We just got a couple of new 6509's, and they shipped with catos
6.4.23. This didn't make sense to me since 8 has been shipping for a few years. Yet, I checked cisco's download site, and sure enough
6.4.23 was released December 21, 06, and 8.5.8 was released December
5, 2006. The image size for 6.4 is quite a bit less that 8.5, but new switches came with 6.4. Is 6.4 a new train or something?