to use tracking state to modify their behavior.Read more ...
I have exciting news I’d love to share with you: we’re launching a new online course focused on networking in public clouds starting in February 2020 (I’ve been mulling over this idea and polishing the concept for almost 18 months, and finally it all came together ;)
With Go To The Cloud becoming the answer to all questions (regardless of what the question is), you can find tons of materials describing various aspects of public clouds, so you might wonder why I decided to enter the fray. The answer is simple: with everyone being focused on developers, there’s not much that an infrastructure engineer could use to help him survive when the developers move on and he’s left to manage whatever they put in place.Read more ...
Every few weeks I stumble upon an article (or twitter storm) in which someone claims you don’t need formal education to get started as a Software Engineer (or whatever else) - all you need is a coding academy/bootcamp and you're all set.
George V. Neville-Neil wrote a hilarious rebuttal of this idea followed by some pretty good advice. Hope you’ll enjoy it as much as I did ;)
A long while ago Daniel Dib wrote a nice blog post on “SDN will make the networking engineers obsolete” theme. While it sounds like beating a dead horse, the SDN craze isn’t subsiding, so another healthy dose of common sense might come handy.
Hint: if you’re not following Daniel’s blog, you should… even though he decided to make old farts’ life harder by publishing on LinkedIn.
Sick-and-tired of intent-based GUIs that are barely better than CiscoWorks on steroids? How about asking Siri-like assistant queries about network state in somewhat-limited English and getting replies back in full-blown sentences?
The autumn 2019 webinar season is in full swing ;) We’re almost done with Azure Networking webinar (the last session will take place on October 10th) and the network automation course is nicely chugging along – a few weeks ago Matthias Luft talked about supply-chain security in open-source software and today we’ll enjoy the start with a single source of truth presentation by Damien Garros.
Dinesh Dutt is coming back on October 8th with another installment of EVPN saga, this time focused on running EVPN on Linux hosts, and on October 22nd Donald Sharp will tell us all about the underlying magic box – the Free Range Routing software.
A while ago Ruben Tripiana tried to configure BGP on Cisco IOS using IETF YANG data models… and failed. In Spring 2019 Building Network Automation Solutions online course Chris Crook decided to deploy BGP routing on multiple platforms using YANG data models instead of configuration templates. Not only did he succeed, he also documented his work and the tools he used, and published the solution so you can replicate his efforts.
You can find many more network automation solutions created by the attendees of our automation course in solutions showcase.
Two weeks ago I replied to a battle-scar reaction to 7-layer OSI model, this time I’ll address a much more nuanced view from Russ White. Please read his article first (as always, it’s well worth reading) and when you come back we’ll focus on this claim:
The OSI Model does not accurately describe networks.
Like with any tool in your toolbox, you can view the 7-layer OSI model in a number of ways. In the case of OSI model, it can be used:Read more ...
In last week’s continuation of EVPN never-ending story Lukas Krattiger described how you could use EVPN constructs (VNIs, VRFs) to implement service insertion, and how you could combine then with policy-based routing.
TL&DW: It’s bridging and routing ;)
You’ll need Standard ipSpace Subscription to access the videos.