As some of you read previously, I had been experiencing disk latency issues on our SAN and tried many initial methods to troubleshoot and understand the root cause. Due to other more pressing issues this was placed aside until we started to experience VMs being occasionaly restarted by vSphere HA as the lock had been lost on a given VMDK file. (NOT GOOD!!) The Environment:- 3x vSphere 5.1 Hosts
Firewalls being used – Sonicwall 3500 & Cisco 506e Several months ago we relocated and it was then necessary to setup a Site to Site VPN tunnel with another network. (In this instance the other network was not directly managed by us) Upon the creation of the tunnel and after successful traffic tests all looked well. However after several hours or less in some cases traffic stopped flowing yet both firewalls reported the tunnel as “up”.
It’s a fairly common requirement – setting up a guest WiFi network that is secure from the rest of your LAN. You need a secure WLAN access for the domain laptops which has full access to the Server and Client VLANs, but you also need a guest WLAN for visitors to the office which only allows internet access. Since the budget is limited, this must all be accomplished via a single Access Point – for this article, the access point is a Cisco WAP4410N.
We run to monitoring systems where I work, the first is HP SIM and the second is Microsoft System Center Operations Manager. Currently, they and their databases all reside on a single rather battered server, “MONITOR1”. I’ve installed a new SQL Server 2008 server “SQL1” on Windows Server 2008 to take some of the load, and take advantage of the 64-bit OS and SQL installation. Both servers are part of the domain “DOMAIN”
No matter how good your network diagrams are, sometimes you need to verify the port your server/desktop is in. Cisco Discovery Protocol is a great tool for network admins when you need to quickly map routers and switches, and if you’ve got an ESX server connected you’ll see that it picks up CDP info too – but the vast majority of my managed systems are Windows. Here’s how to use TCPDUMP by Micro Olap to extend that functionality to your Windows boxes.
After some pretty heavy investment in terms of time and money, I’ve passed my ICND2 exam and am now qualified as a Cisco Certified Network Associate (anyone else find it odd that you’re not even considered a professional by Cisco at this level?!) I do consider the Cisco qualifications as significantly more valuable than the others that I hold, simply because of the difficulty of the exams. I do find them “honest” in that they’re not trick questions, and you don’t need a technique to pass – just in depth knowledge.
As is normally the case when I’m studying, I haven’t had time to post much on here lately. I’ve been studying to pass the ICND1 exam (snappily titled “Interconnecting Cisco Network Devices Part 1”) I’m really pleased to say that neglecting this site paid off, or rather the study did – I passed with a score of 930! It was a LOT harder than I had expected, I thought I’d walk out after 20m!
Here’s the setup. We have a core switch of 2 Cisco 3750s, connected together for fault tolerance as a single logical switch; we also have several ESX 3.5 hosts with 4 Gigabit Ethernet NICs installed each. The Virtual Machines will all be on VLAN 8 (reserved for internal servers) and the VMKernel will be on VLAN 107 (reserved for VMKernel traffic like VMotion). I want to create a load balanced, fault tolerant aggregate of these four NICs over the Core Switch.
Like thousands of other IT pros out there, I’m testing Windows 7 out on my laptop - since I don’t want to mess around with my main PC, it’s running on some older kit. The problem with that is that there aren’t many Vista drivers around for the hardware - why would there be, it’s not even supposed to be able to run Vista?! It does, however, run Windows 7 very admirably (just one of the many improvements).
I have to support about 20 laptops with 3G connections in them, they’re all Dell and range from D800s with PCMCIA 3G data cards, D830s with internal Dell Wireless 5520 Modems and some newer E4200s with internal Dell Wireless 5530 Modems. Both the D830s and the E4200s are shipped with Dell software to manage the connections. The D800s use Vodafone Mobile Connect, and have never, ever, caused me a problem.