How do you add multiple IP addresses/interfaces to an endpoint?

[mirjak]

what happened if you add multiple addresses or interfaces to an endpoint: Does it overwrite the existing one or not?

[MaxF12]

I would say that it does not overwrite but simply add to a list of addresses. This is, among other things, because for a Listen() the remote endpoint can be used to filter incoming connections and I don't think it makes much sense to only be able to constrain it to a single address.

[philsbln]

I agree with @MaxF12 – but we should really make this explicit

[mirjak]

Discussion at interim: Clarification is needed. add() during preconnection will overwrite, and add() cannot be used in connection state. Also add a note in the text that e.g. specifying a specific IP address might restrict mobility or use of multiple paths and could cause the connection to fails when the IP address goes way rather than enabling some handover. Still open: Do we need a way to add of multiple addresses in the first place? This is used for filtering remote IP addresses for listener for multicast.

[tfpauly]

The current API text doesn't use "add", but rather "with...":

RemoteSpecifier := NewRemoteEndpoint()
RemoteSpecifier.WithIPv4Address(192.0.2.21)
RemoteSpecifier.WithPort(443)

It also implies that multiple is already allowed:

Multiple endpoint identifiers can be specified for each Local Endpoint and
Remote Endpoint.  For example, a Local Endpoint could be configured with two
interface names, or a Remote Endpoint could be specified via both IPv4 and
IPv6 addresses. These multiple identifiers refer to the same transport
endpoint.

How does that line up with the comment about add(), and having that replace?

[renghardt]

As far as I can see, in the API draft we currently have add() for Properties and Security Parameters where each new add() overwrites the value for the old one.
So if we change this to add(), probably IP addresses should work the same.
But can't we just allow add() with a list of IP addresses instead of just with a single IP address?

[tfpauly]

• Allow adding an alias endpoint to an endpoint
• Any one endpoint has at most one hostname
• Any one endpoint has at most one port/service (if you need more, add an alias)
• Any one endpoint has at most one address

If you need multiple source-specific multicast filters, use multiple connection objects