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Wireless Controller Redundancy with No Client Reauthentication Needed

July 12, 2013 at 5:00 am PST

Last fall, I blogged about No SSID Outage or Access Point Stateful Switchover introduced with the AireOS 7.3 release whereby if your wireless LAN Controller fails due to some hardware failure, thousands of Access Points fail over sub-second to the standby controller! This is possible due to continuous synchronization of CAPWAP states, Configuration Changes, Radio Channel and Power, Roaming Keys and Access Point licenses between the two Controllers. This means even if the administrator changes the configuration, channel plans or the clients roam and the primary controller fails; the Access Points will simply fail over in a stateful fashion to the secondary. In this blog, I will share details on the upcoming enhancements to High Availabilty with the 7.5 release.

In the upcoming AireOS 7.5 release, we take High Availability to the next level with two critical enhancements.

1. Today, after Access Points fail over from the primary to the standby controller, each client tries to re-authenticate and the standby controller then checks against its CCKM database whether the client has already authenticated. At the rate of several tens of authentications per second, it can take anywhere from zero to a few hundred seconds for the tens of thousands of clients that are connected to a controller to re-authenticate. The client stateful essentially eliminates this downtime with sub-second failover. Thus the total downtime that any user running a voice-call or Citrix session experiences is 2-3 seconds that the application requires to reconnect.

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IPv6 Just Works: Cisco Live London Dual-Stack Network

Another year, another CiscoLive. This was the last year in the London venue, and since it was the third time we did it, we had a chance to incorporate learning from the previous two years. As a result, I would say the network was quite a success.

The key element of the design, led by Mark McKillop, was the balance between showcasing the latest technology and maintaining the simplicity of the network. This year we had a mixed L2 + L3 core design. This design helped decrease the impact of various parts on each other. The L2 core was in place for the “special-case” requests, which a routing-based infrastructure could not help with. Read More »

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#EngineersUnplugged S2|Eps5-6: #Automation and #KISS, a Double Header!

March 20, 2013 at 11:14 am PST

On Engineers Unplugged this week, we are trying something new, a double edition! First up in Episode 5, VCE’s Jay Cuthrell (@qthrul) and Nick Weaver (@lynxbat) talk shop in terms of Automation and the evolution of Open Source, including GitHub, and the role of Community in Tech solving problems. Amazing discussion with practical guidance on how you can get more involved:

Jay Cuthrell and Nick Weaver take the Community Unicorn Challenge!

Jay Cuthrell and Nick Weaver take the Community Unicorn Challenge!

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Overlay Transport Virtualization

July 24, 2012 at 10:16 am PST

Fresh from the lab, Jimmy Ray takes a question on OTV or Overlay Transport Virtualization.  This layer 2 Data Center Interconnect technology is growing in popularity as deployed on the Nexus 7000 as it promises transparent workload mobility, business resilience and superior efficiency with computing resources. This could be THE technology for those of you overcomplicating your network design or simply not attempting certain architectures for you did not know this could be done.

We featured OTV quite awhile back in one of our earlier Fundamental animations.  See if this also helps you.   Read More »

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