🎯 Introduction and Problem Statement

The Tezos blockchain's SeoulNet testnet implements a Data Availability Layer (DAL) that provides additional rewards for validators who successfully attest to data availability. These DAL attestations require specialized infrastructure including properly configured DAL nodes that can receive data shards from the peer-to-peer network and coordinate with baker processes to include DAL attestations in consensus operations.

The subject baker configuration, operating with a substantial stake of 1.25 million ꜩ and utilizing BLS (Boneh-Lynn-Shacham) consensus keys with appropriate companion key associations, was experiencing systematic failures in DAL attestation collection. Despite producing consensus attestations marked as "with DAL" in the baker logs, the TzKT blockchain explorer consistently recorded these as "Missed DAL attestation rewards," indicating a disconnect between the baker's intended DAL participation and the network's recognition of valid DAL attestations.

⚙️ Initial System Configuration

Baker Infrastructure

The baker configuration under investigation operated on a Linux system running Octez v23.0~rc2, specifically configured for the Seoul protocol on SeoulNet testnet. The core configuration comprised a comprehensive setup with both consensus key and companion key associations, which are prerequisites for DAL participation as traditional tz1 (Ed25519) keys cannot participate in DAL attestations.

./octez-baker-PtSeouLo --base-dir /home/mike/.tezos-client \
  --endpoint http://127.0.0.1:8733 \
  run with local node /home/mike/.tezos-node-fresh \
  consensus_key companion_key \
  --liquidity-baking-toggle-vote pass \
  --dal-node http://127.0.0.1:10733

DAL Node Configuration

The initial DAL node configuration was minimal, launched with basic parameters that established RPC communication on port 10733 and connected to the main Tezos node on port 8733. However, this configuration lacked explicit peer configuration and network topology optimization, which would later prove to be critical factors in the connectivity challenges.

./octez-dal-node run --rpc-addr 127.0.0.1:10733 --endpoint http://127.0.0.1:8733

Observed Symptomatology

The primary symptom manifesting in the system was the consistent appearance of "Missed DAL attestation rewards" entries in the TzKT explorer, despite baker logs indicating successful DAL attestation generation. This discrepancy suggested that while the baker was successfully generating DAL attestations with proper key coordination, the underlying DAL data required for valid attestations was not being properly received or processed.

🔍 Diagnostic Methodology and Initial Investigations

Key Association Verification

The initial hypothesis focused on potential issues with the BLS key companion key association, as this is a common source of DAL attestation failures. Investigation of the on-chain delegate status revealed that the companion key association was correctly established, with the active companion key properly linked to the consensus operations. This configuration confirmation eliminated companion key association as the root cause, necessitating deeper investigation into the DAL infrastructure itself.

{
  "companion_key": {
    "active": {
      "pkh": "tz4VbU7whTRT485UoZNX85oybB7j3Hrrt1A3",
      "pk": "BLpk1mVvHEPM2wzunsWrtNSQyb6cBSHTgXpvyyHSoURg7hG8KcVSw2TCsiCmWUuk2dJPkVv2Neq4"
    }
  }
}

DAL Node Process Analysis

Examination of the DAL node logs revealed the critical diagnostic information that would ultimately lead to the solution. The logs definitively demonstrated that the DAL node was consistently receiving zero shards out of the expected number, indicating a fundamental failure in DAL data acquisition from the peer-to-peer network.

Aug 20 16:46:01.343   WARN │ For slots 0 published at level 874708, tz4GVPvRjU74W missed
Aug 20 16:46:01.343   WARN │   shards:
Aug 20 16:46:01.343   WARN │  For slot index 0, 0 shards out of 1 were received

🔬 Network Infrastructure Investigation

Network Connectivity Assessment

Investigation of the DAL node's peer-to-peer connectivity revealed minimal network participation, with only a single peer connection established. When examined in detail, this connection showed an absence of DAL data topics, indicating that while the DAL node was establishing P2P connections, these connections were not facilitating DAL data exchange.

SeoulNet-Specific Bootstrap Configuration

Recognizing that the DAL node required explicit configuration for the SeoulNet testnet environment, the configuration was enhanced with official SeoulNet DAL bootstrap peers. This configuration established explicit connections to the SeoulNet DAL bootstrap infrastructure and configured the DAL node as an attester for the relevant public key hashes.

./octez-dal-node config init \
  --data-dir /home/mike/.tezos-dal-node \
  --endpoint http://127.0.0.1:8733 \
  --attester-profiles tz4GVPvRjU74WK6PvZrvb9jrSnqDykyj7eHc,tz4VbU7whTRT485UoZNX85oybB7j3Hrrt1A3 \
  --peers dal.seoulnet.teztnets.com:11732,dal1.seoulnet.teztnets.com:11732

The enhanced configuration resulted in improved peer connectivity, with peer counts increasing and the connected peers demonstrating active DAL data topic participation. Despite these improvements in peer connectivity and topic subscription, the fundamental issue persisted, with DAL shard reception remaining at zero.

Port Accessibility Constraints

The investigation expanded to examine port accessibility in the residential networking environment. Testing revealed that the standard DAL P2P port (11732) was not accessible from external networks, likely due to residential router firewall policies and ISP port filtering practices common in consumer networking environments. External connectivity testing from a separate network location confirmed this hypothesis, identifying the root cause as the DAL node's inability to receive inbound connections from other network participants due to port accessibility limitations.

# From external network - port 11732 blocked
telnet 162.156.16.87 11732
# Connection timeout or refused

# From external network - port 8080 accessible  
telnet 162.156.16.87 8080
# Connection succeeded

🛠️ Solution Implementation

Port Migration Strategy

Based on the port accessibility analysis, the solution involved migrating the DAL node's P2P communication from the standard port 11732 to port 8080, which demonstrated consistent accessibility across network boundaries. This required reconfiguration of both the public address advertisement and the network binding configuration to enable proper peer discovery and connection establishment.

./octez-dal-node config init \
  --data-dir /home/mike/.tezos-dal-node \
  --endpoint http://127.0.0.1:8733 \
  --attester-profiles tz4GVPvRjU74WK6PvZrvb9jrSnqDykyj7eHc,tz4VbU7whTRT485UoZNX85oybB7j3Hrrt1A3 \
  --peers dal.seoulnet.teztnets.com:11732,dal1.seoulnet.teztnets.com:11732 \
  --public-addr 162.156.16.87:8080 \
  --net-addr 0.0.0.0:8080

Network Service Verification

Post-configuration verification confirmed that the DAL node was properly binding to the new port configuration and that external accessibility was successfully established. The `--public-addr` parameter was configured with the external IP address to enable proper peer discovery and connection establishment, while `--net-addr` was configured to bind to all interfaces on the alternative port.

🏆 Results and Validation

DAL Shard Reception Success

Following the port migration implementation, DAL node logs immediately demonstrated successful shard reception. The transition from "0 shards out of X received" to "got all its shards" represented a complete resolution of the DAL data acquisition issue, marking the first successful DAL operations recorded in the investigation period.

Aug 20 17:41:15.418 NOTICE │ For slots 0 published at level 875535, tz4GVPvRjU74W got all its shards.
Aug 20 17:41:23.297 NOTICE │ For slots 0 published at level 875537, tz4GVPvRjU74W got all its shards.
Aug 20 17:41:27.411 NOTICE │ For slots 0 published at level 875538, tz4GVPvRjU74W got all its shards.

TzKT Network Validation

The definitive validation of the solution's success was provided by the TzKT blockchain explorer, which began recording successful DAL attestation rewards immediately following the implementation of the port migration solution. The explorer data demonstrated the complete transformation from systematic failures to consistent success, providing conclusive evidence that the network was recognizing and processing the baker's DAL attestations correctly.

❌ Missed 46.691892 ꜩ ($38.37) DAL rewards
❌ Missed 46.697715 ꜩ ($38.35) DAL rewards  
❌ Missed 46.691538 ꜩ ($38.27) DAL rewards

✅ +46.692777 ꜩ DAL attestation rewards
✅ +210.19122 ꜩ attestation rewards

Economic Impact Assessment

The resolution of the DAL attestation issue represented a significant economic optimization for the baker configuration. The transformation from systematic DAL attestation failures to consistent success directly translates to substantial reward collection improvement. With a high-stake configuration of 1.25 million ꜩ generating regular attestation opportunities, the successful resolution enables the collection of approximately 46.7 ꜩ per DAL attestation, representing a material improvement in overall baker profitability and optimization of stake utilization efficiency.

📊 Technical Analysis and Implications

Peer-to-Peer Networking in Residential Environments

This investigation highlights the challenges of operating blockchain infrastructure requiring bidirectional peer-to-peer communication in residential networking environments. The successful operation of DAL nodes requires not only outbound connectivity for peer discovery and data request transmission, but also inbound connectivity for DAL shard reception from other network participants. Residential internet service providers commonly implement port filtering and firewall policies that restrict inbound connections on non-standard ports, creating barriers for decentralized infrastructure operation.

Protocol Flexibility and Port Configuration

The Tezos DAL implementation demonstrates appropriate flexibility in port configuration, allowing operators to adapt to their networking constraints while maintaining protocol compatibility. The ability to configure alternative ports for P2P communication enables participation in environments with restrictive networking policies without requiring complex router configuration or enterprise networking infrastructure.

Diagnostic Methodology Effectiveness

The systematic diagnostic approach employed in this investigation proved effective in isolating the root cause among multiple potential failure modes. The progression from high-level symptom observation through intermediate diagnostic indicators to low-level network connectivity testing provided a clear analytical pathway to solution identification, demonstrating the importance of comprehensive investigation methodology in complex distributed system troubleshooting.

🎯 Conclusions and Recommendations

Primary Findings

The investigation conclusively demonstrated that DAL attestation failures in this Tezos SeoulNet baker configuration resulted from network connectivity limitations rather than software configuration issues. The root cause was identified as the inability of other DAL network participants to establish inbound connections to the DAL node due to port accessibility restrictions in the residential networking environment.

Solution Efficacy

The implemented solution, involving migration of DAL P2P communication from port 11732 to port 8080, provided complete resolution of the issue with immediate effect. Post-implementation monitoring confirmed consistent DAL shard reception and successful attestation generation, representing a transformation from zero DAL rewards to optimal DAL participation.

Operational Recommendations

For operators deploying Tezos DAL infrastructure in residential or similarly restrictive networking environments, several key recommendations emerge from this investigation. Port accessibility should be evaluated as part of initial deployment planning, with particular attention to the bidirectional communication requirements of DAL participation. Alternative port configuration should be considered proactively when standard ports demonstrate accessibility limitations, with ports commonly used for web traffic often maintaining broader accessibility. Network environment differences should be considered when replicating configurations across different platforms or locations, as identical software configurations may require networking adaptations based on local infrastructure constraints.

Quantified Results

Knowledge Contribution

This investigation contributes valuable insights to the Tezos baker community and blockchain infrastructure operations more broadly. The identification of residential networking constraints as a significant impediment to DAL participation provides important operational guidance for decentralized infrastructure deployment. The successful demonstration of alternative port configuration for DAL P2P communication establishes a viable pathway for baker operations in constrained networking environments, enabling broader participation in DAL rewards collection without requiring enterprise networking infrastructure.