Re: [RPRWG] control TTL (the 255-station and 2000-km issue)
Anoop,
wrapping nodes always communicate with every other
node anyway. This is necessary for protection
heirarchy to work. Also, given the broadcast
nature of messages to make steering work in under
50 ms, I have no concern over all nodes knowing
that all protection events are done and the ringlets
are healed.
If one waits for the ringlets to be healed
and then killing the packet life is fine. Or
maybe I did not understand your comment.
mike
Anoop Ghanwani wrote:
>
> > > The problem with (3), which you seem to advocate,
> > > is the time gap between the wrap action and the
> > > the distribution/settling of the wrap state information
> > > in other stations. During this time difference, any
> > > and all TTL-strip based frames will be discarded.
> >
> > A good point david, in response please consider the following
> >
> > Never decrement when on the wrong ring. Once the wrap
> > state is left, kill the packet if the ring id
> > is wrong. THus going into wrap does not cause the
> > packets to be prematurely lost. When leaving wrap
> > the packets will be killed once everyone knows
> > the wrap is over.
>
> Mike,
>
> Does everyone on the ring know when a wrap has occured
> and when it heals? I thought wrapping was a local issue
> and only nodes adjacent to the fault know about it.
> In that case, if the node at which wrapping occurs
> detects a heal, and for some reason doesn't pull a wrap
> packet off, it will continue to circulate forever.
> The node can't be dropping wrapped packets forever
> because the wrap could occur somewhere else at
> which time it would be a legal packet for pass-through.
>
> -Anoop
--
Michael Takefman tak@xxxxxxxxx
Manager of Engineering, Cisco Systems
Chair IEEE 802.17 Stds WG
2000 Innovation Dr, Ottawa, Canada, K2K 3E8
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