On Thu, Sep 08, 2011 at 06:59:51PM -0700, Ethan Jackson wrote: > The standard CFM protocol only allows a handful of transmission > rates. This is particularly problematic if you want to support a > transmission rate slower than 100 ms and faster than 1000 ms. > > This patch allows arbitrary transmission rates (between 1 ms and > 65535 ms). It does this by commandeering parts of a reserved > "zero" field in the ccm message. This breaks wire compatibility > with standard 802.1ag implementations, and thus is only supported > in extended mode. > > Bug #7014.
Looks good, thank you. This brings up a design choice that's been on my mind a bit for this series. One design alternative is the one you've chosen, which is to explicitly enable an "extended mode". Another alternative would be to use a standards compliant mode unless options that force the extended mode are configured, e.g. automatically enable extended mode if a nonstandard interval is configured. I usually lean toward the latter, which is why I bring it up, but it seems that there are good reasons to prefer explicit configuration in this case. First, it seems that some users might want extended mode simply to avoid conflicting with standards compliant implementations, even if they are not using extended features. Second, the options that would force the extended mode are kind of hard to describe (you'd have to say something like "if the interval is not exactly 3, 10, 100, 1000, 10000, 60000, or 600000 milliseconds") so users could easily get confused about which mode they've configured. Anyway, I think you've made a good choice, but I bring it up just in case you have further thoughts. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
