Greenplum Interconnect: Supported Linux Bonding Modes on RHEL 9

Products

• VMware Tanzu Greenplum

Issue/Introduction

The Greenplum Database interconnect relies heavily on UDP traffic (UDPIFC) and requires a stable and redundant network for query performance and reliability. In production environments, redundant NICs and switch configuration are strongly recommended.

This article clarifies which Linux bonding modes are supported and recommended for Greenplum Database 7.x running on RHEL 9.

Environment

Greenplum supported versions

 RHEL 9

Resolution

Supported Bonding Modes (RHEL 9)

• Active-backup (mode=1):
  Safest and recommended when simplicity and stability are priorities. Provides redundancy without load balancing and avoids packet reordering.
• Requires no switch-side configuration
• Ensures automatic failover if a NIC fails
• 802.3ad / LACP (mode=4):
  Supported and preferred for higher throughput if the switch-side configuration is correct. Provides both redundancy and load balancing of interconnect traffic.
• Requires switches configured with LACP port groups
• Recommended to use xmit_hash_policy=layer3+4 for flow distribution
• MTU must be aligned across NICs, switches, and cluster hosts
• Not Recommended Modes:
• balance-rr (mode=0) and balance-tlb (mode=5) can cause packet reordering and drops.
• These issues negatively affect UDP-heavy workloads such as Greenplum’s interconnect, leading to query delays or failures.

LACP Configuration Requirements

When using bonding mode 4 (802.3ad LACP):

• Enable LACP on the switch ports connected to the bonded NICs.
• Set xmit_hash_policy=layer3+4 for flow-based traffic distribution.
• Ensure consistent MTU sizes across all interfaces and switches.
• Validate negotiation and distribution:

Troubleshooting and Validation

Before standardizing bonding modes across a Greenplum cluster:

• Check bonding status:
• Validate NIC drivers and firmware for RHEL 9 compatibility
• Basic network tests: ping, iperf3, ethtool
• Greenplum-specific validation:
• Use gpcheckperf to validate bandwidth, latency, and packet loss thresholds
• Run gpcheck for cluster-level verification

Additional Information

Related Documentation

• Configuring Your Systems – OS networking tuning, MTU, bonding
• Architecture Overview – Greenplum interconnect design
• Interconnect Configuration Parameters – gp_interconnect_type, MTU settings
• gpcheckperf Utility Reference– Testing and validation
• Ports and Protocols – Interconnect ports used by Greenplum
• Release Notes – Interconnect updates, RHEL 9 support
• Network Troubleshooting Guide for Tanzu Greenplum – Step-by-step diagnosis
• Best Practices Guide
• Reference Guide