Rickard Nobel

Troubleshoot ESXi networking with tcpdump-uw

Rickard Nobel — Mon, 06 May 2013 08:10:22 +0000

Tcpdump-uw is a command line packet sniffer available in ESXi. Learn the most useful parameters to troubleshoot ESXi networking. A very valuable help in all network troubleshooting is the ability to actually look at the packets being sent and received. … Continue reading →

Troubleshoot iSCSI TCP connectivity from ESXi with netcat

Rickard Nobel — Mon, 22 Apr 2013 09:00:41 +0000

The ESXi port scanner: how to use the nc command to check if TCP ports on the iSCSI target are reachable. Many VMware administrators might not be aware of ESXi having a simple, but functional, port scanner utility built in. … Continue reading →

The VLAN 802.1Q tag – part 1

Rickard Nobel — Mon, 15 Apr 2013 08:15:35 +0000

How the 802.1Q VLAN tag works: the first part in a series of three posts on the VLAN tagging. In this article we will look at some details on how the 802.1Q tag is constructed and how it affects Ethernet … Continue reading →

VMKping ESXi 5.1 – select outgoing network adapter

Rickard Nobel — Mon, 08 Apr 2013 08:01:12 +0000

VMKping ESXi 5.1 – select outgoing network adapter to verify multipathing connectivity When troubleshooting vSphere ESXi networking we have a new very useful option available in vmkping in ESXi 5.1 which adds the ability to select the outgoing adapter being … Continue reading →

VMFS exposed to Windows – what will happen

Rickard Nobel — Thu, 24 Jan 2013 09:00:38 +0000

The SAN Policy in Windows 2008 R2 and VMware VMFS. How a Windows Server will react when exposed to a LUN from a SAN array is controlled by the “SAN Policy“. This is very important in an environment with Fibre … Continue reading →

Verify VAAI from GUI and command line

Rickard Nobel — Mon, 21 Jan 2013 09:00:54 +0000

How to verify if VMware VAAI is supported on the datastores is not totally straightforward. We shall see how to do this from both the GUI in vSphere client and from the command line through SSH. The VAAI (vSphere API … Continue reading →

ESXi and Flow Control

Rickard Nobel — Mon, 10 Sep 2012 09:00:06 +0000

How to enable and verify Ethernet Flow Control for VMware ESXi with iSCSI / NFS. Flow Control could help physical switches to prevent frame drops under very high network traffic congestion. Flow Control is typically used in IP storage networks. … Continue reading →

ESXi 5.1 Network Health Check with Jumbo Frames

Rickard Nobel — Wed, 05 Sep 2012 06:55:22 +0000

The new Network Health Check feature in ESXi 5.1 tries to identify several different potential network configuration issues. In this blog post we shall study the MTU size test. For information about the VLAN checks please see this post. The … Continue reading →

ESXi 5.1 and BPDU Guard

Rickard Nobel — Thu, 30 Aug 2012 11:29:21 +0000

How to enable the new security feature of BPDU blocking in vSphere ESXi 5.1 networking and why this is important. Spanning Tree is a technology which basically makes sure that the Layer Two network does not contain loops. This is … Continue reading →

ESXi 5.1 Network Health Check VLANs

Rickard Nobel — Wed, 29 Aug 2012 08:52:16 +0000

How to use the new Network Health Check in VMware ESXi 5.1 to verify VLAN configuration on physical switches. A quite common problem is that the configuration for the VLANs that are configured on the Port Groups on virtual switches … Continue reading →