From the course: CCNP Switching (300-115) Cert Prep: 1 Layer 2 Technologies

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SPAN and RSPAN

SPAN and RSPAN

- [Instructor] Often, when devices are having trouble communicating, I hear the too-common phrase, it must be the network. I actually own a t-shirt that says, it's definitely not the network. But network engineers are guilty until proven innocent. Sometimes, the best course of action to diagnose an issue is to perform a packet capture of the information as it traverses a switch. If hosts in the same VLAN are experiencing issues, an administrator can't simply connect to another port in that VLAN. The only thing captured from these hosts would be broadcast, or possibly multicast, traffic. If a packet capture is to happen from another available interface on a switch, it must be done from a specially-configured port. This process uses Cisco's switched port analyzer, or SPAN feature. VLANs, or interfaces, are configured so that source or destination packets are marked, then copied over to a specified mirror port. There are two types of SPAN ports, local and remote. Local SPANs have source…

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