What is the incentive for a peer to broadcast the transactions it received?

[GingerMoon]

I understand why a peer broadcast the block to other peers, but what is the incentive for a node to broadcast the transactions it received?
What if a peer doesn't broadcast the transactions it received?

 

[torusJKL]

I think non-mining nodes do it without any incentive.

With block propagation protocols like Xthin and Graphene mining nodes have an interest that all other mining nodes know the tx set they will include in their next block in advance.
So that their block is accepted as fast as possible once anounced.

 

[theZerg]

good question. Note that a miner would have an incentive to NOT broadcast a high-fee paying tx, so he can mine it himself. The additional orphan chance due to a slightly higher block transmitted size would not be greater than the tx fee.

 

[AdrianX]

What if a peer doesn't broadcast the transactions it received?

people can customize their implementation to deviate from the default, most don't, but by default, BU relays most transactions, by contrast, ABC does not relay transactions when the fees are low (a policy inherited by forking a later version of Core)

We know what happens, the transaction eventually finds the single node mining with BU, and in time it confirms the transaction.

it's actually in the best interest of the person receiving the transaction to ensure that the transaction is broadcast to a miner, most exchanges and high volume relay nodes ensure they are connected to the miners.