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flapping connectivity (VIRUS?)

Hi, Recently i noticed our internet connection suddenly became very slow. While troubleshooting i noticed connecting one system directly to my IDU i get satble replies from my external DNS, but when i connect to the LAN i get something like

Reply from 199.?.?.?: bytes=32 time=827ms TTL=233

Reply from 199.?.?.?: bytes=32 time=906ms TTL=233

Reply from 199.?.?.?: bytes=32 time=1048ms TTL=233

Reply from 199.?.?.?: bytes=32 time=1143ms TTL=233

Reply from 199.?.?.?: bytes=32 time=995ms TTL=233

Request timed out.

Reply from 199.?.?.?: bytes=32 time=1208ms TTL=233

Request timed out.

Request timed out.

Reply from 199.?.?.?: bytes=32 time=1363ms TTL=233

Request timed out.

Reply from 199.?.?.?: bytes=32 time=1483ms TTL=233

Request timed out.

Reply from 199.?.?.?: bytes=32 time=1392ms TTL=233

Request timed out.

Reply from 199.?.?.?: bytes=32 time=1207ms TTL=233

Request timed out.

Reply from 199.?.?.?: bytes=32 time=1117ms TTL=233

What could be the explanation for this. I have tried to isolate switches and systems, i realised it is either one of the switches or a device connected to it.I pull out from port 5 for e.g and it all goes smoothly for a while and seems like a virus looking for ports to hijack, put port 5 back it gets stable for a while and then i have to look for the "affected" port(may be port 12) and pull out again My question is, why does this happen why does it affest the entire LAN. What can i do? Can switches and routers be infected with virus? if so, how are they removed?

Thanks

Toyin

1 REPLY
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Re: flapping connectivity (VIRUS?)

one way is to use a sniffer to examine what exactly is happening in the lan.

there are plenty of free sniffer, such as ethereal.

further, port mirror may needs to be configured on the switch.

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