# Multicast Activity Overview

> An overview of the multicast activity on your network, and how subscription-based multicast works.

Source: https://docs.capaone.com/performanceguard/i-want-to-know/i-want-to-know-who-generates-ip-traffic/multicast-activity-overview/  
Product: PerformanceGuard — a separate CapaSystems product; do not apply this page to any other.

Multicast is when someone sends a single set of data packets across a network to multiple selected users at the same time. Multicast is subscription-based: Computers that want to receive multicast traffic use ICMP messages to let routers know which multicast addresses they want to subscribe to. The routers are then able to calculate which multicast messages they need to send to receivers on their different interfaces. A packet is considered a multicast packet if the destination IP address is in the range 224.0.0.0 to 239.255.255.255.

The Multicast Activity overview (**ANALYZE > Overview > IP Traffic > Multicast Activity**) lets you view multicast activity in a list format.

1. If you want to limit your results to a particular type of multicast traffic, select required multicast group. Otherwise select **All Multicast**.

:::note[Important]
<details>
<summary>What's a multicast group?</summary>

Multicast groups help you filter your data if you are only interested in a particular type of multicast traffic. PerformanceGuard comes with preconfigured groups for common types of multicast traffic, LLMNR and SSDP, and PerformanceGuard administrators can set up additional groups. See also [Manage Multicast Groups](/performanceguard/administration/more-setup/manage-multicast-groups/).

</details>
:::
2. Select required direction:

   - **Sent**: Outgoing multicast traffic measured on servers that send multicast traffic.  
       
     In the example illustration (click thumbnail to view image in full size) sent multicast traffic is measured on the computer with the green dot:

     ![](/attachments/performanceguard/dc7133f5-232c-42bb-8cdb-3e24a7ba3950.png)
   - **Received**: Incoming multicast traffic measured computers that receive such data.  
       
     In the example illustration (click thumbnail to view image in full size) received multicast traffic is measured on the computers with the green dots:

     ![](/attachments/performanceguard/3ff74a20-5ccd-4fb9-b773-fa21024fb568.png)
3. If required, you can limit your overview to a particular group of computers with the **Agent** menu:

   - If you selected **Sent** in the previous step, use the menu to limit your overview to multicast traffic sent from a particular location/network
   - If you selected **Received** in the previous step, use the menu to limit your overview to multicast traffic received at a particular location/network   
       
     If you don't want to limit your overview this way, select **All agents**.
4. Select the required **Interval** (that is the period of time that you want to cover). If the predefined intervals don't suit you, select **Custom** to [Custom Time Periods on Graphs](/performanceguard/analyze/custom-time-periods-on-graphs/).
5. If required, you can enter all or part of a server IP address to limit the search to multicast servers with that IP address.

:::note[Important]
**Examples:** To limit your search to a server with the IP address 192.168.40.72, specify that IP address. To limit your search to servers with an IP address that begins with 192.168.40, specify those IP address segments in the first three fields, and leave the last field blank.
:::
6. Click the **Update** button.

:::caution
It may take some time to generate the list, especially if you have selected all multicast groups and all computers.
:::

:::tip
You can also view multicast activity in a graph format by selecting **ANALYZE > Graphs > Time View > Multicast Traffic**. See [Multicast Traffic](/performanceguard/i-want-to-know/i-want-to-know-who-generates-ip-traffic/multicast-traffic/).
:::