I’m currently testing & tweaking an iSCSI setup that utilises a Dell 6224 switch. These are very fast switches for the money (about ~£900 if you’ve got a good account manager!) and provide a lot of features, including stacking, if you have more than one. Their drawbacks, however, are mostly in the lack of documentation and/or the same level of user interface ‘polish’ that you receive from other manufacturers. Most people will say; ‘you get what you pay for’, but for the most part they are great switches for the money you pay.

One such “lack of documentation” has had me annoyed today. I’ve been using LACP to bond ports and, at the same time, have raised the MTU to the maximum of 9216 (which can be done per-port, without a reboot or a switchport up/down event, I might add) across all ports. All this, in an attempt to glean a little more performance (i.e. lower processing overhead) from my iSCSI sessions.

And it seemed to work just fine. However, upon inspecting the interface counters, I noticed a stunning amount of packets being regarded as ‘Oversize Packets’:


switch#show interfaces counters port-channel 1
Alignment Errors: ............................. 0
FCS Errors: ................................... 0
Single Collision Frames: ...................... 0
Multiple Collision Frames: .................... 0
Late Collisions: .............................. 0
Excessive Collisions: ......................... 0
Oversize Packets: ............................. 15829678
Internal MAC Rx Errors: ....................... 0
Received Pause Frames: ........................ 0
Transmitted Pause Frames: ..................... 0

I wasn’t sure whether or not to take this as an error or just a simple ‘count’ of packets. “Oversize” would indicate that they’re bigger than the port was expecting, but I was still hitting around 120MB/sec (out of the theoretical 125MB/sec that Gigabit Ethernet can physically provide) which wouldn’t be conducive to a serious string of frame/packet errors.

I couldn’t find anything online, so I contacted Dell ProSupport to raise a ticket. I had to go through the annoying rigmarole of explaining the problem three times over, but eventually a ‘switch expert’ explained that he wasn’t certain on the use of that counter and that its purpose depended on the firmware version currently in use (in my case, this was 3.2.0.9) and needed to check with his colleagues.

He eventually rang back to inform me that this was not a problem with the switch. The “Oversize Packets” counter merely serves to log packets that have a payload in excess of 1518 bytes. A fixed amount. It doesn’t matter than the MTU was set to 9216, it just continues counting the packets. Utterly useless, then!

As some form of consolation, he also mentioned that it didn’t update in real time.. Owing me to believe that there was some form of port stats analysing process running over the real time output. When it’s this useless, could I please have an option to turn it off? Or better yet, don’t bother logging it by default!

Today I’ve been informed (by my darling girlfriend) that her buddy icon was out of date: she’d changed it a while back, yet my client was appeared to be stubbornly displaying the old icon, even weeks later. As I couldn’t find a method for forcing the buddy icon to update within the program itself, I navigated to ~/.purple/icons (finding approximately 1,660 cached icons!) and deleted the lot.

Since restarting pidgin it’s taken a while for the buddy icons to repopulate for some reason, but after a few tests, it does appear that they’re updating properly when changed by the other party. As a side effect, I believe I’ve found (and fixed) the cause of pidgin’s leak/loop/error! Hopefully someone else will find my serendipitous bug-squashing useful.

I may even launch a bug report, given that I couldn’t find one. Now all I need is time to do so…

You could regard this as a possibly moronic statement at first, but there’s a little evidence to back it up. Firstly, I’ve been using the ‘adobe-flashplugin’ package provided via the Canonical Partner repository for some time. I think it works a heck of a lot better than Flash 9, and I’ve been much happier with the experience. That isn’t to say that it’s perfect, but at least Firefox doesn’t crash with every 3rd/4th Youtube video I play.

By standard of course, the Canonical Partner repository is disabled within a fresh Ubuntu installation. So when my girlfriend mentioned that the videos on Llewtube.com weren’t displaying, I wasn’t surprised to find that she was using the latest version of the ‘flashplugin-nonfree’ package:

sudo dpkg -l | grep flash
ii flashplugin-nonfree 10.0.22.87ubuntu1~intrepid1 Adobe Flash Player plugin installer

Given that I could view the videos on the aforementioned website without a single issue, I went to check my plugin version:

ii adobe-flashplugin 10.0.22.87-2intrepid1 Adobe Flash Player plugin version 10

So we’re supposedly using the same version of the Flash plugin, but from different packages. Would anyone like to explain why one package works and the other does not?

Getting around the problem was a simple task for her: simply enable the Partner repository by navigating to the Software Sources configuration utility (via System -> Administration -> Software Sources) and (after giving your password) checking the two ‘partner’ lines under the Third Party tab. If you don’t have them, you can add them (one at a time) with these two lines:

deb http://archive.canonical.com/ubuntu intrepid partner
deb-src http://archive.canonical.com/ubuntu intrepid partner

(If you’re reading this, and you’ve not yet upgraded to Ubuntu 8.10; the bulk of this guide should work with 8.04 also. You will, however, need to swap out ‘intrepid’ for ‘hardy’! )

When you’ve enabled the partner repositories (check the boxes) it’s a matter of closing Software Sources and letting it reload the package sources when prompted. After that, simply open a terminal and paste in the following:

sudo apt-get remove --purge flashplugin-nonfree && sudo apt-get install adobe-flashplugin

If you restart Firefox, you should now be sorted. If in doubt, search in Synaptic (System -> Administration -> Synaptic) for ‘Flash’ and see what is (or isn’t) installed.

I’ve spent the evening getting my RoutITX project off the ground and into service. But to do this, I needed an ADSL2+ modem. So, rather than persist with using my Netgear DB834GT, I thought I’d try out a P660R-D1 from Zyxel. Simple little thing, only about £25, and claims to be able to do bridging to its (single) Ethernet port.

Can it hell. I’ve tried everything I can; it can sync the DSL to a lovely speed, but it can’t get any further than that.

What I’d like is a nice, small, cheap, ADSL2+ modem (preferably including Annex M) that does a perfect bridge, with good reliability and performance.

There’s got to be one out there? I’d love to know.