---
title: "APIPA on W5500"
url: "https://maker.wiznet.io/forum/15168"
markdown_url: "https://maker.wiznet.io/forum/15168/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "kavaler"
created: "2024-02-29T01:30:19+09:00"
last_activity: "2024-03-01T23:45:48+09:00"
language: "en"
views: 156
replies: 2
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# APIPA on W5500

## Question

Asked by kavaler on 2024-02-29 in Ethernet Chips.

I want to implement APIPA using the W5500. Does the W5500 support ARP probe packets and ARP replies back to the user? If so, is the ARP probe/reply handling performed on the W5500 or does the user have to implement it?

## Replies

### Reply 1 by Eugeny, 2024-03-01

Must be a built-in functionality. If W5500 would not perform ARP requests before connecting or responding to ARP requests before remotes connect to it - then it would not function at all.

### Reply 2 by kavaler, 2024-03-01 (in reply to reply 1)

If implemented in the W5500 then it would be part of the IP address assignment protocol or a “detect duplicate IP address” protocol. In that case, the W5500 would do a ARP probe/ARP announcement to validate the assigned IP address. As far as I know, the address assignment is done by the user (i.e. static IP/DHCP) not by the W5500, so my question is whether the W5500 supports ARP probe/ARP announcement at all, and if so, in accordance with APIPA requirements. I know that the W5500 has mode where you can specify that ARP is required for each packet or cached, but that is different than ARP probe.

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Source: https://maker.wiznet.io/forum/15168