---
title: client.socket.tcpi_pmtu
summary: null
url: >-
  https://www.fastly.com/documentation/reference/vcl/variables/client-connection/client-socket-tcpi-pmtu
---

**Type:** INTEGER  
**Access:** read-only

**Available in:** recv, deliver, log, error

The number of bytes the TCP stack believes can be transmitted in one
IP packet without fragmentation to the client. This value is derived
on a per-path basis and may be cached between different connections
that share the same path.