Mobile IP and Upper Layer Interaction MOBOPTS WG, IETF 66 Vijay Devarapalli Rajeev Koodli

Problem Mobile node wants to change its home address or start using a different home address e.g. for privacy reasons What happens to existing sessions using the old home address? How does Mobile IP know if there are existing sessions on the old home address? How is the correspondent node informed? Is it ok to expect sessions to break when the home address changes?

Reachability and change in HoA Once MN starts using the new HoA how is it reachable at the new HoA?

Possible solutions Existence of a binding cache entry at the CN Check if the CN has a binding cache entry for the MN’s old home address If there is no binding cache entry, then there is no session with the CN If there is a binding cache entry, then need to inform the CN But the existence/lack of a binding cache entry does not imply there is/isn’t a session BCE exists but no active traffic Traffic reverse tunneled through the home agent

Possible solutions Use old HoA and new HoA simultaneously for a while The MN shouldn’t change the HoA abruptly Let existing sessions continue with the old HoA Start new sessions with the new HoA But how does Mobile IP know there are existing sessions?

Detecting existing sessions The mobile node records the timestamp of the last packet sent using a particular binding update list entry But this doesn’t accurately say if there is an existing session The mobile node keeps track of all the sockets that were opened with a particular home address May need to formalize an interface for this

Detecting existing sessions Look through all the Protocol Control Blocks (PCB) for active sessions with the old home address Does not work for UDP connections on some operating systems. Works only for TCP

Reachability at the new HoA MN wants to be reachable at the new HoA FQDN is used to reach the mobile node The MN can use the DNS update mechanism described in the bootstrapping work If some other identifier is used to reach the mobile node, we need to figure out how to update the identifier to HoA mapping

Changing a psuedo-HoA There are solutions that describe using a psuedo-HoA instead of the real HoA in route optimized traffic Changing the psuedo-HoA is easy HoA to psuedo-HoA mapping is stored in the binding update list at the MN and the binding cache entry at the CN Need to update these mappings

Run Shim6 over MIPv6 Shim6 allows one to use multiple HoAs at the same time Not suitable for changing home addresses All HoAs not known initially Can still be done with shim6 But requires shim6 support on the CN