NETWORKING

Written by Sam McGeown on 20/10/2014
I am aware that that’s not a catchy blog post title. In fact, it doesn’t even really describe the problem or solution very well - for that I need to go into a little bit more depth! Suppose I have configured a Reservation with two Networks ticked (“192.168.1.0-VLAN1” and “192.168.10.0-VLAN10”). As you can see in the screenshot below, each of the networks has a Network Profile created and assigned with a network pool to provide IP addressing for the VMs.
Written by Sam McGeown on 4/4/2014
Published under Networking
I recently got my hands on a copy* of Chris Wahl and Steve Pantol’s Networking for VMware Administrators and was very keen to read it – especially given the reputation of the authors. I came to the book as someone who is at CCNA level (although now expired) and someone who regularly designs complex VMware networks using standard and distributed switches. I would class myself as having a fairly decent understanding of networking, though not a networking specialist.
Written by Sam McGeown on 16/10/2013
Published under VMware
Today was always going to be a bit of a funny day as I scheduled the VCAP5-DCD exam for 10am this morning. I am happy to say that I passed! I’m a bit light on VMworld to report today, so forgive my DCD experience to pad it out! Preparation I have to confess my prep for this exam was light – I literally only watched the TrainSignal course by Scott Lowe (@scott_lowe) and just about finished that last night in the hotel!
Written by Sam McGeown on 24/3/2010
Published under Microsoft and Networking
So, you’ve installed a new server with Server 2008 R2 Core – what next? Logging on, you’re presented with a shiny command prompt, you can run notepad or regedit…but aside from that, where do you go from there? In the next few series of posts I’ll hopefully point out the basics, and some not so basics! Using the Server Configuration Tool The server configuration tool (sconfig.cmd) is provided in R2 for some of the basic setup tasks, so you can run that by issuing the “sconfig” command.
Written by Sam McGeown on 26/2/2010
Published under
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.
Written by Sam McGeown on 30/9/2009
Published under Networking and VMware
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.
Written by Sam McGeown on 21/9/2009
Published under Microsoft and Networking
I recently resolved an ongoing DNS issue where the Active Directory Integrated DNS was loaded in both the Domain and the DomainDNSZones partition of AD - this is a separate issue and should be resolved differently. My problem when I tried to verify that the fixed DNS setup had propogated around my domain controllers, DC01 and DC02. DC01 kept failing “DCDIAG /TEST:DNS” with errors regarding the root hint servers. Googling about it was clear that a lot of people were suffering the same issue, but no article I read had correctly identified the solution.
Written by Sam McGeown on 10/9/2009
Published under
I recently had an issue where a hosting environment was registering a lot of Netlogon Event 1030⁄1058 issues, being unable to find the Group Policy objects or download them. In this example, the server DC is the domain controller for DOMAIN.LCL. _Event Type: Error Event Source: Userenv Event Category: None Event ID: 1030 Date:  10/09/2009 Time:  06:24:29 User:  NT AUTHORITY\SYSTEM Computer: DC Description: Windows cannot query for the list of Group Policy objects. Check the event log for possible messages previously logged by the policy engine that describes the reason for this.
Written by Sam McGeown on 15/1/2009
Published under Microsoft
If you’re getting a error on your LAN connection it’s possible that your network connection is attempting 802.11 authentication on your wired network. Unfortunately, it seems that Vista/Server 2008 both attempt it before reverting. As far as I can see, it’s not causing any issues, other than irritating me with a “failed” and a red question mark. Fortunately, it’s pretty easy to fix! The authentication is handled by the Wired AutoConfig service, so it’s just a case of disabling it.
Written by Sam McGeown on 24/11/2008
Published under Networking
I was configuring our new Cisco ASA 5510 firewall today, as part of a major infrastructure upgrade. I’m pretty comfortable with the Cisco IOS, but I still prefer the GUI for the basic set up, using command line to tweak the finer or more complex configurations. However, straight out of the box, I had a very hard time getting the ASDM to load. Being familiar with the PDM from the PIX range of firewalls, I should have guessed the problem straight away.