CODEWITHSUNDEEP
iosnetwork-programmingrouteswifidistributed
matcheek
matcheek

Reputation: 5147

Does iOS MultipeerConnectivity provide routing layer?

I am writing an app that is suppose to work without a connection to mobile carrier and without local WiFi. Each device will act as transmitter, receiver and router. My main challenge so far is that I cannot figure out how exactly MultipeerConnectivity works as documentation on MC is really limited. Apple denied revealing technical specification of MC claiming it's a proprietary network stack, so I have to rely on network sniffers and reverse-engineering which is not the quickest way to figure out how MC works.

Suppose I have 100 devices forming a mesh network in such way that each device is within the range of at least one other device and at maximum three other devices.

Is there any way to send a message from node A to node B that is not within the range of node A without the need to broadcast the message to all other nodes? I mean that message should be properly routed through all other nodes. Does MC include a routing layer too or I have to write it myself?

From what I can see ad hoc delay tolerant wireless networks is still a hot subject in research. These slides on ad hoc delay tolerant wireless network shed more light on the subject as it was a few years ago. And also this paper. Has Apple progressed it much with MC? I cannot really see any way to send a message between nodes not directly connected to each other without flooding. Correct? Mesh network

Upvotes: 3

Views: 305

Answers (1)

Tobi Nary
Tobi Nary

Reputation: 4596

The MCSession Reference states that

Sessions currently support up to 8 peers, including the local peer.

Also, the overview you cited says

In the discovery phase, your app uses a browser object […] to browse for nearby peers[.]

Moreover, the documentation on managing peers manually suggests that all peers in a session must be connected with each other to have them in a session.

This is suggesting that the framework only covers the communication between nearby devices, as in 'reachable by bluetooth or WiFi'. Naturally, those devices do not need complex routing, as they do communicate with each other and the benefit of the framework is simple multicasting between nearby devices, from a programmers' point of view.

As far as your question goes, this is about it - trivially, since all peers an a MCSession have links to each other - there is no routing needed.

This does however, allow you to construct a routing layer pretty easy.

Given your scenario, there will be multiple MCSessions with devices being part of at least one. All devices that are part of more than one MCSession do become routers and interconnect the MCSessions with each other.

The rest of the task should be straight forward; defining a namespace for addressing devices and implementing a routing protocol of your choice.

The old days of the internet, with unstable dialup connections, might be a plus factor for you as the routing protocols in place are rather stable in regards of link loss.

Here are two good starting points for you to make your choice of better fit:

Upvotes: 5

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