Multicasting windows

In my testing I tried to select to only allow the image to be transferred via multicast but this didn't seem to work. When I disabled multicast the image would still deploy, even with this option set. On each package select properties and then select the 'distribution settings' tab. As shown on both the image and the package, multicast is something that takes place in Windows PE only.

So, setting these options per package will not result in the package being delivered via multicast through normal software distribution. Finally, enable the task sequence advertisement to deliver the image via multicast. On the properties of the advertisement select the 'distribution points' tab as shown. This requirement isn't documented and I spent hours trying to understand why my multicast sessions weren't starting up before realizing this setting was required.

Thats it - we are now ready to go for delivering images via multicast. Let's walk through a couple of scenarios using autocast and scheduled multicast.

In our scenarios we will use PXE booted systems but multicast also works fine when booting from media - the experience is just slightly different when in Windows PE.

Autocast - single machine To test multicast generally you will use a single machine. So, what is your indication that multicast is actually working? When the image begins to deploy you will see that a multicast session is requested, the image is downloaded locally via multicast and then reassembled as shown in the following three screenshots. Autocast - two machines As mentioned, in autocast the first requesting machine will start the multicast as shown above.

Any subsequent machines that boot up during the existing multicast session will join in progress and then loop back to the start and request the initial bits again. The screenshots below show two sysems - the one on the left was started ahead of the one on the right but both are downloading the same image.

The one on the right started mid-stream. After downloading the image the one on the left proceeds to extract while the one on the right finishes up getting the image. Scheduled multicast works similarly except here the multicast session will not start until either time has expired or the minimum number of machines have joined the multicast session. The screenshot below shows a system waiting for either more systems to join or the timeout to expire.

So, while this is all going on - what is happening in the background to make this all work? In the log snip below we see the imaging system flag the multicast enabled distribution point that it wants to use for the multicast session, construct details for the multicast session request and then send the request to the multicast point.

Continuing in the log we see the request information submitted to the multicast point followed by a reply with information the imaging system needs to join the multicast session. Once we get the proper information back from the multicast point we then request and establish the multicast session. When initially setting up the multicast session we say reference to sending information to the multicast point.

If we look in the mcsisapi log we see the request received, processed and the resulting reply sent back to the imaging agent as shown. There is certainly more 'behind the scenes' detail that takes place but this give a good picture, end to end, of how to configure, use and understand the process of using multicasting in R2. You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.

Products 72 Special Topics 41 Video Hub Skip to main content. This browser is no longer supported. Download Microsoft Edge More info. Contents Exit focus mode. Please rate your experience Yes No. Any additional feedback? In this article. Enumerates the multicast socket options available for use in Windows Sockets programming, using a change-based programming approach. Defines two multicast application categories. Multicast Socket Option Behavior.

You can clearly see the markings I have put at the bottom which show you that the destination IP for this packet is IP Address This corresponds to a multicast IP and therefore is a multicast packet.

The MAC header also shows a destination MAC address of E which we analysed in the previous section to show you how this is identified as a multicast packet at Layer 2 Datalink Layer. There is a rule for the mapping, and this is it:.

The rest of the high-order bits are defined by the IEEE yellow colour in the example. The above rule basically determines the Hardware MAC address. Let's have a look at a real example to understand this.

We are going to use Multicast IP Address The picture below shows us the analysis of the IP address in binary so we can clearly see all the bits:.

We have an IP Address of So the yellow and pink line make the one MAC Address as shown in binary mode, then we convert it from binary to hex and that's about it! You should keep in mind that multicast routers should not forward any multicast datagram with destination addresses in the following The next page multicasting list gives a bit more information on this.

This concludes our discussion on how Multicast works. For more information on network protocols, analysis and functionality, please visit our Network Protocols or Network Fundamentals section. Back to Network Fundamentals Section. Deal with bandwidth spikes Free Download.

Web Vulnerability Scanner Free Download. Network Security Scan Download Now. Breaking things down And this is how they do it: Ethernet uses the low-order bit of the high-order octet to distinguish conventional unicast addresses from multicast addresses. A unicast would have this bit set to ZERO 0 , whereas a multicast would be set to ONE 1 To understand this, we need to analyse the destination MAC address of a unicast and multicast packet, so you can see what we are talking about: When a normal unicast packet is put on the network by a computer, it contains the Source and Destination MAC address, found in the 2nd Layer of the OSI model.

Notice the destination MAC address it's a multicast : Analysis of a multicast destination MAC address: So now you should be able to understand how computers can differentiate between a normal or unicast packet and a multicast packet.