Storm control is a feature for monitoring traffic levels and dropping broadcast, multicast, and unknown unicast packets, which is commonly known as BUM Traffic, and when a specified traffic level, referred to as the storm control level or storm control bandwidth is exceeded, limiting the traffic to protect the Local Area Network environment. In this blog post, we will try to understand the basics of it.
We need to understand some terminologies if we want to understand Storm control and its usage on Network Switch. In the above configuration, we will show not only for Broadcast but also for Multicast and Unknown Unicast threshold levels on the Cisco switches.
interface GigabitEthernet0/0 storm-control broadcast level bps 100k 90k storm-control multicast level pps 50 30 storm-control unicast level 1.00 0.50On the above configuration, the below parameters are used. Let's briefly define each one of them.
Meaning at 100kbit/s traffic will be blocked when the traffic level falls under 90kbit/s again. traffic will be forwarded. This feature is and should be used in real-life in the campus networks/local area networks, where you have a Layer 2 domain. When the Layer 2 domain gets larger, the importance of the Storm Control feature increases as well. You can find more information on Layer 2 network design, in our Layer2 Network Design Course.
Orhan Ergun, CCIE/CCDE Trainer, Author of Many Networking Books, Network Design Advisor, and Cisco Champion 2019/2020/2021
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