Skip to main content

[How to] Enable Multi-cast in VMware on AWS - NSX environment

I had a customer who were running few application VMs in their on-premises datacenter which uses multicasting as main mechanism in order to form cluster blocks. They are in process of migrating the workloads from On-premises to VMware on AWS SDDCs. The application Architect wanted to ensure that the VMC supports multicasting within AWS VMC so that they migrate the VMS ( Life & Shift) without major downtime/config changes to their applications clusters.

Let's see how things works within VMC world

In VMC setup the Multi casting feature is enabled by default. In SDDC networks, layer 2 multicast traffic is treated as broadcast traffic on the network segment where the traffic originates. It is not routed beyond that segment.  

VMC Limitation: 

Optimisation features such as IGMP snooping are not supported. 
Layer 3 multicast (such as Protocol Independent Multicast) is not supported in VMware Cloud on AWS.  


In the above example case, the customer has L2 multicast, let's check if the things work by using the omping command.

Example: Run omping command from source VM to the destination VM. ( Make sure the VMs are in the same SDDC Cluster within the SDDC and uses the segments within the VMC range from NSX) 1. omping -m 239.192.197.125 -p 9106 172.11.78.18


Check if the source vm is able to receive the multi cast response from the destination. If you get the error " omping: Given address 172.11.78.18 is not valid multicast address" then the things are not working as expected. 


In my case the customer had the VMware Distributed firewall in place. In that case, we had to allow the multicast address range in the DFW firewall inorder to make things work. 

Below are the rules were created in the DFW. 

Configuration change at NSX DFW: (Is need only if it does not work by default)  

  • Allow the source and destination ports explicitly. Example, if the source VM IP range is 192.17.41.0/24, then enable UDP communication between the networks (multicast): 172.11.78.0/24 224.0.0.0/4.  
  • In DFW, create a new rule for this traffic. Source IP is 172.11.78.0/24 and destination is 224.0.0.0/4. The port is ANY and protocol is UDP.  

  1. Use the OMPING to confirm post the network changes  






Labels:

Popular posts from this blog

AD LDS – Syncronizing AD LDS with Active Directory

First, we will install the AD LDS Instance: 1. Create and AD LDS instance by clicking Start -> Administrative Tools -> Active Directory Lightweight Directory Services Setup Wizard. The Setup Wizard appears. 2. Click Next . The Setup Options dialog box appears. For the sake of this guide, a unique instance will be the primary focus. I will have a separate post regarding AD LDS replication at some point in the near future. 3. Select A unique instance . 4. Click Next and the Instance Name dialog box appears. The instance name will help you identify and differentiate it from other instances that you may have installed on the same end point. The instance name will be listed in the data directory for the instance as well as in the Add or Remove Programs snap-in. 5. Enter a unique instance name, for example IDG. 6. Click Next to display the Ports configuration dialog box. 7. Leave ports at their default values unless you have conflicts with the default values. 8. Click N...
Read more

HOW TO EDIT THE BCD REGISTRY FILE

The BCD registry file controls which operating system installation starts and how long the boot manager waits before starting Windows. Basically, it’s like the Boot.ini file in earlier versions of Windows. If you need to edit it, the easiest way is to use the Startup And Recovery tool from within Vista. Just follow these steps: 1. Click Start. Right-click Computer, and then click Properties. 2. Click Advanced System Settings. 3. On the Advanced tab, under Startup and Recovery, click Settings. 4. Click the Default Operating System list, and edit other startup settings. Then, click OK. Same as Windows XP, right? But you’re probably not here because you couldn’t find that dialog box. You’re probably here because Windows Vista won’t start. In that case, you shouldn’t even worry about editing the BCD. Just run Startup Repair, and let the tool do what it’s supposed to. If you’re an advanced user, like an IT guy, you might want to edit the BCD file yourself. You can do this...
Read more

DNS Scavenging.

                        DNS Scavenging is a great answer to a problem that has been nagging everyone since RFC 2136 came out way back in 1997.  Despite many clever methods of ensuring that clients and DHCP servers that perform dynamic updates clean up after themselves sometimes DNS can get messy.  Remember that old test server that you built two years ago that caught fire before it could be used?  Probably not.  DNS still remembers it though.  There are two big issues with DNS scavenging that seem to come up a lot: "I'm hitting this 'scavenge now' button like a snare drum and nothing is happening.  Why?" or "I woke up this morning, my DNS zones are nearly empty and Active Directory is sitting in a corner rocking back and forth crying.  What happened?" This post should help us figure out when the first issue will happen and completely av...
Read more