Can heavy UDP traffic create network congestion?

Question

I have three IP addresses using the same gateway. Two of them are configured as a cluster with multicast address setup. If there is a heavy UDP traffic between those two, can that affect the network on the third IP address ?

Answer 1

Could the network be configured so this is not a problem? Yes.

Could the network be configured so this is a problem? Yes, but unlikely.

The simplest configuration (everything plugged in to a simple Ethernet switch) would likely not be overwhelmed by the cluster's UDP traffic because of the congestion control properties of IP.

Answer 2

It depends on the traffic pattern. Bandwith isn't everything..

99% of the switches out there are designed as access switches, who typically have very small buffers on each port, or on a subset of ports. If you are doing very heavy traffic with a high amount of PPS (packets per second) you could potentially fill up the switch buffer, or even worse, exhaust the ASIC (if there is one on your switch) and then trigger software switching in the CPU.

These are all big if's, and it's impossible to give you an exact answer without a very detailed documentation of your environment. Just don't go shopping for an access switch (even a Cisco 2960S counts as access switch) and expect tremendous performance with a million packets per second..