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

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

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

`client.socket.cwnd` is a Read/Write
alias of `client.socket.tcpi_snd_cwnd`.

The size, in packets, of the current congestion window (CWND) for sending data
to the client. The TCP stack will not send more than this much data without it
being acknowledged by the client.