# Redundancy and Interface Distribution of Tunnel-Service Interfaces Overview

The redundancy and distribution mechanisms supported for tunnel-service ports configured on ISMs differ from those supported for SMs, the ES2-S1 Service IOA, and shared tunnel-server ports.

The following topics describe the redundancy and interface distribution mechanisms for all tunnel-server ports:

- SMs, ES2-S1 Service IOA, and Shared Tunnel-Server Modules Overview
- ISMs Overview

#### Related Documentation

- Tunnel-Service and IPSec-Service Overview
- Tunnel-Service Interface Platform Considerations
- SMs, ES2-S1 Service IOA, and Shared Tunnel-Server Modules Overview
- ISMs Overview