Thursday, March 20, 2014

Toshiba Mobile LCD and IE 10 or 11 crash

I have one user with a Toshiba Portege ultrabook, and it's been fine. He also wanted a Toshiba mobile LCD screen to bring along for more screen real estate. Eventually his machine started having issues with Internet Explorer, where IE would crash immediately upon opening. I assumed it was a corrupt IE install since IE 10 had just came out, but uninstalling/reinstalling IE 10 didn't help. IE 9 worked fine though. After going through plenty of additional troubleshooting I finally found the cause of the issue. It was the DisplayLink driver that was installed with the mobile LCD screen. When that driver was installed IE would stop working, and as soon as it was uninstalled IE would go back to normal. Luckily DisplayLink had newer drivers available to download, and the driver worked fine with both IE 10 and IE 11.

For anyone scratching your head trying to find a solution to IE 10 or 11 crashing, if you have a portable LCD screen in use that uses DisplayLink drivers, try updating those first. It'll save you plenty of head scratching and unnecessary malware scans.

Friday, March 14, 2014

Configure VLAN(s) and enable routing on an HP Procurve switch

If you're running a managed HP Procurve switch and want to take advantage of VLANs to subnet your network, it's pretty easy. Here's a diagram of my example

In this example we have two VLANs (VLAN 1 and VLAN 2). VLAN 2 is setup just for workstations and must connect to VLAN 1 for DHCP, DNS, and Internet access.

In case the image is too small, on the switch, ports 1-24 are being designated as part of VLAN 1, and 25-48 are part of VLAN 2. VLAN 1 is the subnet, and VLAN 2 is the subnet.

On my primary and secondary DNS/DHCP servers, I have a DHCP scope setup for the primary network (VLAN 1), and another scope setup for VLAN 2. In my DHCP options for both, I set the primary DNS server to, and the secondary to For VLAN 1, I set the router to, but on VLAN 2 I set the router to since the default gateway needs to be found within the same subnet.

To actually set this up, first, you would telnet into your Procurve switch, which I'm hoping you know how to do if you're going to attempt setting up a VLAN. You'll need enable access on the switch as well. Once you've logged into the switch and are at the terminal, here is what I would enter to set up the above example. I've added comments/explanations on all lines, so be aware that you do not want to enter the - (.....) from the lines into the terminal window

enable - (enables admin access)
conf t - (enters configuration mode using the terminal)
ip routing - (enabled IP-based routing, which is required to allow the two VLANs to communicate)
vlan 1 - (will enter the configuration mode for vlan 1, which should exist by default on the switch)
untag 1-24 - (untags ports 1-24 on the switch to indicate they're going to be restricted to vlan 1)
ip address - (assigns the IP address of to the VLAN 1 interface)
vlan 2 - (will create vlan 2 if it doesn't already exist, then enters configuration mode for it)
untag 25-48 - (untags ports 25-48 on the switch to indicate they're going to be restricted to vlan 2)
ip address - (assigns the IP address of to the VLAN 1 interface)
ip helper-address - (sets VLAN 2 to send DHCP packets to the primary DHCP server)
ip helper-address - (sets VLAN 2 to send DHCP packets to the secondary DHCP server)
ip route - (sets the default route to the default gateway in VLAN 1)
write mem - (commits the changes you made to the configuration stored in memory on the switch)
end - (exits configuration mode)
exit - (exits enable mode)
exit - (logs you off from your telnet session)

The one issue I ran into when I first did it is I had "ip default-gateway" set on my switch and thought that was good enough for my VLAN 2 to get to the Internet. However, that is only effective when ip routing is disabled, and for the VLANs to communicate ip routing needs to be turned on. That requires you to add an actual static route, or use ip default-network if it's an available option. For more information on that see this link. It's from Cisco, but the same applies to the Procurve devices. That link explains the differences between the default gateway options, and what routing protocols are affected by each.

The one thing I didn't touch on here is setting your actual routing to be able to reach VLAN 2. For that you'll have to decide what is best because it depends on your network and routing devices and protocols in use. In my example, I need to setup a route in VLAN 1 that would send traffic for to (the switch's IP on VLAN 1). If you have OSPF configured on your network and your switch participates, then you likely have nothing to do here. For my network, the switch doesn't support OSPF and the router is managed by my ISP and I have no access. In order to get traffic to VLAN 2, I added a static route to my firewall for it. That way it still gets advertised over OSPF and VLAN 2 can be reached.

When I initially decided to do this, I used a few articles to come up with the final configuration. In case they may be helpful to you:

Happy VLANing!