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The First Bufferbloat Battle Won

Bufferbloat was covered in a number of sessions at the Vancouver IETF last week.

The most important of these sessions is a great explanation of Kathie Nichols and Van Jacobson’s CoDel (“coddle”) algorithm given during Tuesday’s transport area meeting by Van.  It is not to be missed by serious network engineers. It also touches on why we like fq_codel so much, though I plan to write much more extensively on this topic very soon. CoDel by itself is great, but in combination with SFQ (like) algorithms that segregate flows, the results are stunning; CoDel is the first AQM algorithm which can work across arbitrary number of queues/flows.

The Saturday before the IETF the IAB / IRTF Workshop on Congestion Control for Interactive Real-Time Communication took place. My position paper was my blog entry of several weeks back. In short,  there is no single bullet, though with CoDel we finally have the final missing bullet for its complete solution. The other, equally important but non-technical bullets will be market pressure fix broken software/firmware/hardware all over the Internet: so exposing the bloat problem is vital. You cannot successfully engineer around bufferbloat, but you can detect it, and let users know when they Continue reading

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How does Openflow, SDN help Virtualization/Cloud (Part 3 of 3) – Why Nicira had to do a deal?

The challenges faced by Openflow and SDN

This is the 3rd and final article in this series. As promised, lets look at some of the challenges facing this space and how we are addressing those challenges.

Challenge 1 – Which is why Nicira had to get a big partner

I have seen a lot of article about Nicira being acquired. The question no one has asked is – if the space is so hot, why did Nicira sell so early? The deal size (1.26B) was hardly chump change but if I were them and my stock was rising exponentially, then I would have held off in lure of changing the world. So what was the rush? I believe the answer lies in some of the issues I discussed in article 2 of this series a few months back–the difference between server (Controller-based) and switch (Fabric-based) approaches. The Nicira solution was very dependent on the server and the server hypervisor. The world of server operating systems and hypervisor is so fragmented that staying independent would have been a very uphill battle. Tying up with one of the biggest hypervisors made sense to ensure that their technology keeps moving forward. And Continue reading

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The IPv6 DFZ just passed 10.000 prefixes

I noticed the IPv6 Default Free Zone just tipped over 10.000 prefixes. I think this is quite a milestone! Go IPv6!

The data was taken from the RING Looking Glass, which is part of the NLNOG RING project. The RING Looking Glass takes full BGP feeds from ± 20 organisations.

BTW, as an apples and peaches comparison: the IPv4 full routing table currently is roughly 415.000 prefixes. Live IPv4 and IPv6 graphs can be viewed here (RING) and here (Potaroo).

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Native VLAN – Some Surprising Results

I did some fiddling around with router-on-a-stick configurations recently and found some native VLAN behavior that took me by surprise.

Dead Simple Routers-On-A-Stick Configuration

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KICLet: Solarwinds’ Dirty Google Tricks

This is a (justifiable) rant. You’ve been warned. Solarwinds Orion NPM is an okay tool, but when it comes to managing anything other than Cisco switches and routers, it’s…..meh. It takes very little effort to get devices like that monitored to the fullest extent, but when it comes to something like a storage array, it seems like you really have to make tweaks until your fingers bleed to get the minimal monitoring functionality out of it.

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KICLet: Solarwinds’ Dirty Google Tricks

This is a (justifiable) rant. You’ve been warned. Solarwinds Orion NPM is an okay tool, but when it comes to managing anything other than Cisco switches and routers, it’s…..meh. It takes very little effort to get devices like that monitored to the fullest extent, but when it comes to something like a storage array, it seems like you really have to make tweaks until your fingers bleed to get the minimal monitoring functionality out of it.

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Doing Etherchannel Over 3, 5, 6, and 7 Link Bundles

As a follow-up to my previous article on Port Channels titled “4 Types of Port Channels and When They're Used” I wanted to talk a bit about the long-standing rule that says you should always create your Etherchannel (EC) bundles with a number of links that works out to a power of two (ie, 2,4 or 8 links). That rule is less applicable today than it used to be.

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New 10Gb/s Interconnect Options

Followers of this blog, or folks who've heard me on the Packet Pushers Podcast may have noticed that I obsessively look for less expensive ways to interconnect data center devices.

That's because the modules are so expensive! A loaded Nexus 7010 is intimidating enough with it's $473,000 list price, but that's without any optic modules...

If we want to link those interfaces to something with 10GBASE SR modules then triple the budget because the optics cost twice as much as the switch:

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4 Types of Port Channels and When They’re Used

The other day I was catching up on recorded content from Cisco Live! and I saw mention of yet another implementation of port channels (this time called Enhanced Virtual Port Channels). I thought it would make a good blog entry to describe the differences of each, where they are used, and what platforms each is supported on.

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Beware of IPv6 Transition Techniques as Endgame

By now, even the non-technical folks out there are aware of IPv4 address exhaustion (The IPocalype), thanks to the problem finally coming into the consciousness of the mainstream media. As organizations plan how to deal with this exhaustion, those who … Continue reading →

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Marathon Networks’ PVTD

I have seen many broken Private VLAN networks, and decided to find a way to fix them. So in the last year I have developed a network appliance called PVTD, which solves many of the Private VLAN problems. You can read all bout it at www.marathon-networks.com

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KIClet: Sub-Optimal Fibre Channel Path Selection

The SAN I’m currently working with connects a pair of Netapp FAS3270 filers running ONTAP 8.0.2 7-Mode. If you’re running VMware ESXi in your environment in front of a Fibre Channel SAN, path selection is discovered more or less in a first-come-first-served fashion. I got this message on my Netapp filer: FCP Partner Path Misconfigured: Host I/O access through a non-primary and non-optimal path was detected. Since the LUNs mounted by ESXi were residing on the A-side filer, the paths going through the B-side filer would just be sent over the partner link to the A-side, which is less efficient than going directly through A.

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KIClet: Sub-Optimal Fibre Channel Path Selection

The SAN I’m currently working with connects a pair of Netapp FAS3270 filers running ONTAP 8.0.2 7-Mode. If you’re running VMware ESXi in your environment in front of a Fibre Channel SAN, path selection is discovered more or less in a first-come-first-served fashion. I got this message on my Netapp filer: FCP Partner Path Misconfigured: Host I/O access through a non-primary and non-optimal path was detected. Since the LUNs mounted by ESXi were residing on the A-side filer, the paths going through the B-side filer would just be sent over the partner link to the A-side, which is less efficient than going directly through A.

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What is LISP DDT?

Some background on LISP

LISP (Locator/Identifier Separation Protocol) is a smart and novel method to create overlay networks with features such as multi-homing, mobility and VPN-segregation. These feats are possible because LISP makes a distinction between the 'who' and the 'where'.

"The separation of location and identity is a step which has recently been identified by the IRTF as a critically necessary evolutionary architectural step for the Internet."

- N. Chiappa in draft-chiappa-lisp-introduction-00 

An example would be that my IPv6 prefix 2001:67c:208c:10::/64 (the 'who') currently is located behind the following WAN IP addresses: 62.194.155.106, 217.8.107.2 and 2001:67C:21B4:1::2 (the 'where'). In this example my prefix is multi-homed behind 3 connections, and I'm doing IPv6 over IPv4 next to IPv6 over IPv6. This is possible because this single IPv6 prefix can have multiple Routing Locators (the 'where') and LISP is address-family agnostic.

Mapping systems for location information

As you can imagine, the key to protocols like LISP is locating who is where in a fast and efficient way.

To create more context: with the Border Gateway Protocol (BGP) all participating nodes (routers) have all information about everybody in memory. When an organisation Continue reading

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KIClet: Microphone troubles with Lenovo W520

I came across this the other day and wanted to share. For some reason, Windows by default decided to enable the “audio enhancements” feature on my new Lenovo Thinkpad w520. This caused my microphone to essentially be unusable - I was in several webex meetings and each time everyone said I was completely garbled and not even close to being able to understand me. After a little poking around, I found this:

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KIClet: Microphone troubles with Lenovo W520

I came across this the other day and wanted to share. For some reason, Windows by default decided to enable the “audio enhancements” feature on my new Lenovo Thinkpad w520. This caused my microphone to essentially be unusable - I was in several webex meetings and each time everyone said I was completely garbled and not even close to being able to understand me. After a little poking around, I found this:

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Get-Console Review on the iPad

I have used my iPad to console onto Cisco routers and switches for about 2 years now. I started using the Flex-Serial cable on my jailbroken iPad and iPhone, with the iSSH app and a ported version of Minicom (earlier blog post).  Amidst some minor bugs and irritations this worked well and was considerably more […]

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The Internet is Broken, and How to Fix It

Many real time applications such as VOIP, gaming,  teleconferencing, and performing music together, require low latency. These are increasingly unusable in today’s internet, and not because there is insufficient bandwidth, but that we’ve failed to look at the Internet as a end to end system. The edge of the Internet now often runs congested. When it does, bufferbloat causes performance to fall off a cliff.

Where once a home user’s Internet connection consisted of a single computer, it now consists of a dozen or more devices – smart phones, TV’s, Apple TV’s/Roku devices, tablet devices, home security equipment, and one or more computer per household member. More Internet connected devices are arriving every year, which often perform background activities without user’s intervention, inducing transients on the network. These devices need to effectively share the edge connection, in order to make each user happy. All can induce congestion and bufferbloat that baffle most Internet users.

The CoDel (“coddle”) AQM algorithm provides the “missing link” necessary for good TCP behavior and solving bufferbloat. But CoDel by itself is insufficient to solve provide reliable, predictable low latency performance in today’s Internet.

Bottlenecks are most common at the “edge” of the Internet and there you must Continue reading

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CCIE Security

I have just successfully passed the CCIE Security written exam at Cisco Live 2012. The exam was no cake walk and was very challenging. Although I studied all the material from the CCNP security track and read the Network Security Technologies and Solutions (CCIE Professional Development Series) book I did not take any of the CCNP Security exams. I took a little different approach to this CCIE then I took in the R&S track. I will be starting to do the practice labs and will go back to theory throughout the process to do each of the CCNP Security exams. I am hoping that this ensures that I perform the practice labs without fail and continue to cement the theory throughout the process.


Thoughts?

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IOS XR and the egrep function

As you may have already realised I am always looking for ways to speed up my day to day tasks. Every few days I check my BGP peering to see if there are any sessions down and then give the … Continue reading →