lwIP 2.2.1 Lightweight IP stack

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Applications » MDNS

## Macros
#define | MDNS_MAX_SERVICES 1
#define | MDNS_PROBE_DELAY_MS 250
#define | MDNS_MAX_STORED_PKTS 4
#define | MDNS_OUTPUT_PACKET_SIZE ((MDNS_MAX_SERVICES == 1) ? 512 : 1450)
#define | MDNS_RESP_USENETIF_EXTCALLBACK LWIP_NETIF_EXT_STATUS_CALLBACK
#define | LWIP_MDNS_SEARCH 1
#define | MDNS_MAX_REQUESTS 2
#define | MDNS_DEBUG LWIP_DBG_OFF

## Detailed Description

## Macro Definition Documentation

## ◆ LWIP_MDNS_SEARCH

#define LWIP_MDNS_SEARCH 1

LWIP_MDNS_SEARCH==1: Turn on search over multicast DNS module.

## ◆ MDNS_DEBUG

#define MDNS_DEBUG LWIP_DBG_OFF

MDNS_DEBUG: Enable debugging for multicast DNS.

## ◆ MDNS_MAX_REQUESTS

#define MDNS_MAX_REQUESTS 2

The maximum number of running requests

## ◆ MDNS_MAX_SERVICES

#define MDNS_MAX_SERVICES 1

LWIP_MDNS_RESPONDER==1: Turn on multicast DNS module. UDP must be available for MDNS transport. IGMP is needed for IPv4 multicast. The maximum number of services per netif

## ◆ MDNS_MAX_STORED_PKTS

#define MDNS_MAX_STORED_PKTS 4

The maximum number of received packets stored in chained list of known answers for pending truncated questions. This value define the size of the MDNS_PKTS mempool. Up to MDNS_MAX_STORED_PKTS pbuf can be stored in addition to TC questions that are pending.

## ◆ MDNS_OUTPUT_PACKET_SIZE

#define MDNS_OUTPUT_PACKET_SIZE ((MDNS_MAX_SERVICES == 1) ? 512 : 1450)

Payload size allocated for each outgoing UDP packet. Will be allocated with PBUF_RAM and freed after packet was sent. According to RFC 6762, there is no reason to retain the 512 bytes restriction for link-local multicast packet. 512 bytes isn't enough when 2 services need to be probed.

## ◆ MDNS_PROBE_DELAY_MS

#define MDNS_PROBE_DELAY_MS 250

The minimum delay between probes in ms. RFC 6762 require 250ms. In noisy WiFi environment, adding 30-50ms to this value help a lot for a successful Apple BCT tests.

## ◆ MDNS_RESP_USENETIF_EXTCALLBACK

#define MDNS_RESP_USENETIF_EXTCALLBACK LWIP_NETIF_EXT_STATUS_CALLBACK

MDNS_RESP_USENETIF_EXTCALLBACK==1: register an ext_callback on the netif to automatically restart probing/announcing on status or address change.