CDO Mode in NSX Controller

CDO  ( Controller disconnect operation) Mode in NSX Controller.

CDO mode ensures that the data plane connectivity in the multisite environment. When primary site loses connectivity. Here you can enable CDO mode on secondary site to avoid any temporary connectivity issue related to data plane. 

When the primary site is down or not reachable, the CDO logical switch is used only for control plane. Purpose and therefore its a not visible under logical switches tab.

About VTEP Reports

VTEP Reports

NSX Controller VXLAN directory services. There are basically 3 types of tables under VTEP

1) MAC Table

2) ARP Table

3) VTEP Table

MAC Table: 

The MAC table includes the VNI, the MAC address and VTEP ID that reported it.If a unknown unicast frame is reviewed by a VTEP. The VTEP sends a MAC table request to NSX Controller for a destination MAC address.

If NSX controller has the MAC address in the MAC table, it replies to the VTEP with information on where to forward the frame.

If NSX controller does not have MAC address in the MAC table then the VTEP floods the frame to other VTEP's.

ARP Table:

The ARP table used to suppress the broadcast traffic.

IP report generate the ARP Table. The VTEP's send a copy to each MAC address and IP mapping that they have. This report is called the IP reports.

NSX controller creates a ARP table with the information in the IP request.

The ARP table includes the MAC to IP addrEss mapping and VTEP IP that reported it.

The VTEP intercepts all APR reques…

NSX VXLAN Logical Switch Replication mode

NSX VXLAN Logical Switch Replication Mode.

NSX controller is the central control point for all logical switches within a network and maintain information of all virtual machine, host, logical switch and VXLAN.

The controller support two new logical switch control plane mode.

1) Unicast
2) Hybrid

The replication mode tells NSX to manage BUM traffic which sent from virtual machine.

Multicast mode

Control plane operation is based on multicast flooding and learning.BUM traffic replication is based on L2 and L3 multicast.It require 1GMP and multicast routing.
Unicast Mode
Control Plane operation is based on NSX controller cluster.BUM traffic replication is based on unicast . (One destination at a time)Host depend on UTEP (unicast TAP) for replication for traffic on remote signal.

Hybrid Mode
Bum traffic replication based on unicast and L2 multicast. Local replication is offloaded to physical network. Remote replication is based on unicast.

Overview on VXLAN


(Virtual Extensible Local Area Network)

Logical Switch reproduce switching functionality (Unicast, multicast or broadcast) in virtual environment which completely decouple from underlying hardware.

Logical Switches are similar to VXLAN in that they provides network connections to which you can attach virtual machine. The VM's can communicate with each other over VXLAN if they are connected to some logical switches.


The DLR support logical switches which are backed by VXLAN.

First-hop routing is handling on the host, the traffic is switched to appropriate logical switch. If the destination is at another host. the ethernet frame is placed in the VXLAN frame & forward.
Only one VXLAN LIF can connect to logical switch. The next-hop can be an NSX Edge service gateway.
VXLAN LIF can span all distributed switch in the transport zone.

VMware vForum 2019 - Online

The new year is well under way, and with 2019 in full swing, tech conference chatter will start to heat up. While VMworld is just over six months away, there are still opportunities to get your dose of VMware updates well before then. One of those opportunities is VMware’s vForum Online, which will take place on April 24th, 2019

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"Unknown" status showing in host compliance status

There were several practices where we use host profile into our environment to get the compliance among all other ESXi host into the cluster.

There are mostly 3 types of status identified to the hostprofile which is attached to the ESXi host.

1) Compliant
2) Not-compliant
3) Unknown

As you know when all the features and settings of host profile and ESXi meets perfectly then only status shows as Compliant status.
Not-compliance status shows when the hostpofile unable to meet the complete requirement on the host and some feature are missing.
Unknown status is the one which suspect even when you have ESXi host into the Compliance status or sometime could be in Not-compliant status.

There are several indentified cause for that.

Most of the time we found that all good from ESXi UI and hostprofile where all the parameters are meet successfully and even then host profile status shows as "UNKNOWN" status.

In my case i found one glitch where the dvs configuration was not sync comple…

RAM Disk Full Due To Inodes In ESXi Host

Last week I got into issue where one of my ESXi host was prompting error while creating virtual machine.

I verified the task and events of ESXi host and found below error generating while creating Virtual machine "A general system error occured: Failed to open "/var/log/vmware/journel/ for write: There is no space". While further digging, I identified the ESXi host from where its generating this error from Task and Event section in vCenter.
Tried to take SSH of the question ESXi host but its was inaccessible via putty. However, ESXi host was up and running fine. Last option left to access the ESXi host from its management console which is ILO as its ESXi installed on HP server.

Also you can try accessing the SSH via other ESXi host or Linux machine using below command ssh -T servername. However, this will not give your prompt but you can type the command to get the output, but that was not giving any luck at that time so we use ILO for further troubleshooting.
Took th…

RAM Disk full on ESXi host

Sometime we used to get issue where were are not able to perform vMotion or logging was unable to write under /var/log.. While trying to do some normal things – like vMotion. I noticed an error which states just “A general system error occurred.”  On further investigation, I found that the underlying message was an out of disk space message while trying to proceed with a Storage vMotion. Observations during issueWhile vMotion– “A general system error occurred:” While performing Storage vMotion – “/var/log/vmware/journal/xxxx error writing file. There is no space left on the device.” Steps during troubleshootingGo to Configuration tab on host in vCenter client, go to Security Profile, click Properties link on the Services section.Scroll down to SSH and highlight – click options – click start to start SSH service.Use putty or reflections to ssh to the host.If you get a connection rejected – root filesystem ramdisk is probably full.Go to console (either through KVM or OA for blades)F2 to …

Monitoring VCSA & PSC disk partitions from vRop's

In our day to day life we encounter many disk alert issue on different operating system when they move above predefined threshold size.

Here, in this article we go through how we can set alert and notification of disk partitions of VCSA and PSC.

Here we'll take example of VCSA 6.5 ( Appliance) which has following partitions in Guest OS as mentioned in Fig.1


Here we'll set alert of partitons like /storage/seat , /storage/db, /storage/autodeploy, /storage/log etc..

To start we defined we set of steps.

Overall process of creating alert definition are below:
Create a Symptom > Add these symptoms to Alert Definition > Then create a Notification for the Alert Definitions

What is Symptom:
The symptom sets comprise an expression that is evaluated to determine if an alert should be triggered. To add one or more symptoms from the symptom list to an existing symptom set, drag the symptom from the list to the symptom set. To create a new symptom set for the alert definition, …

Oracle Linux VM unable to boot after P2V conversion.

Recently, I was having issue where I had decided to migrate one of my Oracle Linux machine which was running in HP Blade server to visualize and migrated through VMware converter.
Migration went successful and VM migrated successfully without any error but while powering on the Oracle Linux VM its failed with below error.

To resolve this issue I tried to boot the VM with Linix iso and run into rescue mode.
Please find below steps which I followed to boot the VM successfully.
1)Mount the linux iso to the VM and boot it from CD 2)At the first prompt, type linux rescue and press Enter. 3)Change root to the mounted installation. Type chroot /mnt/sysimage and press Enter 4)Type ls /boot 5)There you will see lots of initrd-xxxxx.EL.img files with different name. 6)To verify the correct initrd-file used to /boot. Type cat /etc/grub.conf, and press Enter. 7)From the location /etc/grub.conf I found there are two initrd files was there with the same name. From the initial error before traceback its s…