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Re: [leshan-dev] LeshanClient and IP address changes
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Hi Kiran,
> 1. Does users of Leshan project have to listen for IP changes and send
> a register request again ?
The LWM2M spec indicates, that a LWM2M server should assume that a client is reachable under the IP address used for sending its "Register" request. Thus, if the client's IP address changes, it should send an "Update Registration" request in order to provide the LWM2M server with its new IP address.
> 2. If I am behind a router firewall ( outgoing allowed ) with static
> IP, do I have to listen for network changes ( like router restart ) and
> register again ( for hole punching in router ) ?
I assume you are talking about a NAT firewall, i.e. the router has a single public IP address and translates between private (internal) IP addresses and this single public IP address.
Most of such firewalls/routers will create a mapping entry in their NAT table when you send an outbound UDP packet to the LWM2M server, thus enabling outbound and inbound UDP traffic between your (internal) LWM2M client and the LWM2M server (external). This mapping entry will usually only exist for a limited time only if no data is exchanged (for UDP this is often not more than several minutes). Thus, in order to keep the mapping entry alive (and thus allow for inbound traffic originating from the LWM2M server), you should update the LWM2M registration every few minutes. The exact frequency of updates required to keep the mapping alive depends on your particular router/firewall though.
Regards,
Kai
