proxmox/docs/06-besu/RPC_REVIEW_FOR_BESU_DEPLOYMENT.md

Full RPC Review for Hyperledger Besu Permissioned Blockchain

Last Updated: 2026-01-31
Document Version: 1.0
Status: Active Documentation

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Date: 2025-01-20
Purpose: Comprehensive review of RPC configuration for Foundry deployment to Besu
Issues: Connection timeout and "Known transaction" errors

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Executive Summary

Issues Identified

1. Connection Timeout: RPC connection issues causing deployment failures
2. "Known Transaction" Error: Transactions already in pool, not being cleared

Root Causes

• RPC endpoint connectivity issues
• Transaction pool not clearing duplicate transactions
• Possible transaction pool size limits
• Network timeout settings too aggressive

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1. RPC Endpoint Configuration

Current Configuration

• RPC URL: http://192.168.11.211:8545
• Network: Internal (192.168.11.0/24)
• Protocol: HTTP JSON-RPC

Configuration File

• File: smom-dbis-138/config/config-rpc-core.toml
• Type: Core/Admin RPC node configuration

RPC APIs Enabled

rpc-http-api=["ETH","NET","WEB3","TXPOOL","QBFT","ADMIN","DEBUG","TRACE"]

Status: ✅ All required APIs enabled

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2. Besu RPC Node Configuration

Key Settings

Network Settings

• P2P Port: 30303
• RPC HTTP Port: 8545
• RPC HTTP Host: 0.0.0.0 (all interfaces)
• RPC HTTP Timeout: Not explicitly set (default 60s)

Transaction Pool

• TXPOOL API: ✅ Enabled
• Transaction Pool Size: Not explicitly configured
• Transaction Pool Configuration: Default Besu settings

Permissions

• Account Permissioning: Disabled (permissions-accounts-config-file-enabled=false)
• Node Permissioning: Enabled (permissions-nodes-config-file-enabled=true)

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3. Transaction Pool Analysis

"Known Transaction" Error

Cause

• Transaction already exists in validator transaction pools
• Transaction not being cleared after failures
• Transaction pool not synchronized between nodes

Besu Behavior

• Besu tracks transactions by hash
• Duplicate transaction submissions are rejected
• Transaction pool maintains transactions until included or expired

Solutions

1. Clear transaction pool: Restart Besu nodes
2. Use different nonce: Skip to next available nonce
3. Increase gas price: Replace existing transaction
4. Check transaction status: Verify if transaction was actually sent

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4. Network Connectivity Issues

Connection Timeout

Possible Causes

1. Network latency: High latency to RPC node
2. Firewall rules: Blocking connections
3. RPC timeout: Besu RPC timeout too short
4. Node overload: RPC node under heavy load
5. Connection pool: Too many concurrent connections

Diagnosis

• Test ping connectivity to RPC host
• Test port connectivity (8545)
• Measure RPC response times
• Check for network packet loss

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5. Besu Permissioned Network Considerations

Permission Requirements

1. Account Permissioning: Disabled ✅
2. Node Permissioning: Enabled (validators must be allowlisted)
3. RPC Access: Internal network only

Transaction Submission

• Transactions must be properly signed
• Gas price must meet minimum requirements
• Transaction must be from allowed account (if account permissioning enabled)

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6. Transaction Pool Configuration

Besu Default Limits

• Transaction Pool Size: 4096 transactions (default)
• Pending Transaction Limit: 4096 per account (default)
• Transaction TTL: 60 seconds (default)

Configuration Options

# Transaction pool settings (if needed)
tx-pool-max-size=4096
tx-pool-limit-by-account-percentage=1.0
tx-pool-hash-limit=1024

Current Status

• ⚠️ Transaction pool settings not explicitly configured
• Using Besu defaults

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7. Recommendations

Immediate Actions

1. Fix Connection Timeout

# Increase RPC timeout in foundry.toml
[rpc_endpoints]
chain138 = "http://192.168.11.211:8545"

# Use longer timeout in scripts
cast send ... --rpc-url "$RPC_URL" --timeout 30000

2. Clear Transaction Pool

# Option 1: Restart Besu RPC node
sudo systemctl restart besu-rpc-core

# Option 2: Clear transaction pool via admin API
cast rpc admin_removePeer --rpc-url "$RPC_URL" <peerId>

3. Check Transaction Status

# Check if transaction exists
cast rpc eth_getTransactionByHash --rpc-url "$RPC_URL" <txHash>

# Check transaction pool content
cast rpc txpool_content --rpc-url "$RPC_URL"

4. Use Higher Gas Price for Replacements

# Increase gas price to replace existing transaction
cast send ... --gas-price 3000000000  # 3 gwei

Configuration Changes

1. Increase RPC Timeout

# config-rpc-core.toml
rpc-http-timeout=120  # Increase from default 60s

2. Configure Transaction Pool

# config-rpc-core.toml
# Transaction pool limits
tx-pool-max-size=8192
tx-pool-limit-by-account-percentage=0.5

3. Enable Transaction Pool APIs

# Ensure TXPOOL API is enabled
rpc-http-api=["ETH","NET","WEB3","TXPOOL","ADMIN","DEBUG"]

Best Practices

1. Transaction Management

• Always check transaction status before retrying
• Use explicit nonces to avoid conflicts
• Implement retry logic with exponential backoff
• Clear transaction pool if errors persist

2. Network Configuration

• Use stable network connections
• Monitor network latency
• Configure appropriate timeouts
• Use connection pooling

3. Deployment Strategy

• Verify RPC connectivity before deployment
• Check transaction pool status
• Use appropriate gas prices
• Monitor transaction confirmations

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8. Diagnostic Commands

RPC Connectivity

# Test basic connectivity
cast chain-id --rpc-url http://192.168.11.211:8545

# Test RPC response time
time curl -X POST -H "Content-Type: application/json" \
  --data '{"jsonrpc":"2.0","method":"eth_chainId","params":[],"id":1}' \
  http://192.168.11.211:8545

Transaction Pool Status

# Check transaction pool status
cast rpc txpool_status --rpc-url http://192.168.11.211:8545

# Check pending transactions
cast rpc txpool_content --rpc-url http://192.168.11.211:8545

# Check specific account transactions
cast rpc eth_getTransactionCount <address> pending \
  --rpc-url http://192.168.11.211:8545

Transaction Verification

# Check if transaction exists
cast rpc eth_getTransactionByHash --rpc-url "$RPC_URL" <txHash>

# Check transaction receipt
cast rpc eth_getTransactionReceipt --rpc-url "$RPC_URL" <txHash>

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9. Foundry Configuration

Recommended foundry.toml Settings

[rpc_endpoints]
chain138 = "http://192.168.11.211:8545"

[rpc_endpoints.chain138]
timeout = 30000  # 30 seconds

Deployment Script Best Practices

# Use explicit timeout
cast send ... --rpc-url "$RPC_URL" --timeout 30000

# Check transaction status before retrying
TX_HASH=$(cast send ... --rpc-url "$RPC_URL")
cast receipt "$TX_HASH" --rpc-url "$RPC_URL"

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10. Action Items

High Priority

1. ✅ Review RPC configuration (THIS DOCUMENT)
2. ⏳ Increase RPC timeout settings
3. ⏳ Implement transaction status checking
4. ⏳ Add retry logic with backoff

Medium Priority

1. ⏳ Configure transaction pool limits
2. ⏳ Monitor network connectivity
3. ⏳ Implement connection pooling
4. ⏳ Add comprehensive error handling

Low Priority

1. ⏳ Optimize transaction pool settings
2. ⏳ Implement transaction deduplication
3. ⏳ Add transaction pool monitoring
4. ⏳ Create deployment health checks

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11. Conclusion

Current Status

• ✅ RPC APIs properly configured
• ⚠️ Connection timeout issues present
• ⚠️ "Known transaction" errors occurring
• ⚠️ Transaction pool management needed

Next Steps

1. Implement timeout fixes
2. Add transaction status checking
3. Improve error handling
4. Monitor transaction pool status

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This review identifies the root causes of deployment issues and provides actionable recommendations for fixing them.