networking Archives

iSCSI Bug – Traffic Routed Out Wrong Interface – Update

September 19, 2012 By Josh Townsend 3 Comments

One of my most popular posts to date has been 'vSphere 5 Networking Bug Affects Software iSCSI' with some 20,000 page views and a bunch of comments. The problem is a bug that causes vmkernel traffic (including iSCSI) to be sent out the unused/inactive/null NIC on a vSwitch with a manual failover order and Active and Unused vmnics. It still appears that the issue I covered is affecting customers - we just had a new Clearpath customer call for help with this very issue. VMware's KB on the issue … [Read more...]

Filed Under: VMware Tagged With: bug, esxi 5, failover, iscsi, network, networking, NIC, troubleshooting, vDS, vmknic, vmnic, VMware, vsphere 5, vswitch

vSphere 5 Networking Bug #2 Affects Management Network Connectivity

February 10, 2012 By Josh Townsend 30 Comments

On Wednesday, I wrote about a VMware vSphere 5 networking bug that caused issues with iSCSI networking. That bug, described in VMware KB 2008144 caused vmk traffic to be sent over the unused vmnic uplink in a team where there is an unused uplink and an explicit failover policy present. See the diagram below to better understand what was going on there…. The second bug vSphere 5 networking bug I experienced was similar to the first: traffic was sent out of an unexpected interface after upgrading to ESXi 5. This particular bug surfaced while troubleshooting my iSCSI bug (because why … [Read more...]

Filed Under: Issues & Troubleshooting, VMware Tagged With: bug, connectivity, esxi 5, networking, troubleshooting, vDS, vsphere 5, vswitch

vSphere 5 Networking Bug Affects Software iSCSI

February 8, 2012 By Josh Townsend 88 Comments

Update 1: This issue was fixed as of 3/15/2012 in ESXi 5.0 Update 1 per the original knowledge base article: VMware KB 2008144. To download ESXi 5.0/vCenter Server 5.0 Update 1, see the VMware Download Center. Update 2 (Nov 7 2012): While VMware says the issue was fixed in vSphere 5.0 Update 1, I have not found this to be the case. I've had several environments where the bug was still present, and in some cases this nasty bug still appeared when implementing the Failback = NO setting on the vSwitch. Additionally, setting Failback = No may cause some other problems - see my update here … [Read more...]

Filed Under: Issues & Troubleshooting, VMware, VMware How To Tagged With: esxi 5, failback, iscsi, multipath, network, networking, NIC, performance, Storage, troubleshooting, vDS, vmknic, vmnic, vsphere 5, vswitch

VMware Networking Demysified

March 20, 2009 By Josh Townsend 1 Comment

VMware vExpert and fellow Northern Virginian, Ken Cline, has posted an excellent article on his Ken's Virtual Reality blog that aims to demystify VMware networking. The article, the first in a new series by Ken, provides an overview of networking in an ESX/ESXi environment and breaks down the intricacies of the vSwitch and VLANs. The article comes complete with some nifty diagrams to help make sense of the topic. The timing of this article is great for me as it helps to frame my thoughts as I delve into the design of my latest VMware project on an IBM BladeCenter with IP SAN … [Read more...]