A song that’s constantly whirring around in my head at the minute!
Enjoy!
Author Archives: jgreig
Daisywholesale / Murphx
Looks like daisywholesale / Murphx may be having some intermittent routing issues with some customers unable to reach the likes of the BBC website. Will keep you updated.
Jay Greig
Update: “Daisy Wholesale have detected a suspected line card fault at one of our datacentres, customers may be experiencing network routing issues. ” on the 20th September 2012 at 09:20 and is still ongoing
Plesk 10 and 11 Scheduled Tasks
I came across an issue recently with plesk control panel not playing ball with scheduled tasks / cron jobs. Since version 10, plesk places all users into a chroot in their home directory when performing tasks such as cron jobs. The problem with this is that when customers follow the guides of their CMS or any other application by them entering something like the following:
‘/usr/bin/php /var/www/vhosts/site.com/httpdocs/cron.php
They will find that the above fails miserably no matter how hard they try, ‘wget’, ‘curl’ no matter what as below:
/usr/bin/php: No such file or directory
/usr/bin/wget: No such file or directory
/usr/bin/curl: No such file or directory
Reason for this is that each user has a chroot with a number of binaries available to them in ‘/var/www/vhosts/site.com/bin’ and you’ll find there’s no ‘php’ binary in there. One method around this is to link php into the chroot but an easier way if you do not need the chroot is to switch things back to how they were by running the following on the server:
/usr/local/psa/bin/server_pref -u -crontab-secure-shell “/bin/sh”
This will tell the plesk built-in scheduler / cron handler to use normal /bin/sh allowing references to ‘/usr/bin/php’ to work.
Hope this helps people!
Jay Greig
CLI-MSN & DMitry CVS and Committers
I’ll shortly be looking at making the cvs repo available for CLIMSN and DMitry to open things up a little with the two projects. They’ve been gathering dust for quite a while and it would be nice to clean them up a bit. Any committers to the two projects are welcome as I’m not always able to dedicated my time to them both so drop me a line if you’re interested.
Jay Greig
3Com Access Layer Switching
I’ve always had a soft spot for 3com in a way with cost effective campus level switching i.e. (it’s cheap but has some fancy quirks!).
The original 3Com SuperStack series (which is obviously no more since the take over by HP) was a good series line offering feasible access layer for top of rack switching. I sound like a salesman here? The main requirements I’ve always had from them is ingress based traffic queueing/shaping at port level (not ACL based), dot1q vlans and snmp writing ability. From an automation point of view SNMP within a data centre can be crucial giving automated panels and front ends a ‘common’ communication path to access switches.
Over time i’ve seen a lot of the 4400 series which proved to be solid and stable for many years but more recently on a more negative note they seem to die of death with the main issue being when their management interfaces seem to stop responding to ARP requests and you can no longer reach them or communicate with them in any shape, way or form. It’s not a common fault i’ve found from the internet but i’ve seen plenty to conclude that it must be, in most cases a simple power on/off seems to resolve it but after a while this act in turn takes its toll on the device and will eventually call it a day with corrupt boot ups.
What can we conclude from this, well, switches 99% of the time are stable and reliable but with expanding networks, increased traffic (especially broadcast) issues are going to arise – if it’s not broke don’t fix it. In my line of work whenever we’ve seen 3coms showing signs of this behaviour we immediately recommend Cisco or similar as a replacement – specifically the 2960 series.
Xconnects on SVIs part 2
Following on from my previous post I found that in some instances it was either not practical or not possible down to the feature set of the IOS being run to successfully terminate xconnects on subinterfaces and have them actually pass traffic despite coming up.
Another workaround if you do want to achieve an alternative to terminating an xconnect on an SVI is to use portchannels (etherchannel). By terminating an xconnect on a port channel you can then place up to 8 ports into a channel group for example:
#interface Port-channel100 #no ip address #xconnect 92.60.104.41 1003 encapsulation mpls #! #interface GigabitEthernet3/3 #description XC: Backup servers #no ip address #channel-group 100 mode on #!
Ensuring that your ports are ‘no shut’ then you should find that running the following will show the link as up and you should be passing traffic:
#do sh mpls l2t vc
Local intf Local circuit Dest address VC ID Status
------------- -------------------- --------------- ---------- ----------
Gi3/2 Ethernet 92.60.104.34 1002 UP
Gi3/1 Ethernet 92.60.104.37 1001 UP
Po100 Ethernet 92.60.104.41 1003 UP
Now time to call it a day:)
James Greig
Xconnects on SVIs
Ever gone to try and terminate a cisco L2TPv3 xconnect on an SVI on Cisco 6500 and wondered why the hell it wouldn’t come up? You run the following:
switch# sh mpl l2transport vc
and find that the output is always down no matter what. Well, cleverly Cisco decided you’re not allowed to do that. A useful technology introduced to improve things actually ends up making things a little more difficult. It *is* possible if you have a SIP line card (ES20) for example, but if you’re reading this it’s doubtful you have one of these.
There is a possible workaround to achieve what you’re probably after. Although you cannot terminate the xconnect on an SVI you can, however, terminate the xconnect on a sub interface and in turn sub interface’s can be placed into a vlan. It’s not an ideal work around and in some cases it’s probably not very practical – nonetheless it is a sometimes feasible workaround if required. All that you should need to do is create a sub interface on the upstream facing link with the xconnect configuration and place the sub interface into a dot1q vlan – et voila
Hope this helps people:)
Also see the follow up article for another workaround: Xconnects on SVIs Part 2
James Greig
Hello
Hello all,
I’ve no idea why really but i’ve decided to setup wordpress on this site. The original content and open source projects will be here again soon, the server we had was flakey at the best of times so bare with me on that.
What i’m aiming to do is open this site for technical posting really. I work for an ISP and over the past 6 years I often come across challenges and as a natural born problem solver I wish to share some of what I’ve come to appreciate when building a reliable service.
I’ve a lot of work to do on the site especially as I have no idea about wordpress. In my line of work the only things I seem to ever hear are that someone’s wordpress has been hacked so maybe this isn’t the best choice, but, lets face it I’m even less motivated to build a new site from scratch at the moment:)
Check in again soon:)…. Now, how do I publish this….
J Greig