The World’s Longest Console Cable – Smartflex Router Series


As everybody knows, console cables and their corresponding interfaces are a scourge on a network administrators existence. They are always too short, COM-ports get renumbered, Baud-rates are unknown, etc. By their very nature, you also have to be physically present in the vicinity of the box you’re trying to configure. Today we’re going to change all that, by constructing a wireless console cable adaptor with almost infinite range.

I can almost here people shouting something about SSH and Telnet to their screens, as well as something about the Airconsole. First and foremost, telnet and SSH are both wonderful, after you’ve configured the device, but for initial setup, they sadly can’t be used. Airconsole is quite nice, and I use it almost daily, but it’s useful when you want to sit somewhere comfortable when configuring a device in the same room as you, not so much when you want to be comfortable on a beach half a world away from the offending device.

This we’re going to change today, with one device, the B+B SmartFlex router.

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Time Servers – GPS Antenna Placement

Night Sky


If you haven’t noticed already, I have something of a thing for everything time synchronization related. “Proper”, exact time is something that I find important, it’s probably OCD related.
As a part of my day job, I manage a quite large network, with hundreds of different devices. And all of these require some method to synchronize their clocks. Anyone who has at some point tried to diagnose a network problem knows how absolutely critical it is to have proper time available at the devices, so that you for example have any chance to compare logs etc.

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How to Stack HPE/Aruba 2920 Switches – HP Networking Series Part 4


The 2920 series switches from HPE/Aruba has a special feature that no other switches in the old ProCurve/E-Series line-up has; dedicated stacking interfaces. On other HPE switches, stacking merely facilitates “simplified” management, by allowing you to manage any switch in the stack from the stack commander’s CLI. On the 2920 series however, you can use dedicated stacking interfacing, giving you 2 20 Gbps links to other switches in the stack and merging two to four switches into one coherent switch. This is quite similar on how stacking works on some Cisco models, but the specialized stacking interfaces gives you higher speeds between the members. In this article, I’ll show you have to set up the commander switch and how to add switches to the stack once it’s created. I’ll also go into how it affects the configuration of the switches, which is quite crucial if you want to stack switches that are already in production.

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Cisco Switch Not Responding to Ping? – Cisco Networking Series Part 2

No Response?

If you’re anything like me, you like to get things up and running fast. And this means doing a bare minimum configuration of a new switch so you can get to testing connectivity as soon as possible.

So, what do you do? You boot the switch, give it a hostname and a some basic security settings, and then you configure the management VLAN and give it an IP address. After that you configure the trunk interface and try pinging the switch from another device. And everything fails. And you tear out your hair trying to figure out what’s wrong. And finally, after what feels like a lifetime (in reality about 2 minutes), you try pinging something else in the network from the new switch. And it works perfectly.

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Setting up NTP on Cisco Switches – Cisco Networking Series Part 1


This is more for my own reference than anything else, but what follows here is a short tutorial on how to get NTP up and running on your Cisco iOS device.

First we need to get DNS working for the switch to be able to resolve the DNS name for the time server. If you run your own time server you can use the static IP for the NTP server and skip this step, but if you use one of the public NTP pools just resolving the domain name for the pool one time and hard coding that into your switch won’t do it. First of all, that NTP server might go down some time down the line, and then your time synchronization stops working. Secondly, and this is actually a far bigger problem, if you resolve the IP of a NTP pool, you’re actually only using one server in that pool constantly since the pools load balancing is constructed using DNS round robin. This skews the load on the (already heavily loaded) public NTP infrastructure, which isn’t very good. While we’re on the topic, if you are using public NTP servers, consider setting up your own internal NTP servers and have your clients sync to them, thus limiting the load you put on public NTP servers. If you, like me, run your own GPS NTP servers, then you can do as you like (but the DNS round robin trick is also useful to do internal load balancing and fail-over)

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Setting up NTP on HP Switches – HP Networking Series Part 3

This is a short guide on how to set up NTP time synchronisation on HP Network devices. I’ll be covering SNTP settings in this guide, as well as some of the niftier things that aren’t in the manuals but still are really handy. NTP time synchronisation allows you to maintain correct time across your network, which is very important for troubleshooting when comparing logs between two switches for example.

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Using the reload command with HP Switches – HP Networking Series Part 2

When configuring network hardware over the network itself it’s very easy to issue a command that breaks the network connection to the switch, requiring you to visit the switch and connect to it with a console cable to fix the issue. This is not a big problem if the switch is just down the hall in a closet somewhere, but in today’s world a switch that you’re configuring might be hundred of miles away from where you’re sitting.

Of course this whole issue can be sidestepped by just thinking through what you’re doing before hitting the enter key, but in the real world this is not always an available luxury.

The solution to this problem is to cleverly utilize the “reload” command in combination with the “write” command.

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How to set up STP on HP Switches – HP Networking Series Part 1

Setting up Spanning Tree on HP switches is really easy, after you’ve done it a couple of times, but getting it configured can seem like a daunting task for beginners, espcially in a production network. Here are some simple steps on how to get it up and running in no time. Note that enabling STP might cause small network outages, so don’t do this in a production network if you haven’t tried it before! All commands are written within “citation”-marks, so that’s what you need to enter into the CLI on your switch. For completeness I’ve added all the commands in order at the bottom of the post, which might be handy if you’re just looking for a CLI-reference.

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Professional Rack Installation = 8 Hours of Labeling

DELL Server im Rack

Originally uploaded by BlaM4c

Last week I spent close to 8 hours printing and applying labels to different cables in a packed and live rack. And it didn’t help that the rack runs our virtual servers, ie. our most mission critical servers.
The rack itself consists of 3 identical 1U servers from Dell, 2 Gigabit Dell switches trunk’d into each other running separate VLANs for iSCSI and “normal” traffic. The EqualLogic HDD-array that provides the storage for the servers runs 2 controllers, both with a connection to both switches. Then there’s 5 CAT6 cables for each server providing the iSCSI, server management, virtual server NIC etc.

All in all I think I labeled 5 cables per server (15), 3 per EqualLogic module (6), 3 iSCSI cables for some other servers and 2 trunk cables. In both ends. So if my math is correct, that amounts to 30+12+6+4= 52 labels on just network cables. Then the servers needed 2 labels each (6), the EQ-box plus labels identifying the controller modules (3), the 2 UPSs and the 2 switches. That’s 13 more labels. So all in all I did over 65 labels that day.

Now, I’m perfectly clear on why this rack needs labels just about everywhere. Imagine on cable comes loose when you’re fiddling with something. Then if that cable end is labeled with which port it goes into, then reconnecting it correctly becomes a very minor task, and can be done quite swiftly.

The problem I had with this task is that the week before, 2 technicians from Dell spent the whole week setting up the rack. It would have been a lot easier for everyone if they’d bothered labeling every cable as it went into the rack in the first place instead of me carefully tracing each and every cable in the operational rack.

More Bloody Printers

Today I got into another argument with a network printer. I installed a new computer at a remote location, and they had their own Samsung network printer that I had to connect manually.

Most people that aren’t familiar with Samsungs can’t probably understand why this would be a problem, just go into printers, do a network search, and add the thing. This is indeed the correct procedure for standard network printer, like a Canon for instance, but not for Samsungs.

The last Samsung I had to install was pretty complicated as well, it didn’t show up in the network listings, as that particular model didn’t use IP-addresses but some weird UDP broadcast system that you needed a special “admin” tool to find and configure, both when installing the printer and when installing them for the user. This one, however, was a bit different.

This blasted thing has it’s own IP address, but, when you go to install it, it just smiles at you for 5 minutes and then Windows complains that it can’t connect to the printer. And as I didn’t remember the awkwardness of installing the last one, I spent the next 15-30 minutes troubleshooting the network connections, which consisted mainly of loose handmade network cables (remember my last post?).

Anyhow, finally, after checking cables and other network gear, I remembered the other printer and downloaded the drivers. I tried installing them on the user account by selecting “Run as…” instead of running it under my account, which resulted in the installer freezing 10 minutes in when it called some other part that tried to run without admin privileges (they probably didn’t think of programming in a fail safe or making sure the other process inherited the privileges of the first one). This got me even more frustrated (this all happened just before lunch time) as I hate having to install printer software under the admin account just to find out it doesn’t add the printer for the users and it won’t work to install them there either, then you need to upgrade the user to admin for a while and it’s just such a PITA.

Anyhow, after installing the blasted thing under my admin account, it finally worked, and miracle of all miracles, the installer added the printer for all users, be they domain or local.

So, the point of my endless rant is that why can’t some manufacturers make TCP/IP printers that can be added through the Windows dialogues, when some apparently can, and WHY do they choose these insanely complicated workaround tools for this? I can understand it when it’s one of these UDP machines I’m dealing with, as there’s an actual need for that tool, and it’s quite handy as well (try upgrading a server shared printer with a fixed IP to a static IP from the DHCP and you’ll see what I mean), but WHY OH WHY do they do it with the ones that use TCP?