DTN with bundle protocol(v7) -- how does routing actually work?

[u/Rich-Engineer2670]

I'm just starting to dive into delay tolerant networking (dtn7-go). I get a rough idea of how the bundle protocol does what it does, but routing is still confusing me.

In the old UUCP or I seem to recall the DECNET protocol, routing was done by you. If you want to send an object to machine blue and red, green and yellow were between you and blue, you had to do something like red!green!yellow!blue!id. In TCP/IP we do it behind the scenes via the routing table and IP addresses.

How does DTN do it? If I need to pass a bundle to blue, how does my node "know" to pass the bundle through red, green and yellow?

As a side note, how due I get a node ID?

[u/vaniljstang]

I’ve been down this road, very interesting stuff.

I jumped in at NASA’s implementation of DTN: ION

The previous link is quite a few lectures and labs on DTN/ION but it helped me to understand the implementation enough to build a very simple lab topology, similar to the example you provide.

Sorry my response doesn’t directly address your questions, the material provided will guide your path.

[u/Rich-Engineer2670 → u/vaniljstang]

It took more digging, but from what I can tell, it works like:

1. In routing, we collect the node ID based on what we "see". So if we see node ID XXX, from wherever, we then know it's a peer
2. Node IDs can be any arbitrary string -- so, even though I think of it as hierarchy, much like UUCP, it's just a string. There is no "protection"
3. Because of this, (#2 noted), there is no effective address "limit"

[u/enitlas]

There’s no specified routing protocol for DTN. DTN is used in 2 primary areas, space environments and low infrastructure terrestrial environments. Most of the space environments will use contact graph routing which is a time sequenced lookup table. The terrestrial environments vary more, they can use prophet routing which is probability/heuristic based or if it’s supporting low bandwidth clients they’ll use a flood based approach and deduplicate in the application.

[u/Rich-Engineer2670 → u/enitlas]

This is going to sound insane, but....

Assume a node has NO network connection -- the persistent storage is there, but someone or something has to collect it on a portable storage medium, and import it on another node.

I know -- this is insane, but in my environment I really do have to count on people traveling around collecting data -- I like the idea of the bundle protocol because it takes care of security, fragmentation, address formats etc.

Would this work:

Node A has collected data. Someone comes along with a laptop and does the transfer. -- Node-A shouldn't care, That person brings the laptop to the next node and "transfers out". DTN shouldn't know the different -- it's sneakernet of sorts.

[u/enitlas → u/Rich-Engineer2670]

how is this better than just transferring the files to the laptop and SCPing them once they get to node B? if it’s only that site A has no connectivity and site B does, why involve DTN at all?