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Cisco Introduces Virtual Switching to Bond Chasses Together

Posted by Andy Dornan
November 06, 2007

Tags: 10-Gig Ethernet, Ethernet, catalyst 6500s together, switches, switching, virtualization, Cisco, Data Networking & Management, Data Protection, Data Security, Electronics, Hardware, Management, Networking, Networking and Telecom, Other, Security Appliances and Hardware, Servers & Storage, Technology, Windows 3.1 and older

Channel: Other, Networking & Mgmt, Servers & Storage, Data Protection

Cisco Systems today announced new technology for two of its modular switch families: the high-end Catalyst 6500 and mid-range Catalyst 4500. The company is promoting them both as the next phase of the Campus Communications Fabric, a strategy it announced in April, but this is just branding. The two have no real connection other that they're both switches and both launched on the same day.
From a technical perspective, the most interesting is the VSS (Virtual Switching System), an upgrade for the 6500. Enabled via a new Supervisor Engine module, it enables two 6500 chasses to be bonded together via 10-Gig Ethernet so that they act as one, share a single IP address, MAC address and virtual backplane. This can make management simpler (half as many switches to deal with) and cut a routing hop out of a network.

The two switches can even take advantage of each other's service modules for features like routing, application acceleration and wireless management, but there's a big catch here. Although the switches appear to have a single backplane, they're still only physically connected by a 10-Gbps wire. Each individual 6500 chassis has a backplane of up to 256 Gbps (and at least 32 Gbps), so the 10-Gig Ethernet could easily be a bottleneck if a lot of traffic from one switch needs to be processed by a module on the other.
For this reason, the most immediate beneficiaries of VSS are likely to be Cisco customers who already have two identically-configured 6500 chasses, one sitting idle as a backup. Cisco says that this can effectively double switching capacity, allowing the spare switch to be used in production, though as always there's a tradeoff: With no spares, losing a switch will mean a real reduction in available bandwidth.
The 4500 series gets an across-the-board upgrade with four new chassis options and three new line cards, collectively known as the 4500-E and based on new "CenterFlex" ASICs. They boost total switching capacity to 24 Gbps per slot and are fully backward-compatible with previous 4500 modules and chasses, though the new gear is needed for the higher bandwidth and the new features.

The most notable new feature is better PoE support, with all of the 48 ports on the new 10/100/1000 modules offering enough power (about 18 W) to run Cisco's dual-radio 802.11n access points. Cisco also offers a Premium PoE option that boosts power to 30 W, enough for an IP video camera, though this will require a future software upgrade and only work for half of the available ports.

RELATED LINKS Cisco's 802.11n AP Announcement Confirms and Surprises The most unexpected element of Cisco's news is that they will be able to power their dual-radio 802.11n access points using selected models from their Catalyst line of switches.

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