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Version: v2.0.0

Interchain Security Parameters

The parameters necessary for Interchain Security (ICS) are defined in

  • the Params structure in proto/interchain_security/ccv/provider/v1/provider.proto for the provider;
  • the Params structure in proto/interchain_security/ccv/consumer/v1/consumer.proto for the consumer.

Time-based parameters​

ICS relies on the following time-based parameters.

ProviderUnbondingPeriod​

is the unbonding period on the provider chain as configured during chain genesis. This parameter can later be changed via governance.

ConsumerUnbondingPeriod​

is the unbonding period on the consumer chain.

info

ConsumerUnbondingPeriod is set via the ConsumerAdditionProposal governance proposal to add a new consumer chain. It is recommended that every consumer chain set and unbonding period shorter than ProviderUnbondingPeriod


Example:

ConsumerUnbondingPeriod = ProviderUnbondingPeriod - one day

Unbonding operations (such as undelegations) are completed on the provider only after the unbonding period elapses on every consumer.

TrustingPeriodFraction​

is used to calculate the TrustingPeriod of created IBC clients on both provider and consumer chains.

Setting TrustingPeriodFraction to 0.5 would result in the following:

TrustingPeriodFraction = 0.5
ProviderClientOnConsumerTrustingPeriod = ProviderUnbondingPeriod * 0.5
ConsumerClientOnProviderTrustingPeriod = ConsumerUnbondingPeriod * 0.5

Note that a light clients must be updated within the TrustingPeriod in order to avoid being frozen.

For more details, see the IBC specification of Tendermint clients.

CCVTimeoutPeriod​

is the period used to compute the timeout timestamp when sending IBC packets.

For more details, see the IBC specification of Channel & Packet Semantics.

danger

If a sent packet is not relayed within this period, then the packet times out. The CCV channel used by the interchain security protocol is closed, and the corresponding consumer is removed.

CCVTimeoutPeriod may have different values on the provider and consumer chains.

  • CCVTimeoutPeriod on the provider must be larger than ConsumerUnbondingPeriod
  • CCVTimeoutPeriod on the consumer is initial set via the ConsumerAdditionProposal

InitTimeoutPeriod​

is the maximum allowed duration for CCV channel initialization to execute.

For any consumer chain, if the CCV channel is not established within InitTimeoutPeriod then the consumer chain will be removed and therefore will not be secured by the provider chain.

The countdown starts when the spawn_time specified in the ConsumerAdditionProposal is reached.

VscTimeoutPeriod​

is the provider-side param that enables the provider to timeout VSC packets even when a consumer chain is not live. If the VscTimeoutPeriod is ever reached for a consumer chain that chain will be considered not live and removed from interchain security.

tip

VscTimeoutPeriod MUST be larger than the ConsumerUnbondingPeriod.

BlocksPerDistributionTransmission​

is the number of blocks between rewards transfers from the consumer to the provider.

TransferPeriodTimeout​

is the period used to compute the timeout timestamp when sending IBC transfer packets from a consumer to the provider.

If this timeout expires, then the transfer is attempted again after BlocksPerDistributionTransmission blocks.

  • TransferPeriodTimeout on the consumer is initial set via the ConsumerAdditionProposal gov proposal to add the consumer
  • TransferPeriodTimeout should be smaller than BlocksPerDistributionTransmission x avg_block_time

Slash Throttle Parameters​

SlashMeterReplenishPeriod​

exists on the provider such that once the slash meter becomes not-full, the slash meter is replenished after this period has elapsed.

The meter is replenished to an amount equal to the slash meter allowance for that block, or SlashMeterReplenishFraction * CurrentTotalVotingPower.

SlashMeterReplenishFraction​

exists on the provider as the portion (in range [0, 1]) of total voting power that is replenished to the slash meter when a replenishment occurs.

This param also serves as a maximum fraction of total voting power that the slash meter can hold. The param is set/persisted as a string, and converted to a sdk.Dec when used.

MaxThrottledPackets​

exists on the provider as the maximum amount of throttled slash or vsc matured packets that can be queued from a single consumer before the provider chain halts, it should be set to a large value.

This param would allow provider binaries to panic deterministically in the event that packet throttling results in a large amount of state-bloat. In such a scenario, packet throttling could prevent a violation of safety caused by a malicious consumer, at the cost of provider liveness.