how many htlcs can a lightning channel have pending at a given time

Question

Channels can have pending HTLCs, or even handle multiple payments concurrently. Is there a max number of pending HTLCs a channel can entertain? What is that max, why is it set to that number, and what are potential ramifications of a higher value (is latency a concern?)

Answer 1

483 because the commitment transaction might otherwise become too large if it hits the chain.

Ramifications are:

• blackmail fee attacks (c. F. https://lists.linuxfoundation.org/pipermail/lightning-dev/2020-June/002735.html a similar attack is known as flood and loot)
• possible congestion of channels (right now only if conducted by an attacker but later potentially due to payment delivery and high routing demand on channels.)

To mitigate those attacks currently most nodes have 30 htlcs as a default value.