In a previous blog, we covered the basics of multicast routing. Multicast is preferred over unicast and broadcast by content and service provider networks for IPTV, video content distribution, stock market live feeds, and in data centers to synchronize data between servers. Large enterprises also use multicast for video surveillance and teleconferencing. Because multicast is used for these critical and high-volume applications, any downtime can lead to major loss of revenue and customer churn.
In this blog post, we will look at the challenges of running multicast applications and how you can monitor and manage multicast networks.
Though multicast requires considerably less resources and reduces delay when compared to unicast, it does not provide the same level of visibility. With unicast, a single source sends to a single destination and the IP address of each participating device is known. But with multicast, a single source sends to a group of devices – a host group – that can be dynamic. This makes managing and monitoring network performance more complex and many network operators are challenged to know what multicast addresses are used in their network and what they are used for. For example, a financial services organization we talked to estimated there are sixteen thousand multicast groups in their network. While they would like to reduce that number, they can’t because they do not know what each group is used for.
There are other challenges associated with running a multicast network. Here are four common issues:
Traditional network and traffic monitoring tools are insufficient for monitoring multicast routing. Information from SNMP MIBs provides no visibility into multicast logical constructs and these tools often lack information about the underlying IGP and BGP control plane.
Enterprises, content and network service providers who operate multicast networks require specialized tools that collect multicast routing topology (groups, trees, sources and receivers), establish baselines, detect changes and correlate them with underlying IGP and BGP routing changes. With this information, when a link goes down, they can be alerted that all multicast trees using the link will have to re-converge.
Monitoring tools must also track multicast-specific issues, such as RP mismatches, interfaces without PIM enabled, PIM interfaces with no router connection, groups with no receivers, etc., and issue alerts so that preventive actions can be taken quickly.
We hope to have highlighted some of the complexities of managing and monitoring multicast networks. Have you faced any of these challenges in your multicast network?
If you have or would like to learn more about monitoring and managing multicast better, download our whitepaper that covers all this and more in detail: