- So clearly I missed what you meant.
- >
> I would expect this would cause the routing algorithm to be told about
- >
> the failure and to find an alternative path involving the same or an
- >
> alternative map entry.
- Suppose there is a failure of an intermediate router, between two
- domains in the DFZ. They know nothing of mapping/unmapping, and mapping
- knows nothing of them. This is handled by BGP right now. Are you
- suggesting that changes in BGP paths across the DFZ should be
- communicated to the mapping points, or perhaps to the mapping
- distribution/discovery system, so that they can change their preferred
- mappings?
- Or, suppose there is a failure of a de-mapping point (ETR). At least in
- LISP, that will very probably not be seen in mainstream BGP -- its RLOC
- is just a single address in PA space. Any failure here is not a concern
- of mainstream routing, and will be taken care of in the mapping system.
- On 3/25/08 5:54 PM, Brian E Carpenter allegedly wrote:
- > On 2008-03-26 03:49, Xu Xiaohu wrote:
- >
> How about having the authoritative ETR to update the status of the EID-
>RLOC
- >
> mapping in the mapping system automatically according to the connectivity
- >
> between the ETR and the site network, while having the routing system to
- >
> determine the reachability of the ETR?
- >
- > However, we want to avoid map flapping by design (you will remember
- > that BGP4 route flapping was a big problem).
- >
- > I would set a quite different timescale for status updates
- > in the mapping system - if we followed your suggestion, I would
- > suggest that a loss of connectivity should persist for
- > a long time, maybe 30 minutes, before the ETR changes the
- > map. I'd expect BGP to handle any outages on a shorter timescale.
- > If we set the timers in the mapping system to the same order
- > of magnitude as those in the routing system, we're likely
- > to see some horrible interactions between map flapping
- > and route flapping.
- The current LISP trick is the "locator reachability" bits piggybacked on
- data packets. You can separate operational changes (the kind subject to
- flaps) from configuration changes. There is no need for mappings to
- change due to operational problems, nor timers etc. I still don't
- understand why you think BGP would be involved. Are you presuming that
- we are going to run BGP between nodes that are not globally routed? Why
- would DFZ BGP even know that an ETR was dead?
Perhaps it would be a good approach to set, for each mapping entry, a
timer and let each end host (or ETRs) send mapping updates to the mapping
system?
Hongbin