We all have been listening to virtual networks for quite a sometime now and today is our turn to discuss about VSS. So, lets have a look at VSS and try to understand what is it and how does it works.
What is VSS ?
VSS is network system virtualization technology that pools multiple Cisco Catalyst
6500 Series Switches into one virtual switch, increasing operational
efficiency, boosting nonstop communications, and scaling system
bandwidth capacity to 1.4 Tbps. Switches would operate as a single
logical virtual switch called a virtual switching system 1440 (VSS1440). VSS formed by two Cisco Catalyst 6500 Series
Switches with the Virtual Switching Supervisor 720-10GE.
In a VSS, the
data plane and switch fabric with capacity of 720 Gbps of supervisor
engine in each chassis are active at the same time on both chassis,
combining for an active 1400-Gbps switching capacity per VSS. Only one
of the virtual switch members has the active control plane. Both chassis
are kept in sync with the interchassis Stateful Switchover (SSO)
mechanism along with Nonstop Forwarding (NSF) to provide nonstop
communication even in the event of failure of one of the member
supervisor engines or chassis.
So, In short - The Cisco Catalyst 6500 Series Virtual Switching System (VSS) 1440 allows for the merging of two physical Cisco Catalyst 6500 Series Switches together into a single, logically managed entity. Figure 1 graphically represents this concept where you can manage two Cisco Catalyst 6509 chassis as a single, 18-slot chassis after enabling Cisco Virtual Switching System.
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| Cisco 6500 Virtual Switching System (VSS) |
What are the benefits of using VSS ?
VSS
offers superior benefits compared to traditional Layer 2/Layer 3
network design. VSS increases operational efficiency by simplifying the network, reducing switch management overhead by at least 50 percent. Single point of management, IP address, and routing instance, Single configuration file and node to manage and you wont have to configure two switches with identical policies and other config. It eliminates the requirement for HSRP, VRRP or GLBP and you have to use just one IP address instead of three used with any FHRP.
Multichassis EtherChannel
(MEC) is a Layer 2 multipathing technology that creates simplified
loop-free topologies, eliminating the dependency on Spanning Tree
Protocol, which can still be activated to protect strictly against any
user misconfiguration and with X2-10GB-ER 10 Gigabit Ethernet
optics, the switches can be located up to 40 km apart.
Interchassis stateful failover results in no disruption to applications
that rely on network state information (for example, forwarding table info, NetFlow, Network Address Translation [NAT], authentication, and authorization). VSS eliminates L2/L3 protocol reconvergence if a virtual
switch member fails, resulting in deterministic subsecond virtual
switch recovery.
By activating all available Layer 2 bandwidth across redundant Cisco
Catalyst 6500 Series Switches with automatic, even load sharing. Link
load sharing is optimized because it is based on more granular
information, such as L2/L3/L4 parameters, unlike virtual LAN
(VLAN)-based load balancing in Spanning Tree Protocol configuration.
Also, I had found a video for VSS -
More information about Virtual Switching System (VSS) can be found here