Virtual Switching System (VSS) allows two Cisco Catalyst 6500 or 4500 switches to be connected together so that they appear to the network as a single switch. Other devices in the network will see the VSS configured switches as a single switch, which allows the engineer the ability to create multi chassis Ether-Channels between the VSS pair and other devices while appearing to other protocols like spanning-tree as a single switch.
By far the best feature of VSS is NSF (Non Stop Forwarding) / SSO (Stateful Switchover) which allows the failure of a single device without any downtime. This is due to the routing table / CEF table etc. being stored in supervisor module of both chassis, allowing one device to take over when the other fails similar to the failover that occurs between supervisor modules in a switch equipped with dual supervisors.
Another great feature of VSS is the ability to have a single point to make changes. Changes made to configuration or IOS on the supervisor of one device within the VSS pair are synchronized to the supervisor of the other device, similar to a 6500 or 4500 with dual supervisors or a 3750 stack.
- Verify software and hardware compatibility with VSS
- Understand and configure Virtual Switch Domains.
- Understand and configure Virtual Switch Links.
- Understand and execute Virtual Switch Conversion.
I recently acquired the use of two Cisco 6504-E switches; each switch is configured with a single VS-S720-10G supervisor module and a WS-X6748-GE-TX 40 port Ethernet module. Both switches are running IOS version 15.0(1)SY2.
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