Russ
Author Archives: Russ
- Home → Author's archive:
Russ
Strong Reactions and Complexity
In the realm of network design—especially in the realm of security—we often react so strongly against a perceived threat, or so quickly to solve a perceived problem, that we fail to look for the tradeoffs. If you haven’t found the tradeoffs, you haven’t looked hard enough—or, as Dr. Little says, you have to ask what is gained and what is lost, rather than just what is gained. This failure to look at both sides often results in untold amounts of technical debt and complexity being dumped into network designs (and application implementations), causing outages and failures long after these decisions are made.
A 2018 paper on DDoS attacks, A First Joint Look at DoS Attacks and BGP Blackholing in the Wild provides a good example of causing more damage to an attack than the attack itself. Most networks are configured to allow the operator to quickly configure a remote triggered black hole (RTBH) using BGP. Most often, a community is attached to a BGP route that points the next-hop to a local discard route on each eBGP speaker. If used on the route advertising the destination of the attack—the service under attack—the result is the DDoS attack traffic no longer Continue reading
The Hedge Podcast #58: Michael Kehoe and eBPF
Most packet processing in Linux “wants” to be in the kernel. The problem is that adding code to the kernel is a painstaking process because a single line of bad code can cause havoc for millions of Linux hosts. How, then, can new functionality be pushed into the kernel, particularly for packet processing, with reduced risk? Enter eBPF, which allows functions to be inserted into the kernel through a sort of “lightweight container.”
Michael Kehoe joins Tom Ammon and Russ White to discuss eBPF technology and its importance.
The History of Networking: John Chapman and Cable Networks
Before the large cable providers came on the scene, most people accessed the Internet through dial-up MODEMS, connecting to services like America Online, across plain old telephone lines. The entrance of cable providers, and cable MODEMs, allowed the edge of the Internet to explode, causing massive growth. Join Donald Sharp and I on this episode of the History of Networking as John Chapman discusses the origins of the cable MODEM, and the origins of the DOCSIS standards.
Random Thoughts on IoT
Let’s play the analogy game. The Internet of Things (IoT) is probably going end up being like … a box of chocolates, because you never do know what you are going to get? a big bowl of spaghetti with a serious lack of meatballs? Whatever it is, the IoT should have network folks worried about security. There is, of course, the problem of IoT devices being attached to random places on the network, exfiltrating personal data back to a cloud server you don’t know anything about. Some of these devices might be rogue, of course, such as Raspberry Pi attached to some random place in the network. Others might be more conventional, such as those new exercise machines the company just brought into the gym that’s sending personal information in the clear to an outside service.
While there is research into how to tell the difference between IoT and “larger” devices, the reality is spoofing and blurred lines will likely make such classification difficult. What do you do with a virtual machine that looks like a Raspberry Pi running on a corporate laptop for completely legitimate reasons? Or what about the Raspberry Pi-like device that can run a fully operational Continue reading
This is totally random … The Art of Charity
I don’t normally do this, but … I’d like to share a couple of images of watercolors by a friend of mine. She really does do whimsical and impressive work. Links to her site off the images below.
The Hedge Podcast #57: Brian Trammell and PANRG
Brian Trammell joins Alvaro Retana and Russ White to discuss the Path Aware Research Group in the IRTF. According to the charter page, PANRG “aims to support research in bringing path awareness to transport and application layer protocols, and to bring research in this space to the attention of the Internet engineering and protocol design community.”
Technologies that Didn’t: Network Operating Systems
For those with a long memory—no, even longer than that—there were once things called Network Operating Systems (NOS’s). These were not the kinds of NOS’s we have today, like Cisco IOS Software, or Arista EOS, or even SONiC. Rather, these were designed for servers. The most common example was Novell’s Netware. These operating systems were the “bread and butter” of the networking world for many years. I was a Certified Netware Expert (CNE) version 4.0, and then 4.11, before I moved into the routing and switching world. I also deployed Banyan’s Vines, IBM’s OS/2, and a much simpler system called LANtastic, among others.
What were these pieces of software? They were largely built around providing a complete environment for the network user. These systems began with file sharing and directory services and included a small driver that would need to be installed on each host accessing the file share. This small driver was actually a network stack for a proprietary set of protocols. For Vines, this was VIP; for Netware, it was IPX. Over time, these systems began to include email, and then, as a natural outgrowth of file sharing and email, directory services. For some time, there Continue reading
Hints and Principles: Applied to Networks
While software design is not the same as network design, there is enough overlap for network designers to learn from software designers. A recent paper published by Butler Lampson, updating a paper he wrote in 1983, is a perfect illustration of this principle. The paper is caleld Hints and Principles for Computer System Design. I’m not going to write a full review here–you should really go read the paper for yourself–but rather just point out some useful bits of the paper.
The first really useful point of this paper is Lampson breaks down the entire field of software design into three basic questions: What, How, and When (or who)? Each of these corresponds to the goals, techniques, and processes used to design and develop software. These same questions and answers apply to network design–if you are missing one of these three areas, then you are probably missing some important set of questions you have not answered yet. Each of these is also represented by an acronym: what? is STEADY, how? is AID, and when? is ART. Let’s look at a couple of these in a little more detail to see how Lampson’s system works.
STEADY stands for simple, timely, efficient, Continue reading
Hedge Podcast #56: Lysa Myers on Burnout and Good People
PTSD is a real thing in the information technology world; it impacts the ability to keep and manage good people. In this episode of the Hedge, Lya Myers joins Eyvonne Sharp, Tom Ammon, and Russ White to discuss PTSD, burnout, and strategies for dealing with them.
History of Networking: Mark Nottingham and HTTP
The HyperText Transfer Protocol (HTTP) carries the vast majority of all the traffic on the Internet today, and even the vast majority of traffic carried on private networks. How did this protocol originate, and what was the interplay between standards organizations in it’s creation, curation, and widespread deployment? Mark Nottingham joins Donald and I on this episode of the History of Networking to answer our questions.
<em><a href=”https://historyofnetworking.s3.amazonaws.com/Mark-N_HTTP.mp3″>download</a></em>
Underhanded Code and Automation
So, software is eating the world—and you thought this was going to make things simpler, right? If you haven’t found the tradeoffs, you haven’t looked hard enough. I should trademark that or something! 
While a lot of folks are thinking about code quality and supply chain are common concerns, there are a lot of little “side trails” organizations do not tend to think about. One such was recently covered in a paper on underhanded code, which is code designed to pass a standard review which be used to harm the system later on. For instance, you might see at some spot—
if (buffer_size=REALLYLONGDECLAREDVARIABLENAMEHERE) {
/* do some stuff here */
} /* end of if */Can you spot what the problem might be? In C, the = is different than the ==. Which should it really be here? Even astute reviewers can easily miss this kind of detail—not least because it could be an intentional construction. Using a strongly typed language can help prevent this kind of thing, like Rust (listen to this episode of the Hedge for more information on Rust), but nothing beats having really good code formatting rules, even if they are apparently arbitrary, for catching Continue reading
Link State in DC Fabrics
If you don’t normally read IPJ, you should. Melchoir and I have an article up in the latest edition on link state in DC fabrics.
The Hedge Podcast #55: Nick Carter and Flock Networks
Nick Carter joins Tom and I to discuss Flock Networks. What is Flock Networks?
RFC1925 Rule 2
According to RFC1925, the second fundamental truth of networking is: No matter how hard you push and no matter what the priority, you can’t increase the speed of light.
However early in the world of network engineering this problem was first observed (see, for instance, Tanenbaum’s “station wagon example” in Computer Networks), human impatience is forever trying to overcome the limitations of the physical world, and push more data down the pipe than mother nature intended (or Shannon’s theory allows).
One attempt at solving this problem is the description of an infinitely fat pipe (helpfully called an “infan(t)”) described in RFC5984. While packets would still need to be clocked onto such a network, incurring serialization delay, the ability to clock an infinite number of packets onto the network at the same moment in time would represent a massive gain in a network’s ability, potentially reaching speeds faster than the speed of light. The authors of RFC5984 describe several attempts to build such a network, including black fiber, on which the lack of light implies data transmission. This is problematic, however, because a lack of information can be interpreted differently depending on the context. A pregnant pause has far different meaning Continue reading
Reducing Complexity through Interaction Surfaces
A recent paper on network control and management (which includes Jennifer Rexford on the author list—anything with Jennifer on the author list is worth reading) proposes a clean slate 4d approach to solving much of the complexity we encounter in modern networks. While the paper is interesting, it’s very unlikely we will ever see a clean slate design like the one described, not least because there will always be differences between what the proper splits are—what should go where.
There is one section of the paper that eloquently speaks to current architecture, however. The authors describe a situation where routing and packet filters are used together to prevent one set of hosts from reaching another set of hosts. Changes in the network, however, cause the packet filters to be bypassed, opening up communications between these two sets of hosts.
This is exactly the problem we so often face in network engineering today—overlapping systems used to solve a single problem do not pay attention to the same signals or information to do their jobs. So here’s a thought about an obvious way to reduce the complexity of your network—try to use one tool to do one job. Before the days of automation, this was much harder to do. There was no way to distribute QoS configurations, for instance, or access lists, much less what might be considered an “easy way.” Because of this, it made some kind of sense to use routing protocols as a sort of distributed database and policy engine to move filters and the like around.
Today, however, we have automation. Because of this, it makes more sense to use automation to manage as much data plane policy as you can, leaving the routing protocol to do its job—provide reachability across an ever-changing network. There are still things, like traffic steering and prefix distribution rules, which should stay inside routing. But when you put routing filters in place to solve a data plane problem, it might be worth thinking about whether that is the right thing to do any longer.
Automation, in this case, can change everything.