I have been using a sixxs tunnel to provide v6 for ir.bbn.com since January of 2009. There have been a few outages due to problems at the pop (uschi02), but they have been pretty rare. I am pinging the tunnel From nagios, and I don't remember the last time it had a eral failure. Looking at tunnel stats, I see three spikes in loss away from 0 over the last year, but I think several of those were probably brief outages. Keep in mind that tunnel reliability is a combination of my endpoint, their endpoint, and everything in between. So all in all the reliability I've seen has been very good.
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