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Category: performance

Worth Reading: SD-WAN Scalability Challenges

In January 2020 Doug Heckaman documented his experience with VeloCloud SD-WAN. He tried to be positive, but for whatever reason this particular bit caught my interest:

Edge Gateways have a limited number of tunnels they can support […]

WTF? Wasn’t x86-based software packet forwarding supposed to bring infinite resources and nirvana? How badly written must your solution be to have a limited number of IPsec tunnels on a decent x86 CPU?

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Fast Linux Packet Forwarding with Thomas Graf on Software Gone Wild

We did several podcasts describing how one could get stellar packet forwarding performance on x86 servers reimplementing the whole forwarding stack outside of kernel (Snabb Switch) or bypassing the Linux kernel and moving the packet processing into userspace (PF_Ring).

Now let’s see if it’s possible to improve the Linux kernel forwarding performance. Thomas Graf, one of the authors of Cilium claims it can be done and explained the intricate details in Episode 64 of Software Gone Wild.

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Sometimes It’s Not the Network

Marek Majkowski published an awesome real-life story on CloudFlare blog: users experienced occasional short-term sluggish performance and while everything pointed to a network problem, it turned out to be a garbage collection problem in Linux kernel.

Takeaway: It might not be the network's fault.

Also: How many people would be able to troubleshoot that problem and fix it? Technology is becoming way too complex, and I don’t think software-defined-whatever is the answer.

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Is Flow-Based Forwarding Just Marketing Fluff?

When writing the Packet- and Flow-Based Forwarding blog post, I tried to find a good definition of flow-based forwarding (and I was not the only one being confused), and the one from Junos SRX documentation is as good as anything else I found, so let’s use it.

TL&DR: Flow-based forwarding is a valid technical concept. However, when mentioned together with OpenFlow, it’s mostly marketing fluff.

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Can Virtual Routers Compete with Physical Hardware?

One of the participants of the Carrier Ethernet LinkedIn group asked a great question:

When we install a virtual-router of any vendor over an ordinary sever (having general-purpose microprocessor), can it really compete with a physical-router having ASICs, Network Processors…?

Short answer: No … and here’s my longer answer (cross-posted to my blog because not all of my readers participate in that group).

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