Combing/integrating two switches virtually and make them work as one , a redundancy feature called Virtual switching system (VSS).
The main reason for VSS is something that is typically addressed when there are redundant routing platforms on a network. A VSS is network system virtualization technology that pools multiple Cisco switches into one virtual switch, increasing operational efficiency, boosting nonstop communications, and scaling system bandwidth capacity to 1.4 Tbps.
VSS actually removes the need for a next-hop redundancy protocol like HSRP or VRRP. These first-hop redundancy protocols are usually heavily tied to a fast-converging routing protocol like EIGRP, and still require that each device maintain it’s own control plane. Often, two switches are configured, and one responds to ARP requests while the other does not. This is an active/passive relationship. VSS takes this a step further and actually merges the two switches into one virtual “mega-switch”, rather than wasting a perfectly good switch. There’s still a master/slave relationship, but rather than placing one switch in standby while the other is active, this determines which switch maintains control over the other. The function of the supervisor module, as well as the configuration of both switches, becomes the responsibility of the primary switch.
VSS utilizes the port channel between the switches to merge them together into one massive switch. As a result, redundant connections from the Access layer to the Core no longer need to be blocked because since they’re virtually both connected to the same switch, they can be configured in a port-channel, as shown by the diagram to the right. http://www.cisco.com/c/en/us/products/collateral/switches/catalyst-6500-virtual-switching-system-1440/prod_qas0900aecd806ed74b.html
The main reason for VSS is something that is typically addressed when there are redundant routing platforms on a network. A VSS is network system virtualization technology that pools multiple Cisco switches into one virtual switch, increasing operational efficiency, boosting nonstop communications, and scaling system bandwidth capacity to 1.4 Tbps.
VSS actually removes the need for a next-hop redundancy protocol like HSRP or VRRP. These first-hop redundancy protocols are usually heavily tied to a fast-converging routing protocol like EIGRP, and still require that each device maintain it’s own control plane. Often, two switches are configured, and one responds to ARP requests while the other does not. This is an active/passive relationship. VSS takes this a step further and actually merges the two switches into one virtual “mega-switch”, rather than wasting a perfectly good switch. There’s still a master/slave relationship, but rather than placing one switch in standby while the other is active, this determines which switch maintains control over the other. The function of the supervisor module, as well as the configuration of both switches, becomes the responsibility of the primary switch.
VSS utilizes the port channel between the switches to merge them together into one massive switch. As a result, redundant connections from the Access layer to the Core no longer need to be blocked because since they’re virtually both connected to the same switch, they can be configured in a port-channel, as shown by the diagram to the right. http://www.cisco.com/c/en/us/products/collateral/switches/catalyst-6500-virtual-switching-system-1440/prod_qas0900aecd806ed74b.html
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