> Source: [sk184390](https://support.checkpoint.com/results/sk/sk184390)

# sk184390 - BGP IPv6 Bidirectional Forwarding Detection (BFD) sessions drop during ClusterXL failover

| Property | Value |
|----------|-------|
| Solution ID | sk184390 |
| Date Created | 2025-12-14 |
| Last Modified | 2025-12-29 |
| Technical Level | Advanced |
| Products | Security Gateway |
| Versions | R81.20, R81.10 (EOS) |
| OS | Gaia |

## Symptoms

- * During ClusterXL failover, all Bidirectional Forwarding Detection (BFD) sessions for IPv6 BGP peerings drop. IPv4 peerings remain unaffected.

* BGP sessions for IPv6 stay active, but BFD behaves as if disabled.

* Packet capture with `tcpdump` shows BFD packets sent from the router, but the Security Gateway does not respond.

* Reconfiguring BFD sends packets, but the session does not establish.

* Completely reconfiguring BFD and BGP for a peer temporarily resolves the issue, but it recurs after failover.

## Cause

ClusterXL synchronization prevents proper propagation of the **BFD-Single_hop** service settings for IPv6 peerings. The service is not synchronized across cluster members during failover, so the Security Gateway ignores BFD packets for IPv6.

## Solution

This solution requires authentication. Please log in to view the full solution.

---

# Agent Instructions

This content is from the Check Point Support Center (https://support.checkpoint.com), the official knowledge base for Check Point cybersecurity products.

## Navigating This Knowledge Base

- **Complete index**: [llms.txt](https://support.checkpoint.com/llms.txt)
- **All SK articles**: [SecureKnowledge Sitemap](https://support.checkpoint.com/sitemaps/secureknowledge-sitemap-index.xml)
- **SK article URL pattern**: `https://support.checkpoint.com/results/sk/{skId}`
- **Markdown responses**: AI bot User-Agents automatically receive `text/markdown` content