[devsite] add clarifications to multicast addressing primer (#5160)
diff --git a/doc/site/en/guides/thread-primer/ipv6-addressing.md b/doc/site/en/guides/thread-primer/ipv6-addressing.md
index 329f19d..3f38d73 100644
--- a/doc/site/en/guides/thread-primer/ipv6-addressing.md
+++ b/doc/site/en/guides/thread-primer/ipv6-addressing.md
@@ -226,10 +226,12 @@
the `ff03::2` multicast address. MTDs do not.
You might notice that Sleepy End Devices (SEDs) are not included as a
-recipient in the multicast table above. There is an additional unicast
-prefix-based multicast address used for All Thread Nodes, including SEDs. This
-multicast address varies by Thread network, because it is built on the
-unicast Mesh-Local prefix.
+recipient in the multicast table above. Instead, Thread defines
+link-local and realm-local scope unicast prefix-based IPv6 multicast
+address used for All Thread Nodes, including SEDs. These multicast
+addresses vary by Thread network, because it is built on the unicast
+Mesh-Local prefix (see [RFC 3306](https://tools.ietf.org/html/rfc3306)
+for more details on unicast-prefix-based IPv6 multicast addresses).
Arbitrary scopes beyond those already listed are also supported for Thread
devices.
diff --git a/doc/site/en/guides/thread-primer/node-roles-and-types.md b/doc/site/en/guides/thread-primer/node-roles-and-types.md
index 888b4c7..2db6213 100644
--- a/doc/site/en/guides/thread-primer/node-roles-and-types.md
+++ b/doc/site/en/guides/thread-primer/node-roles-and-types.md
@@ -50,8 +50,9 @@
### Minimal Thread Device
-A Minimal Thread Device does not subscribe to multicast traffic and forwards all
-messages to its Parent. There are two types of MTDs:
+A Minimal Thread Device does not subscribe to the all-routers
+multicast address and forwards all messages to its Parent. There are
+two types of MTDs:
* Minimal End Device (MED) — transceiver always on, does not need to poll for
messages from its parent
