explorer-monorepo/docs/CCIP_FEE_STRUCTURE.md

CCIP Fee Structure Documentation

Date: 2025-01-12
Network: ChainID 138

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Overview

This document describes the fee structure and payment mechanism for CCIP (Cross-Chain Interoperability Protocol) transactions.

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Fee Configuration

Fee Token

• Token Address: 0x514910771AF9Ca656af840dff83E8264EcF986CA (LINK)
• Network: ChainID 138
• Purpose: Payment token for CCIP fees

Fee Structure

Base Fee

• Amount: 1000000000000000 wei (0.001 LINK)
• Purpose: Base fee for all CCIP messages
• Applies To: All cross-chain messages

Data Fee Per Byte

• Amount: 100000000 wei (0.0000001 LINK per byte)
• Purpose: Fee for message data size
• Calculation: dataFee = dataSize * dataFeePerByte

Total Fee Calculation

totalFee = baseFee + (dataSize * dataFeePerByte)

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Fee Payment Mechanism

Payment Method

Fees are paid in LINK tokens (not native ETH).

Fee Payment Process

1. User Initiates Transfer:

   • User calls bridge contract
   • Bridge contract calculates fee
   • Bridge contract checks LINK balance

2. Fee Payment:

   • Bridge contract transfers LINK to Router
   • Router processes payment
   • Message is sent

3. Fee Verification:

   • Router verifies fee payment
   • Message is queued for processing
   • Oracle network processes message

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Fee Calculation

Current Status: ⚠️ Failing

Fee calculation in scripts is currently failing. This may be due to:

1. Router contract not exposing getFee() function
2. Fee calculation requiring different parameters
3. Fee calculation handled by separate contract

Verification

Script: scripts/verify-fee-calculation.sh

Usage:

./scripts/verify-fee-calculation.sh [amount_eth] [destination_selector]

Example:

./scripts/verify-fee-calculation.sh 0.001 5009297550715157269

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LINK Token Requirements

LINK Token Balance

Bridge contracts need LINK tokens to pay fees:

• Minimum Balance: Enough to cover expected fees
• Recommended: Buffer for multiple transactions

Checking LINK Balance

cast call 0x514910771AF9Ca656af840dff83E8264EcF986CA \
  "balanceOf(address)" \
  <bridge_address> \
  --rpc-url <rpc_url>

Acquiring LINK Tokens

1. Purchase: Buy LINK tokens on exchange
2. Transfer: Send LINK to bridge contract
3. Faucet: Use testnet faucet (if available)

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Fee Estimation

Estimating Fees

For a typical cross-chain transfer:

• Base Fee: 0.001 LINK
• Data Fee: ~0.0001 LINK (depends on message size)
• Total: ~0.0011 LINK per transfer

Factors Affecting Fees

1. Message Size: Larger messages = higher fees
2. Destination Chain: Different chains may have different fees
3. Network Conditions: Fees may vary with network load

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Fee Optimization

Strategies

1. Batch Transfers: Combine multiple transfers to reduce per-transfer fees
2. Optimize Message Size: Minimize data in messages
3. Monitor Fees: Track fee trends and optimize timing

Cost Analysis

• Per Transfer: ~0.001 LINK
• Monthly (100 transfers): ~0.1 LINK
• Annual (1000 transfers): ~1 LINK

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Troubleshooting

Fee Calculation Failing

Symptoms:

• Scripts cannot calculate fees
• getFee() returns 0 or fails

Solutions:

1. Verify Router contract address
2. Check function availability
3. Verify LINK token configuration

Insufficient LINK Balance

Symptoms:

• Transactions failing with insufficient balance
• Fee payment errors

Solutions:

1. Check LINK balance
2. Transfer LINK to bridge contract
3. Verify LINK token address

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Related Documentation

• CCIP Router Configuration
• CCIP Configuration Status
• Complete Task Catalog

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Last Updated: 2025-01-12