Russ

Author Archives: Russ

Leave Your Ego at the Door

You are just about to walk into the interview room. Regardless of whether you are being interviewed, or interviewing—what are you thinking about? Are you thinking about winning? Are you thinking about whining? Or are you thinking about engaging? I have noticed, on many mailing lists, and in many other forums, that interviews in our world have devolved into a contest of egos.

The person on the other side of the table has some certification I don’t care about—how can I prove they are dumb, not as smart as their certification might indicate, or… The person on the other side of the table claims to know some protocol, can I find some bit of information they don’t know? These kinds of questions are really just ego questions—and you need to leave them at the door. This is particularly acute with certifications right now—a lot of people doubt the value of certifications, claiming folks who have them don’t know anything, the certifications are worthless, they don’t reflect the real world, etc.

I will agree that we have a problem with the depth and level of knowledge of network engineers at the moment. We all need to grow up a little, learn Continue reading

Upcoming Webinar: Open Networking for Large Scale Networks

Shawn Zandi and I are doing a two part webinar over at ipspace.net—

Most modern data centers are still using vendor-driven “future proof” routers and switches with offering lots of (often unnecessary) capabilities. To build large, however, it is often better to build simple—radically simple. This webinar will cover the design components involved in building a data center or cloud fabric using a single, disaggregated device—the way some hyperscale and web scale operators build their networks. The first live session of the webinar will consider the benefits of disaggregated switch, focusing on the components, sources, and challenges in using disaggregated hardware and software in data center fabrics. The second live session will focus on the topologies and design concepts used in large scale data center fabrics using a single switching device as a leaf, spine and superspine switch.

Jump over to ipspace if you want to learn more.

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Mitigating DDoS

Your first line of defense to any DDoS, at least on the network side, should be to disperse the traffic across as many resources as you can. Basic math implies that if you have fifteen entry points, and each entry point is capable of supporting 10g of traffic, then you should be able to simply absorb a 100g DDoS attack while still leaving 50g of overhead for real traffic (assuming perfect efficiency, of course—YMMV). Dispersing a DDoS in this way may impact performance—but taking bandwidth and resources down is almost always the wrong way to react to a DDoS attack.

But what if you cannot, for some reason, disperse the attack? Maybe you only have two edge connections, or if the size of the DDoS is larger than your total edge bandwidth combined? It is typically difficult to mitigate a DDoS attack, but there is an escalating chain of actions you can take that often prove useful. Let’s deal with local mitigation techniques first, and then consider some fancier methods.

  • TCP SYN filtering: A lot of DDoS attacks rely on exhausting TCP open resources. If all inbound TCP sessions can be terminated in a proxy (such as a load balancer), Continue reading

RTGWG Interim Meeting on Data Center Challenges

Last week, the Routing Area Working Group (IETF) held an interim meeting on challenges and (potential) solutions to large scale data center fabric design. I’ve filed this here because I spoke for all of about 3 minutes out of the entire meeting—but I really wanted to highlight this meeting, as it will be of interest to just about every network engineer “out there” who deals with data center design at all.

There are three key URLs for the interim

The agenda
The session slides and links to drafts presented
A Webex recording of the entire proceedings

My reaction, in general, is that we are starting to really understand the challenges in a networking way, rather than just as a coding problem, or a “wow, that’s really big.” I’m not certain we are heading down the right path in all areas; I am becoming more convinced than ever that the true path to scale is to layer the control plane in ways we are not doing today. You can see this in the LinkedIn presentation, which Shawn and I shared. I tend to think the move towards sucking every bit of state possible out of the control plane is a Continue reading