---
title: Connection reuse
description: How Smart Shield reduces origin connections by packaging multiple requests into one.
image: https://developers.cloudflare.com/core-services-preview.png
---

> Documentation Index  
> Fetch the complete documentation index at: https://developers.cloudflare.com/smart-shield/llms.txt  
> Use this file to discover all available pages before exploring further.

[Skip to content](#%5Ftop) 

### Tags

[ TCP ](https://developers.cloudflare.com/search/?tags=TCP)[ TLS ](https://developers.cloudflare.com/search/?tags=TLS) 

# Connection reuse

Smart Shield reduces the number of connections between Cloudflare and your origin server by batching multiple requests through shared connections. When requests from an [upper-tier data center](https://developers.cloudflare.com/smart-shield/configuration/smart-tiered-cache/) — the layer of Cloudflare's cache that sits closest to your origin — need to reach your server, Smart Shield sends them over a single connection instead of opening a new connection for each request. This reduces overall connections to your origin by 30% on average, which lowers resource consumption on your origin and reduces the risk of connection exhaustion under high traffic.

For more information, refer to the [Smart Shield announcement blog post ↗](https://blog.cloudflare.com/introducing-observatory-and-smart-shield/#protecting-and-accelerating-origins-with-smart-connection-reuse).

## About connection reuse

Every HTTP request requires a TCP connection between a client and a server. Each connection is identified by a pair of network addresses: the source IP address and port, and the destination IP address and port. Opening a new TCP connection has overhead — it requires a handshake between client and server, and a TLS negotiation if the connection is encrypted.

Connection reuse (also called persistent connections or keep-alive) avoids this overhead by sending multiple HTTP requests over a single TCP connection instead of opening a new connection for each request. HTTP/1.1 made this the default behavior.

For example, when a browser opens a connection to `shop.example.com`, the page may reference dozens of additional resources — stylesheets, images, scripts, and other files. Without connection reuse, each resource would require its own TCP connection. With connection reuse, all of these requests flow through the same connection.

### Connection coalescing (HTTP/2)

With HTTP/2, connection reuse extends further through connection coalescing. This allows requests for different hostnames to share a single connection, as long as two conditions are met:

* The hostnames resolve to the same destination IP address and port.
* The TLS certificate on the server covers both hostnames (for example, a certificate that lists both `shop.example.com` and `blog.example.com` in its Subject Alternative Names).

This means a connection originally opened for `shop.example.com` can also carry requests for `blog.example.com`, reducing the total number of connections to your origin even further.

## Connection reuse and Dedicated CDN Egress IPs

Connection reuse and connection coalescing are also considered when allocating your [Dedicated CDN Egress IPs](https://developers.cloudflare.com/smart-shield/configuration/dedicated-egress-ips/).

```json
{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/smart-shield/","name":"Smart Shield"}},{"@type":"ListItem","position":3,"item":{"@id":"/smart-shield/concepts/","name":"Concepts"}},{"@type":"ListItem","position":4,"item":{"@id":"/smart-shield/concepts/connection-reuse/","name":"Connection reuse"}}]}
```