Russ

Author Archives: Russ

It’s not a CLOS, it’s a Clos

Way back in the day, when telephone lines were first being installed, running the physical infrastructure was quite expensive. The first attempt to maximize the infrastructure was the party line. In modern terms, the party line is just an Ethernet segment for the telephone. Anyone can pick up and talk to anyone else who happens to be listening. In order to schedule things, a user could contact an operator, who could then “ring” the appropriate phone to signal another user to “pick up.” CSMA/CA, in essence, with a human scheduler.

This proved to be somewhat unacceptable to everyone other than various intelligence agencies, so the operator’s position was “upgraded.” A line was run to each structure (house or business) and terminated at a switchboard. Each line terminated into a jack, and patch cables were supplied to the operator, who could then connect two telephone lines by inserting a jumper cable between the appropriate jacks.

An important concept: this kind of operator driven system is nonblocking. If Joe calls Susan, then Joe and Susan cannot also talk to someone other than one another for the duration of their call. If Joe’s line is tied up, when someone tries to Continue reading

Reaction: Overly Attached

In a recent edition of ACM Queue, Kate Matsudaira has an article discussing the problem of being overly attached to a project or solution.

The longer you work on one system or application, the deeper the attachment. For years you have been investing in it—adding new features, updating functionality, fixing bugs and corner cases, polishing, and refactoring. If the product serves a need, you likely reap satisfaction for a job well done (and maybe you even received some raises or promotions as a result of your great work).

Attachment is a two-edged sword—without some form of attachment, it seems there is no way to have pride in your work. On the other hand, attachment leads to poorly designed solutions. For instance, we all know the hyper-certified person who knows every in and out of a particular vendor’s solution, and hence solves every problem in terms of that vendor’s products. Or the person who knows a particular network automation system and, as a result, solves every problem through automation.

The most pernicious forms of attachment in the network engineering world are to a single technology or vendor. One of the cycles I have seen play out many times across the last Continue reading

When should you use IPv6 PA space?

I was reading RFC8475 this week, which describes some IPv6 multihoming ‘net connection solutions. This set me to thinking about when you should uses IPv6 PA space. To begin, it’s useful to review the concept of IPv6 PI and PA space.

PI, or provider independent, space, is assigned by a regional routing registry to network operators who can show they need an address space that is not tied to a service provider. These requirements generally involve having a specific number of hosts, showing growth in the number of IPv6 addresses used over time, and other factors which depend on the regional registry providing the address space. PA, or provider assigned, IPv6 addresses can be assigned by a provider from their PI pool to an operator to which they are providing connectivity service.

There are two main differences between these two kinds of addresses. PI space is portable, which means the operator can take the address space when them when they change providers. PI space is also fixed; it is (generally) safe to use PI space as you might private or other IP address spaces; you can assign them to individual subnets, hosts, etc., and count on them remaining the Continue reading

History of the Internet: An Asian Perspective

Fun fact from this episode of the History of Networking: because of export rules, students in South Korea had to rebuild the TCP/IP stack for the PDP11 and other hosts in order to bring the first IP link up in southeastern Asia. In this recording, Donald and I are joined by Kilnam Chon.

Outro Music:
Danger Storm Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0 License
http://creativecommons.org/licenses/by/3.0/

The BGP Monitoring Protocol (BMP)

If you run connections to the ‘net at any scale, even if you are an “enterprise” (still a jinxed term, IMHO), you will quickly find it would be very useful to have a time series record of the changes in BGP at your edge. Even if you are an “enterprise,” knowing what changes have taken place in the routes your providers have advertised to you can make a big difference in tracking down an application performance issue, or knowing just when a particular service went off line. Getting this kind of information, however, can be difficult.

BGP is often overloaded for use in data center fabrics, as well (though I look forward to the day when the link state alternatives to this are available, so we can stop using BGP this way). Getting a time series view of BGP updates in a fabric is often crucial to understanding how the fabric converges, and how routing convergence events correlate to application issues.

One solution is to set up the BGP Monitoring Protocol (BMP—an abbreviation within an abbreviation, in the finest engineering tradition).

BMP is described in RFC7854 as a protocol intended to “provide a convenient interface for obtaining route views.” Continue reading

meeting madness, ONUG, and software defined

Jordan, Eyvonne, and I sit down for a conversation that begins with meetings, and ends with talking about software defined everything (including meetings??).

Outro Music:
Danger Storm Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0 License
http://creativecommons.org/licenses/by/3.0/

Weekend Reads 051919

Another week, another devastating, industry-shaking, cybersecurity threat. This week’s is particularly haunting, though — the resurrected corpse of the Spectre and Meltdown vulnerabilities, aptly known as ZombieLoad. —Another week, another devastating, industry-shaking, cybersecurity threat. This week’s is particularly haunting, though — the resurrected corpse of the Spectre and Meltdown vulnerabilities, aptly known as ZombieLoad.

Today sees the publication of a range of closely related flaws named variously RIDL, Fallout, ZombieLoad, or Microarchitectural Data Sampling. The many names are a consequence of the several groups that discovered the different flaws. From the computer science department of Vrije Universiteit Amsterdam and Helmholtz Center for Information Security, we have “Rogue In-Flight Data Load.” —Peter Bright

Academic researchers today disclosed details of the newest class of speculative execution side-channel vulnerabilities in Intel processors that impacts all modern chips, including the chips used in Apple devices. —Swati Khandelwal

Researchers have discovered a severe vulnerability in Cisco products that could allow attackers to implant persistent backdoor on wide range devices used in enterprises and government networks, including routers, switches, and firewalls. —Mohit Kumar

Intel’s struggles to get its 10 nanometer processors out the door has forced the company to do some serious soul-searching. And while Continue reading

History of Networking: Pseudowires

In this episode of the History of Networking, Donald Sharp and I talk to Luca Martini about the origins of pseudowires—one of the more interesting innovations in the use of MPLS.

Outro Music:
Danger Storm Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0 License
http://creativecommons.org/licenses/by/3.0/

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