# MLD

Multicast Listener Discovery（簡稱MLD）是從IGMPv2（Internet Group Management Protocol version 2）衍生而來，目的是讓IPv6 router有能力發現每個連接的link上的multicast listener（聆聽者），並且具體知道這些聆聽者感興趣的是哪些multicast位址， 同時在每個link上建立個別的multicast listener列表。只要multicast listener列表發生變化，router就會透過Multicast Routing Protocol與其它鄰近的routers交換這些訊息，以確保multicast封包能恰當地傳送或阻斷到multicast listeners連接的link（Multicast Routing Protocol不在本書的討論範圍內） MLD是ICMPv6的子協議， 也就是說，MLD是整個ICMPv6 message的子集合

MLD Packet Structure

**Reference:**

```
RFC 2710  Multicast Listener Discovery for IPv6
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://fashaun.gitbook.io/dev-protocol/ipv6/mld.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.