network crash when I connect a Windows PC with a static IP

[dexter87456123]

Hi,

when I connect a PC to my corporate network with a static IP 192.168.x.x without correct DNS (subnet not present in the network) a sort of broadcast storm occurs that creates a network block and related packet loss.

The switches seem to no longer respond correctly and the only way to restart everything is to reboot the switches.

has this ever happened to anyone?
thanks

[Flavio Miranda]

@dexter87456123 

  You need to check your switch. You probably have a loop on the network. How is your topology? Which network devices do you have?

[Cristian Matei]

Hi,

    We've got to delineate here; seeing Windows hosts that generate insane amounts of broadcast packets (sometimes ARP), yes, well-known bugs and issues; however, a single host is not capable of melting down a network; by switches no longer respond I understand that you can no longer reach it via IP and connect to it (all that broadcast traffic is going to the switch CPU and killing it as well, if the switch has a layer 3 interface within that VLAN); us storm-control to filter out and isolate such hosts that have undesired behaviours.

Best,

Cristian.

[dexter87456123]

Hi,

we have already checked and there are no loops at the wiring level.

The problem seems to be a broadcast storm. We thought it was a NetBios problem and we went to disable it on all clients but it did not solve it.

The vlan on which the problem occurs has about 150 hosts
When the pc is connected with that static configuration all the eth networks of the other clients suffer and the switches in the network start to have interruptions (same behavior as a loop)

Surely the solution will be to segment the network but we wanted to understand the problem, I do not think that 150 hosts on a vlan are a lot

what could be the causes?

[Flavio Miranda]

Can you share the switch configuration? show running-config ?

[Cristian Matei]

Hi,

    Broadcast storm might hit the switch CPU mate; just configure storm-control and filter out that traffic at network ingress, or err-disable the port: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9300/software/release/16-11/configuration_guide/sec/b_1611_sec_9300_cg/configuring_port_based_traffic_control.html

Best,

Cristian.

[MHM Cisco World]

First you mention static IP' so do check if there is any other device use same IP.

Second boradcast strom!! How you know that? 

You need to check the port connect to PC do show interface and see boradcast count is it increase rapidly or not.

And if ypu have boradcast strom then issue is in PC and to protect SW use broadcast threshold in port.

MHM