AFAIK, Dandelion is not a hard-forking addition to Monero. Meaning, there could still be old nodes in the network that do not support it. How does that work? And what impact do old nodes in the network have on Dandelion?

In general, I am interested in learning more about Dandelion in Monero. If you have any links documenting the implementation I would be happy to know.

1 Answer 1


Dandelion works by setting a flag in the transaction message. If the flag is set, nodes should perform the dandelion steps (ie, decide whether to continue dandelion routing or send to all peers), otherwise not. The existing transaction message format is unchanged.

An old node will not know of that flag, so will understand that message as it used to, and will proceed to send that transaction to all its peers as usual.

This means that if Dandelion supporting nodes are few and far between, the network as a whole will behave much like previously: most txes will get relayed to all peers in short order. Only when most nodes support Dandelion will the effectiveness of Dandelion reach its peak. However, in all cases it will "just work".

  • I dont understand how the transaction message is unchanged if it now includes a dandelion flag? But I guess old nodes will simply ignore this flag and behave as usual? Commented Sep 18, 2020 at 14:12
  • It's a key/value system. No existing keys are removed or changed.
    – user36303
    Commented Sep 18, 2020 at 16:25

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