Discovering broadcast and error storms
One of the most commonly seen and troublesome problems in communication networks is broadcast/multicast and error storms. These problems can happen because of layer 2 loops, layer 2-based attacks, a problematic network adapter, or an application or service that sends packets to the network. In this chapter, we will provide some basic recipes to find, isolate, and solve these types of problems.
Note
A broadcast/multicast storm is when you get thousands and even tens of thousands of such packets per second. In most cases, it will exhaust the bandwidth and lock out the network completely.
Getting ready
When these problems occur, the network you usually call on to solve problems will be very slow or it has stopped working.?
Some important facts to remember:
- Broadcasts are not forwarded by routers.
- Broadcasts are not forwarded between VLANs (this is why VLANs are called broadcast domains), so every VLAN is a broadcast domain by itself.
- Error packets are not forwarded...
