# Choosing a connection type
Source: https://www.stedi.com/docs/edi-platform/configure/trading-partners/connections/choosing-the-right-connection-type

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## title: Choosing a connection type

Often, your trading partner will request that you set up a specific type of connection protocol. However, it's important to understand the pros and cons of each approach.

## Connection recommendations

We recommend the following in order of most preferred to least preferred:

1. **[Stedi-run SFTP/FTPS](/edi-platform/configure/trading-partners/connections/stedi-ftp):** This connection type is extremely simple to set up and requires no ongoing maintenance. Outbound files sent to partners using Stedi SFTP are instantly available for partners to pick up. Inbound file processing is event-driven, and Stedi processes files instantly upon receipt. Stedi SFTP scales virtually infinitely. However, most large trading partners are unwilling to connect to external SFTP servers and require that you connect to their server instead.
2. **[Remote SFTP/FTPS](/edi-platform/configure/trading-partners/connections/remote-ftp):** Stedi can also connect to partner or third-party SFTP/FTPS/FTP servers. Stedi delivers outbound files to your trading partners instantly and processes inbound files on a polling schedule. By default, Stedi polls every 5 minutes, but you can set a custom polling interval in the connection's configuration settings.
3. **[AS2](/edi-platform/configure/trading-partners/connections/as2/as2-overview):** For partners that are unable to connect over SFTP, Stedi offers a hosted AS2 option. The AS2 protocol comes with serious drawbacks, so we recommend only using it as a last resort. **If your partner requests AS2 connectivity, we strongly recommend asking if SFTP is an option instead.**

## Problems with AS2

AS2 has several significant drawbacks:

* It is tedious to set up and requires getting complex, unfamiliar configuration settings just right. Debugging AS2 connection issues often involves getting both parties on a call to dive into detailed logs to figure out what is preventing the complex series of handshakes from completing successfully.

* It requires generating, distributing, and regularly updating certificates on an ongoing basis. This process can be labor-intensive and requires meticulous management and coordination with trading partners. Any lapse in the process leads to transaction processing downtime.

* Once set up, AS2 servers are typically inefficient at processing large files and high transaction volume.

### Why trading partners still want AS2

Regardless of its drawbacks, trading partners – particularly in the retail space – often push for AS2 as a preferred connection type. There are several reasons for this preference.

* **Historical:** When AS2 was first developed, it was positioned as way to move from closed, proprietary VANs (Value-Added Networks) to internet-based EDI. AS2 provided a way for retailers and suppliers to circumvent VANs and connect directly. Many retailers today still associate AS2 with "direct connectivity," despite the fact that SFTP provides a functionally identical but more modern mechanism.

* **Real-time communication:** There's a perception amongst retailers that AS2 connections are faster than SFTP. When an AS2 message is sent from one a retailer to its supplier, the supplier's AS2 server receives the message in real-time. In contrast, when a retailer places a file on its SFTP server, it's up to the supplier to pick up the file at their own discretion. Many legacy EDI platforms are unable to poll faster than 30 minute intervals, which slows down the flow of transactions. By default, Stedi polls for files at 5-minute intervals, and can poll as often as once per minute (though we don't recommend a one-minute interval because retailer SFTP servers are often quite slow and the poller can't finish processing the first polling request by the time the second request is initiated).

### Why we recommend SFTP instead

Modern data transmission technologies have now made many AS2 features obsolete. For the following reasons, we strongly recommend using SFTP instead of AS2 when possible.

* **Security:** SFTP, built on SSH (Secure Shell), provides robust encryption and secure data transfer capabilities. This makes the encryption aspect of AS2 less unique, as SFTP offers similar security features.

* **Authentication:** SFTP supports strong authentication mechanisms and ensures data integrity during transfer. This diminishes the advantages of AS2 digital signature and MDN features.

* **Ease of use and maintenance:** SFTP is generally considered easier to implement and maintain - there are no certificates to update or MDNs to manage.

* **Network compatibility:** SFTP is widely compatible with various network configurations and firewalls, making it more adaptable across different IT environments than AS2.

* **Performance and scalability:** SFTP tends to be more performant and scalable, especially for larger files or higher volumes of data transfer.