**Best-effort delivery**


### Lack of admission control
I will do my best but router cannot guarantee anything about performance
because packet transmit through a lot of routers
so router does not reject any packet and there is no reject algorithm. So it might be full of buffer and only rate negotiation algorithm. there is upper layer’s algorithm that reject like admission algorithm  
If we can’t afford buffer, we just drop the packet (packet drop). We implements bunch of algorithms for that like random drop


### There is no priority
Internet itself does not provide priority. They tried a long times but hard to implement which satisfy through all architecture of internet. 




> [Best-effort delivery](https://en.wikipedia.org/wiki/Best-effort_delivery)





