Re: [IPsec] Issue #177. (was: HA/LS terminology)

+1
I agree with Dan.

On Wed, Mar 24, 2010 at 1:16 PM, Dan Harkins <dharkins@lounge.org> wrote:

>
> On Tue, March 23, 2010 7:24 pm, Yoav Nir wrote:
> >
> > On Mar 23, 2010, at 6:05 PM, Dan Harkins wrote:
> >
> >>
> >>  Hi,
> >>
> >>  "hot standby" implies a box sitting ("hot") twiddling its thumbs doing
> >> little but waiting for another box to fail ("standby"). It's the VRRP
> >> model.
> >
> > And that's exactly what I want to describe. Well, not twiddling its
> > thumbs. The standby is synchronizing state with the active member, but
> > it's not doing any IKE or IPsec
>
>   Well don't use such a limiting term to describe a behavior that is
> not so limited. Not all HA is that small subset you want to describe.
>
> >>  There is a HA model which supports dynamic load balancing as well as
> >> active session failover. Nodes in such a cluster are not "standby". They
> >> each have loads that they can shed and add to based upon some heuristic.
> >> A neat attribute of such a system is that an IPsec SA can be established
> >> on node A, move to node B after a while, and come back to A some time
> >> later without any actual node failure. State moves around to keep the
> >> cluster balanced.
> >
> > Failure is just used as an example of why a certain SA failed over to
> > another member. It is by no means the only reason. Still, what you are
> > describing is a model that provides both high-availability and load
> > balancing, and that is the reason we're moving away from calling the
> first
> > model "high availability".
>
>   Of course it's not the only reason. But you're missing the point. The
> point is that the reason doesn't matter! You want to describe a particular
> reason-- the "master" crashed and all state went over to the "hot
> standby"--
> not the generic concept of state moving.
>
>  So don't call it "high availability" then. But "hot standby" is worse.
>
> >>  I would very much prefer "session failover" to "hot standby" and a
> >> mild preference of "load balancing" over "load sharing". An HA model
> >> doing VRRP could be termed "session failover" but the HA model described
> >> above really can't be called "hot standby". And load can be shared but
> >> just sharing a load can result in a mis-balanced cluster if sessions on
> >> one node terminate naturally and it sits doing little while another node
> >> whose sessions haven't terminated is huffing-and-puffing. Balancing can
> >> imply sharing but not vice versa.
> >
> > "Session failover" sounds to me more like a description of an event than
> a
> > type of cluster.
>
>   So what? Are you suggesting that a type of cluster that is not a
> "hot standby" is not worthy of terminology in IPsecME?
>
>  Your term is severely limiting. I like "session failover". If you don't
> then come up with a term that generically describes HA and not the
> particular style of HA that you are accustomed to.
>
>  Dan.
>
>
>
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