Unlike hubs, switches usually prevent promiscuous sniffing. In a switched network environment, a sniffer is limited to capturing broadcast and multicast packets and those traffic sent or received by the same PC as the sniffer running on.
However, most modern switches support SPAN, or called "port mirroring", which is an advanced feature that enables switches to forward all packets to one or more switch ports and allows sniffers capture network traffic of the whole LAN. If you switch doesn't support such monitoring feature, please refer to how to capture others.
Here is a 3-step instruction on how to configure SPAN for Cisco Catalyst 1900 Series Switch.
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