The maximum contest window, a critical parameter in this setup, is by default set to 2016 blocks. This value, however, can be adjusted by modifying the bitcoin.maxlocaldelay setting within the lnd.conf file, offering flexibility to users based on their security requirements or preferences.

The negotiation of these timelocks occurs implicitly during the channel opening procedure through the exchange of open_channel and accept_channel messages. These messages include a to_self_delay field that specifies the timelock duration. This mechanism allows either participant to reject the proposed channel if the suggested timelock does not align with their expectations. An error message indicating an unacceptable timelock provides feedback, enabling parties to iteratively find a mutually agreeable duration.

When it comes to imposing timelock constraints, the approach varies depending on whether one is initiating the channel opening or responding. Initiators specify their preferred timelock through RPC arguments during the channel opening, whereas responders rely on the configuration specified in lnd.conf or default to a linear scale based on channel size if no configuration is provided. For those seeking greater control over these settings, LND offers the option to utilize a ChannelAcceptor, allowing for dynamic decision-making regarding timelock constraints.

It's important to note that there is no requirement for the timelock values to be symmetric between the two parties involved in the channel. This aspect underscores the importance of clear communication and negotiation to ensure both parties are satisfied with the timelock settings, preventing potential disagreements from hindering the establishment of a channel.

For further technical details and insights into the protocol mechanics and LND's behavior regarding timelocks and channel negotiations, interested readers can refer to the official documentation available at Lightning Network Specifications, LND Funding Manager, and Channel Acceptor Documentation, among other resources. These documents provide a comprehensive overview of the procedures and options available to participants of the Lightning Network, ensuring a robust and flexible platform for digital transactions.