MTU & IPsec Overhead Calculator

Calculate exact TCP MSS values, IPsec ESP/GRE overhead, and inner payload limits to prevent tunnel fragmentation.

1. Physical & Tunnel Parameters

Physical Interface MTU (Bytes)

Tunnel Protocol

Transport Layer

Total Overhead

Max Tunnel MTU

Optimal TCP MSS

Recommended CLI Clamping Commands

# Cisco IOS MSS Clamping Command
interface Tunnel0
 ip tcp adjust-mss 1360