Going Beyond the Limitations of Space and Time with Next Generation StackWise® Virtual – Cisco Blogs

First there was Cisco StackWise^® Virtual, providing the ability to virtualize two connected switches into a single virtual switch. Now there’s the next generation of the technology, developed by Cisco IOS XE engineers, with an array of new benefits. The biggest benefit is that this virtualization technology can now run over optical fiber, so switches can be physically located up to thousands of miles away from each other.

What is Cisco StackWise Virtual and Cisco Next Generation StackWise Virtual? What other benefits does it provide? And why is physically stacking switches and hassling with complex cabling so passé?

Read on.

Cisco StackWise Virtual Increases Operational Efficiency

Physical switch stacking solutions use proprietary cables that are laid out in complex configurations and are limited by the length of the cables. Virtualization eliminated the need to physically stack switches on top of each other. Now, through the use of fiber, switches can be located far from each other.

Cisco StackWise Virtual is a network system virtualization technology that pairs two directly connected switches into one virtual switch. To users, the switches look like two separate physical ones. To administrators, they look like one virtual switch with the same configuration and forwarding state.

Switches in a Cisco StackWise Virtual solution increase operational efficiency by using a single control and management plane. Convergence for multicast and failover are much faster. System bandwidth can be scaled with a distributed forwarding plane. And with StackWise Virtual, pioneered by Cisco, administrators can reduce the number of software versions they have to manage by half.

How StackWise Virtual Works

The StackWise solution is an enhancement of Cisco Virtual Switching System (VSS), available on Cisco Catalyst 6500 Series switches. Cisco StackWise Virtual is an inter-chassis system link between two switches that actively forwards traffic (Figure 1) in the StackWise Virtual domain. It enables stack fabric communication over network ports to virtualize the system. The StackWise Virtual connections do not run any network protocol and remain transparent in Layer 2 and Layer 3 network topologies. The active and standby switches support local forwarding that individually perform desired lookups and forward traffic on local links to uplink neighbors.

The ability to cluster two switch chassis together into a single, logical entity provides benefits such as higher availability and scalability and simpler management and maintenance. Cisco StackWise Virtual Link enables a loop-free Layer 2 network topology of Stackwise virtual member switches for both access and core.  The Cisco solution simplifies the Layer 3 network topology by presenting itself as one logical switch, reducing the number of routing peers in the network. The Cisco NSF feature also handles the failure scenarios optimally with the StackWise Virtual SSO so that forwarding is nonstop, even if control plane failover happens.

With solutions at both Layer 2 and Layer 3, Cisco StackWise Virtual provides faster redundancy and failover than other solutions available to enterprises.

Evolution from Data Center Solutions

In the data center, networking vendors have used solutions like multi-chassis link aggregation group (MC-LAG) to virtualize and aggregate multiple network connections. MC-LAG allows ports to terminate on separate chassis to provide redundancy in the event of a link failover. However, implementations of MC-LAG could be associated with other proprietary implementations and therefore implementation can vary from vendor to vendor. And at Layer 3, recomputing occurs, so convergence in the event of a failure is slowed.

Our competitors are pushing the use of the MC-LAG protocol for switch virtualization and stacking in enterprises. But on enterprise campuses, multicast and convergence requirements are much faster and more mission critical. If a link or switch go down, it needs to failover seamlessly and quickly to a different node.

By virtualizing at only Layer 2 to combine the stacked switch brains, Cisco StackWise Virtual provides far superior convergence performance than solutions like MC-LAG or Virtual Router Redundancy Protocol (VRRP), which require failure handling and recomputing at Layer 3.

Also, with the data plane of one node active and the other standby, VRRP provides lower capacity (less data processed) compared to Cisco StackWise Virtual, which maintains an active/active data plane to provide high capacity. With both data planes always active, Cisco StackWise Virtual doubles capacity in the stacking solution, enabling more enterprise access-layer devices (e.g., access points, laptops, phones, sensors) to be supported.

StackWise Virtual Link’s single control plane also helps in failure handling because to the network the stacked switches present as a single entity. If one node fails, another node takes over. The rest of the network is undisturbed.

The Next Generation of StackWise

Recommended for aggregation layers, collapsed aggregation, and core layers for best results, Cisco StackWise Virtual Link can be used over 40G or 100G links to ensure that the distribution of the aggregation switches can be deployed over a long distance. The next generation of the feature in Cisco IOS XE software can run on generic optical fiber, so switches can be located in adjacent buildings or on opposite ends of a continent. For businesses that are becoming overwhelmed with multiple physical switches plugging into the same port, the Cisco StackWise Virtual Link gives them much greater flexibility in switch deployment.

Switches serving an office building with hundreds of users — all accessing Wi-Fi, for example — can now be placed outside of the building, freeing up space and adding flexibility when office configurations change. The new version of StackWise Virtual also offers standards-based node discovery technology, enabling automatic discovery of all nodes on the network. Future release of the Next-Generation Stackwise Virtual could eliminate the restriction of a directly connected network and could connect its member nodes over Layer 2 and Layer 3.

The Next Generation StackWise Virtual best in class logical switch solution features:

• The high availability and flexibility required in campus networks
• A unified management and control plane
• Faster convergence and higher throughput via an active-active data plane
• Greater deployment flexibility with the introduction of a fiber port
• Standards-based discovery
• Future support of StackWise Virtual links in the cloud

So, with Cisco Next Generation StackWise Virtual solution, virtual stacking is set to become a best practice within enterprises. It simplifies network operations with a single control and management plane. It provides faster convergence for multicast and failover. It contributes to a more resilient network where system bandwidth can be scaled across a distributed forwarding plane. And now, system admins are free of the constraints of space and cables to deploy switches anywhere on optical fiber.

Share: