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

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

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

The number of bytes advertised in the maximum segment size
(MSS) option to the client during connection establishment and
therefore the maximum packet size that will be received from the
client. It is based on the TCP stack's cached information about the
path being used to connect to the client and which sizes have been
successfully used on the path in the past.