From 2ad2018ab0cdea37ef8c83f6047e97775c2b03af Mon Sep 17 00:00:00 2001 From: Jonathan Hui Date: Fri, 12 Jun 2026 12:13:39 -0700 Subject: [PATCH] [primer] rename Router/REED to Mesh Extender/Extender-Capable Device Update the Thread Primer documentation to transition terminology from Router and Router Eligible End Device (REED) to Mesh Extender and Extender-Capable Device (ECD), respectively. - Rename "Router" to "Mesh Extender" (or "Active Mesh Extender" where referring specifically to the active parent role). - Rename REED (Router Eligible End Device) to Extender-Capable Device (ECD). - Rename "Router-Router links" to "Mesh Extender links". - Adjust roles, device types, addressing, and MLE attach descriptions to use the new terminology. - Fix grammatical errors and typos introduced during the transition. --- .../guides/thread-primer/ipv6-addressing.md | 43 ++--- .../guides/thread-primer/network-discovery.md | 86 +++++----- .../thread-primer/node-roles-and-types.md | 115 ++++++------- .../guides/thread-primer/router-selection.md | 151 +++++++++--------- 4 files changed, 202 insertions(+), 193 deletions(-) diff --git a/site/en/guides/thread-primer/ipv6-addressing.md b/site/en/guides/thread-primer/ipv6-addressing.md index 4025f101..9ecbfe7d 100644 --- a/site/en/guides/thread-primer/ipv6-addressing.md +++ b/site/en/guides/thread-primer/ipv6-addressing.md @@ -34,20 +34,22 @@ location in the network topology. ### How a Routing Locator is generated -All devices are assigned a Router ID and a Child ID. Each Router maintains a -table of all their Children, the combination of which uniquely identifies a -device within the topology. For example, consider the highlighted nodes in the -following topology, where the number in a Router (pentagon) is the Router ID, -and the number in an End Device (circle) is the Child ID: +All devices are assigned a Router ID and a Child ID. Each Parent +maintains a table of all its Children, the combination of which +uniquely identifies a device within the topology. For example, +consider the highlighted nodes in the following topology, where the +number in a Mesh Extender (pentagon) is the Router ID, and the number +in an End Device (circle) is the Child ID:
OT RLOC Topology
-Each Child's Router ID corresponds to their Parent (Router). Because a Router is -not a Child, the Child ID for a Router is always 0. Together, these values are -unique for each device in the Thread network, and are used to create the RLOC16, -which represents the last 16 bits of the RLOC. +Each Child's Router ID corresponds to its Parent (Mesh +Extender). Because a Mesh Extender is not a Child, the Child ID for a +Mesh Extender is always 0. Together, these values are unique for each +device in the Thread network, and are used to create the RLOC16, which +represents the last 16 bits of the RLOC. For example, here's how the RLOC16 is calculated for the upper-left node (Router ID = 1 and Child ID = 1): @@ -81,9 +83,10 @@ This same logic can be used to determine the RLOC for all highlighted nodes in t However, because the RLOC is based on the location of the node in the topology, the RLOC of a node can change as the topology changes. -For example, perhaps node `0x400` is removed from the Thread network. Nodes -`0x401` and `0x402` establish new links to different Routers, and as a result -they are each assigned a new RLOC16 and RLOC: +For example, perhaps node `0x400` is removed from the Thread +network. Nodes `0x401` and `0x402` establish new links to different +Mesh Extenders, and as a result they are each assigned a new RLOC16 +and RLOC:
OT Topology after Change @@ -272,7 +275,7 @@ What you've learned: * A Thread device has multiple unicast IPv6 addresses * An RLOC represents a device's location in the Thread network * An ML-EID is unique to a Thread device within a partition and should be used by applications -* Thread uses multicast to forward data to groups of nodes and routers +* Thread uses multicast to forward data to groups of nodes * Thread uses anycast when the RLOC of a destination is unknown To learn more about Thread's IPv6 addressing, see sections 5.2 and 5.3 of the @@ -319,12 +322,12 @@ To learn more about Thread's IPv6 addressing, see sections 5.2 and 5.3 of the
Incorrect.
-
The device is a REED.
+
The device is an Extender-Capable Device.
Close, but incorrect.
-
The device is a Router.
-
Correct. A Router always has a Child ID of 0.
+
The device is a Mesh Extender.
+
Correct. A Mesh Extender always has a Child ID of 0.
@@ -339,10 +342,10 @@ To learn more about Thread's IPv6 addressing, see sections 5.2 and 5.3 of the network.
-
A router dropped off the network.
-
Correct. When a router drops off a network, the network +
A Mesh Extender dropped off the network.
+
Correct. When a Mesh Extender drops off a network, the network topology changes, which may result in the device promoting itself to a - router and obtaining a new RLOC.
+ Mesh Extender and obtaining a new RLOC.
The camera entered sleep mode, which changed the network topology. @@ -381,7 +384,7 @@ To learn more about Thread's IPv6 addressing, see sections 5.2 and 5.3 of the
What type of addressing and routing does Thread use to forward data to - groups of nodes and routers?
+ groups of nodes?
unicast
Incorrect.
diff --git a/site/en/guides/thread-primer/network-discovery.md b/site/en/guides/thread-primer/network-discovery.md index 17457801..a622a59a 100644 --- a/site/en/guides/thread-primer/network-discovery.md +++ b/site/en/guides/thread-primer/network-discovery.md @@ -24,9 +24,8 @@ When creating a new Thread network, or searching for an existing one to join, a Thread device performs an active scan for 802.15.4 networks within radio range: 1. The device broadcasts an 802.15.4 Beacon Request on a specific Channel. -1. In return, any Routers or Router Eligible End Devices (REEDs) in range - broadcast a Beacon that contains their Thread network PAN ID, XPAN ID, and - Network Name. +1. In return, any Extender-Capable Devices (ECDs) in range broadcast a Beacon that contains + their Thread network PAN ID, XPAN ID, and Network Name. 1. The device repeats the previous two steps for each Channel. Once a Thread device has discovered all networks in range, it can either attach @@ -62,11 +61,12 @@ device has already been commissioned. ## Create a new network -If the device elects to create a new network, it selects the least busy Channel -and a PAN ID not in use by other networks, then becomes a Router and elects -itself the Leader. This device sends MLE Advertisement messages to other -802.15.4 devices to inform them of its link state, and responds to Beacon -Requests by other Thread devices performing an active scan. +If the device elects to create a new network, it selects the least +busy Channel and a PAN ID not in use by other networks, then becomes a +Mesh Extender and elects itself the Leader. This device sends MLE +Advertisement messages to other 802.15.4 devices to inform them of its +link state, and responds to Beacon Requests by other Thread devices +performing an active scan. ## Join an existing network @@ -75,13 +75,13 @@ ID, XPAN ID, and Network Name to match that of the target network via Thread Commissioning, then goes through the MLE Attach process to attach as a Child (End Device). This process is used for Child-Parent links. -Key Point: Every device, router-capable or not, initially attaches to a Thread +Key Point: Every device, ECD or not, initially attaches to a Thread network as a Child (End Device). 1. The Child sends a multicast [Parent Request](#1_parent_request) to all - neighboring Routers and REEDs in the target network. -1. All neighboring Routers and REEDs (if the Parent Request Scan Mask includes - REEDs) send [Parent Responses](#2_parent_response) with information about + neighboring Extender-Capable Devices in the target network. +1. All neighboring Mesh Extenders (and standby ECDs, if the Parent Request Scan Mask includes + standby ECDs) send [Parent Responses](#2_parent_response) with information about themselves. 1. The Child chooses a Parent device and sends a [Child ID Request](#3_child_id_request) to it. @@ -91,8 +91,7 @@ network as a Child (End Device). ### 1. Parent Request A Parent Request is a multicast request from the attaching device that is used -to discover neighboring Routers and Router Eligible End Devices (REEDs) in the -target network. +to discover neighboring Extender-Capable Devices in the target network.
OT MLE Attach Parent Request @@ -113,15 +112,16 @@ target network. Scan Mask - Limits the request to only Routers or to both Routers and REEDs + Limits the request to only Mesh Extenders or to all Extender-Capable Devices ### 2. Parent Response -A Parent Response is a unicast response to a Parent Request that provides -information about a Router or REED to the attaching device. +A Parent Response is a unicast response to a Parent Request that +provides information about an Extender-Capable Device to the attaching +device.
OT MLE Attach Parent Response @@ -143,31 +143,31 @@ information about a Router or REED to the attaching device. Link Frame Counter - 802.15.4 Frame Counter on the Router/REED + 802.15.4 Frame Counter on the Extender-Capable Device MLE Frame Counter - MLE Frame Counter on the Router/REED + MLE Frame Counter on the Extender-Capable Device Source Address - RLOC16 of the Router/REED + RLOC16 of the Extender-Capable Device Link Margin - Receive signal quality of the Router/REED + Receive signal quality of the Extender-Capable Device Connectivity - Describes the Router/REED’s level of connectivity + Describes the Extender-Capable Device's level of connectivity Leader Data - Information about the Router/REED’s Leader + Information about the Extender-Capable Device's Leader Challenge @@ -179,11 +179,11 @@ information about a Router or REED to the attaching device. ### 3. Child ID Request -A Child ID Request is a unicast request from the attaching device (Child) that -is sent to the Router or REED (Parent) for the purpose of establishing a -Child-Parent link. If the request is sent to a REED, it [upgrades itself to a -Router](router-selection.md) before -accepting the request. +A Child ID Request is a unicast request from the attaching device +(Child) that is sent to the Extender-Capable Device (Parent) for the +purpose of establishing a Child-Parent link. If the request is sent to +a standby Extender-Capable Device, it [upgrades itself to a Mesh +Extender](router-selection.md) before accepting the request.
OT MLE Attach Child ID Request @@ -242,8 +242,7 @@ Child to confirm that a Child-Parent link has been established. Child ID Response Message Contents - Source - Address + Source Address Parent's RLOC16 @@ -251,20 +250,17 @@ Child to confirm that a Child-Parent link has been established. Child's RLOC16 - Leader - Data + Leader Data Information about the Parent’s Leader (RLOC, Partition ID, Partition weight) - Network - Data + Network Data Information about the Thread network (on-mesh prefixes, address autoconfiguration, more-specific routes) - Route - (REED only) + Route (standby ECDs only) Route propagation @@ -272,8 +268,7 @@ Child to confirm that a Child-Parent link has been established. Inactivity duration before the Parent removes the Child - Address - Registration (MEDs and SEDs only) + Address Registration (MEDs and SEDs only) Confirm registered addresses @@ -323,19 +318,18 @@ What you've learned:
What is a Parent Request used for?
-
To discover neighboring Routers and Router Eligible End Devices - (REEDs) in the target network.
+
To discover neighboring Extender-Capable Devices in the target network.
Correct. A Parent Request is issued by a device seeking to attach to a network.
-
To announce that a Router is becoming a parent.
-
Incorrect. A Router does not initiate a Parent-Child relationship - with another network device. Instead, a network device selects a Router - to become its Child.
+
To announce that an Extender-Capable Device is becoming a parent.
+
Incorrect. A Mesh Extender does not initiate a Parent-Child relationship + with another network device. Instead, a network device selects an Extender-Capable Device + to become its Parent.
-
To request that a Router Eligible End Device be promoted to a Router. +
To request that an Extender-Capable Device be promoted to a Mesh Extender.
Incorrect.
@@ -378,7 +372,7 @@ What you've learned:
Incorrect.
-
REED (Router-Eligible End Device)
+
Mesh Extender
Incorrect.
 diff --git a/site/en/guides/thread-primer/node-roles-and-types.md b/site/en/guides/thread-primer/node-roles-and-types.md index 94283b48..1d42ca5c 100644 --- a/site/en/guides/thread-primer/node-roles-and-types.md +++ b/site/en/guides/thread-primer/node-roles-and-types.md @@ -8,9 +8,9 @@ In a Thread network, nodes are split into two forwarding roles: -### Router +### Mesh Extender -A Router is a node that: +A Mesh Extender is a node that: * forwards packets for network devices * provides secure commissioning services for devices trying to join the network @@ -20,13 +20,14 @@ A Router is a node that: An End Device (ED) is a node that: -* communicates primarily with a single Router +* communicates primarily with a single Mesh Extender * does not forward packets for other network devices * can disable its transceiver to reduce power -Key Point: The relationship between Router and End Device is a Parent-Child -relationship. An End Device attaches to exactly one Router. The Router is always -the Parent, the End Device the Child. +Key Point: The relationship between a Mesh Extender and an End Device +is a Parent-Child relationship. An End Device attaches to exactly one +Mesh Extender. The Mesh Extender is always the Parent, the End Device +the Child. ## Device types @@ -40,13 +41,16 @@ Furthermore, nodes comprise a number of types. A Full Thread Device (FTD) always has its radio on, subscribes to the all-routers multicast address, and maintains IPv6 address mappings. There are -three types of FTDs: +two types of FTDs: -* Router -* Router Eligible End Device (REED) — can be promoted to a Router -* Full End Device (FED) — cannot be promoted to a Router +* Extender-Capable Device (ECD) +* Full End Device (FED) -An FTD can operate as a Router (Parent) or an End Device (Child). +An Extender-Capable Device can be in either the Mesh Extender or +standby ECD role. In the standby role, it's always an End Device +(Child). + +A FED is always an End Device (Child). ### Minimal Thread Device @@ -63,18 +67,19 @@ An MTD can only operate as an End Device (Child). ### Upgrading and downgrading -When a REED is the only node in reach of a new End Device wishing to join the -Thread network, it can upgrade itself and operate as a Router: +When a standby ECD is the only node in reach of a new Thread device +wishing to join the Thread network, it can upgrade itself and operate +as a Mesh Extender:
-OT End Device to Router +OT End Device to Mesh Extender
-Conversely, when a Router has no children, it can downgrade itself and operate -as an End Device: +Conversely, when a Mesh Extender has no children, it can downgrade +itself and operate as a standby ECD:
-OT Router to End Device +OT Mesh Extender to End Device
## Other roles and types @@ -85,9 +90,10 @@ as an End Device: OT Leader and Border Router
-The Thread Leader is a Router that is responsible for managing the set of -Routers in a Thread network. It is dynamically self-elected for fault tolerance, -and aggregates and distributes network-wide configuration information. +The Thread Leader is a Mesh Extender that is responsible for managing +the set of Mesh Extenders in a Thread network. It is dynamically +self-elected for fault tolerance, and aggregates and distributes +network-wide configuration information. Note: There is always a single Leader in each Thread network [partition](#partitions). @@ -132,22 +138,23 @@ There are limits to the number of device types a single Thread network supports. Role | Limit ----|---- Leader | 1 -Router | 32 -End Device | 511 per Router +Mesh Extender | 32 +End Device | 511 per Mesh Extender -Thread tries to keep the number of Routers between 16 and 23. If a REED attaches -as an End Device and the number of Routers in the network is below 16, it -automatically promotes itself to a Router. +Thread tries to keep the number of Mesh Extenders between 16 and +23. If an ECD attaches as an End Device and the number of Mesh +Extenders in the network is below 16, it automatically promotes itself +to a Mesh Extender. ## Recap What you learned: -* A Thread device is either a Router (Parent) or an End Device (Child) +* A Thread device is either a Mesh Extender (Parent) or an End Device (Child) * A Thread device is either a Full Thread Device (maintains IPv6 address mappings) or a Minimal Thread Device (forwards all messages to its Parent) -* A Router Eligible End Device can promote itself to a Router, and vice versa -* Every Thread network partition has a Leader to manage Routers +* A standby ECD can promote itself to a Mesh Extender, and vice versa +* Every Thread network partition has a Leader to manage Mesh Extenders * A Border Router is used to connect Thread and non-Thread networks * A Thread network might be composed of multiple partitions @@ -162,7 +169,7 @@ What you learned:
Incorrect.
-
Router.
+
Mesh Extender.
Correct.
@@ -201,46 +208,46 @@ What you learned:
-
Which of the following statements about Routers is not true?
+
Which of the following statements about Mesh Extenders is not true?
-
A Router can disable its transceiver to reduce power.
-
Devices that are functioning as Routers do not disable their - transceiver. (If they did, they'd be unable to function properly as a - Router.)
+
A Mesh Extender can disable its transceiver to reduce power.
+
Devices that are functioning as Mesh Extenders do not disable their + transceivers. (If they did, they'd be unable to function properly as a + Mesh Extender.)
-
A Router forwards packets for network devices.
+
A Mesh Extender forwards packets for network devices.
This statement is true.
-
A Router keeps its transceiver enabled at all times.
-
This statement is true. In order to function properly as a Router, +
A Mesh Extender keeps its transceiver enabled at all times.
+
This statement is true. In order to function properly as a Mesh Extender, a device must keep its transceiver online at all times.
-
A Router provides secure commissioning services for devices trying +
A Mesh Extender provides secure commissioning services for devices trying to join the network.
This statement is true. Commissioning is an important function of a - Thread Router.
+ Mesh Extender.
-
When can a device upgrade itself to a Router?
+
When can a device upgrade itself to a Mesh Extender?
-
When it is a REED and it is the only node in reach of a new End - Device seeking to join the Thread network.
-
That's right. Under these circumstances, a REED can promote itself - to a Router.
+
When it is a standby Extender-Capable Device and it is the only node in reach of a new Thread + device seeking to join the Thread network.
+
That's right. Under these circumstances, a standby Extender-Capable Device can promote itself + to a Mesh Extender.
When it is an End Device seeking to join the Thread network.
Incorrect.
-
When it is a REED and the Thread network has merged with a larger +
When it is a standby Extender-Capable Device and the Thread network has merged with a larger network.
Incorrect.
@@ -249,24 +256,24 @@ What you learned:
-
When can a Router cause itself to stop acting as a Router?
+
When can a Mesh Extender cause itself to stop acting as a Mesh Extender?
When it has no children.
-
That's correct. A Router with no children may revert to - an End Device on its own.
+
That's correct. A Mesh Extender with no children may revert to + a standby ECD on its own.
When a new End Device is seeking to join the Thread network.
-
Wrong. A Router cannot revert to an End Device in this scenario. +
Wrong. A Mesh Extender cannot revert to a standby ECD in this scenario.
-
When another device on the network elects to become a Router. +
When another device on the network elects to become a Mesh Extender.
-
This could be true. If the number of Thread routers increases to 24 - or more, existing Thread routers can start evaluating whether to become an - end device. +
This could be true. If the number of Mesh Extenders increases to 24 + or more, existing Mesh Extenders can start evaluating whether to become a + standby ECD.
@@ -292,7 +299,7 @@ What you learned:
Incorrect.
-
All the Routers in the network have gone offline.
+
All the Mesh Extenders in the network have gone offline.
Incorrect. In that case, none of the nodes would be able to communicate with one another.
diff --git a/site/en/guides/thread-primer/router-selection.md b/site/en/guides/thread-primer/router-selection.md index f1e71b2e..e36d9272 100644 --- a/site/en/guides/thread-primer/router-selection.md +++ b/site/en/guides/thread-primer/router-selection.md @@ -1,4 +1,4 @@ -# Router Selection +# Mesh Extender Selection ## Connected Dominating Set @@ -6,53 +6,57 @@ OT Connected Dominating Set
Example of a Connected Dominating Set
-Routers must form a Connected Dominating Set (CDS), which means: +Mesh Extenders must form a Connected Dominating Set (CDS), which means: -1. There is a Router-only path between any two Routers. -1. Any one Router in a Thread network can reach any other Router by staying - entirely within the set of Routers. -1. Every End Device in a Thread network is directly connected to a Router. +1. There is a Mesh Extender-only path between any two Mesh Extenders. +1. Any one Mesh Extender in a Thread network can reach any other Mesh Extender by staying + entirely within the set of Mesh Extenders. +1. Every End Device in a Thread network is directly connected to a Mesh Extender. A distributed algorithm maintains the CDS, which ensures a minimum level of redundancy. Every device initially attaches to the network as an End Device (Child). As the state of the Thread network changes, the algorithm adds or -removes Routers to maintain the CDS. +removes Mesh Extenders to maintain the CDS. -Thread adds Routers to: +Thread adds Mesh Extenders to: -* Increase coverage if the network is below the Router threshold of 16 +* Increase coverage if the network is below the Mesh Extender threshold of 16 * Increase path diversity * Maintain a minimum level of redundancy * Extend connectivity and support more Children -Thread removes Routers to: +Thread removes Mesh Extenders (switching them to standby +Extender-Capable Devices (ECDs)) to: -* Reduce the Routing state below the maximum of 32 Routers -* Allow new Routers in other parts of the network when needed +* Keep the Routing state below the maximum of 32 Mesh Extenders +* Allow new Mesh Extenders in other parts of the network when needed -## Upgrade to a Router +## Upgrade to a Mesh Extender -After attaching to a Thread network, the Child device may elect to become a -Router. Before initiating the MLE Link Request process, the Child sends an -Address Solicit message to the Leader, asking for a Router ID. If the Leader -accepts, it responds with a Router ID and the Child upgrades itself to a Router. +After attaching to a Thread network, a Child device that is an +Extender-Capable Device may elect to become a Mesh Extender. Before +initiating the MLE Link Request process, the Child sends an Address +Solicit message to the Leader, asking for a Router ID. If the Leader +accepts, it responds with a Router ID and the Child upgrades itself to +a Mesh Extender. The MLE Link Request process is then used to establish bi-directional -Router-Router links with neighboring Routers. +Mesh Extender links with neighboring Mesh Extenders. -1. The new Router sends a multicast [Link Request](#1_link_request) to - neighboring Routers. -1. Routers respond with [Link Accept and Request](#2_link_accept_and_request) +1. The new Mesh Extender sends a multicast [Link Request](#1_link_request) to + neighboring Mesh Extenders. +1. Mesh Extenders respond with [Link Accept and Request](#2_link_accept_and_request) messages. -1. The new Router responds to each Router with a unicast [Link - Accept](#3_link_accept) to establish the Router-Router link. +1. The new Mesh Extender responds to each Mesh Extender with a unicast [Link + Accept](#3_link_accept) to establish the Mesh Extender link. ### 1. Link Request -A Link Request is a request from the Router to all other Routers in the Thread -network. When first becoming a Router, the device sends a multicast Link Request -to `ff02::2`. Later, after discovering the other Routers via MLE Advertisements, -the devices send unicast Link Requests. +A Link Request is a request from the Mesh Extender to all other Mesh +Extenders in the Thread network. When first becoming a Mesh Extender, +the device sends a multicast Link Request to `ff02::2`. Later, after +discovering the other Mesh Extenders via MLE Advertisements, the +devices send unicast Link Requests.
OT MLE Link Request @@ -80,7 +84,7 @@ the devices send unicast Link Requests. Leader Data - Information about the Router's Leader, as stored on the sender (RLOC, + Information about the Mesh Extender's Leader, as stored on the sender (RLOC, Partition ID, Partition weight) @@ -98,9 +102,9 @@ reduce the number of messages from four to three. ### 3. Link Accept -A Link Accept is a unicast response to a Link Request from a neighboring Router -that provides information about itself and accepts the link to the neighboring -Router. +A Link Accept is a unicast response to a Link Request from a +neighboring Mesh Extender that provides information about itself and +accepts the link to the neighboring Mesh Extender.
OT MLE Link Accept @@ -138,42 +142,43 @@ Router. Leader Data - Information about the Router's Leader, as stored on the sender (RLOC, + Information about the Mesh Extender's Leader, as stored on the sender (RLOC, Partition ID, Partition weight) -## Downgrade to a REED +## Downgrade to a standby Extender-Capable Device -When a Router downgrades to a REED, its Router-Router links are disconnected, -and the device initiates the MLE Attach process to establish a Child-Parent -link. +When a Mesh Extender downgrades to a standby Extender-Capable Device, +its Mesh Extender links are disconnected, and the device initiates the +MLE Attach process to establish a Child-Parent link. -See [Join an existing -network](network-discovery.md) -for more information on the MLE Attach process. +See [Join an existing network](network-discovery.md) for more +information on the MLE Attach process. ## One-way receive links In some scenarios, it may be necessary to establish a one-way receive link. -After a Router reset, neighboring Routers may still have a valid receive link -with the reset Router. In this case, the reset Router sends a Link Request -message to re-establish the Router-Router link. +After a Mesh Extender reset, neighboring Mesh Extenders may still have +a valid receive link with the reset Mesh Extender. In this case, the +reset Mesh Extender sends a Link Request message to re-establish the +existing Mesh Extender link. -An End Device may also wish to establish a receive link with neighboring -non-Parent Routers to improve multicast reliability. We'll learn more about this -when we get to Multicast Routing. +An End Device may also wish to establish a receive link with +neighboring non-Parent Mesh Extenders to improve multicast +reliability. We'll learn more about this when we get to Multicast +Routing. ## Recap What you've learned: -* Routers in a Thread network must form a Connected Dominating Set (CDS) -* Thread devices are upgraded to Routers or downgraded to End Devices to - maintain the CDS -* The MLE Link Request process is used to establish Router-Router links +* Mesh Extenders in a Thread network must form a Connected Dominating Set (CDS) +* Extender-Capable Devices (ECDs) can be upgraded to Mesh Extenders or + downgraded to standby ECDs to maintain the CDS +* The MLE Link Request process is used to establish Mesh Extender links ## Check your understanding @@ -182,21 +187,21 @@ What you've learned:
Which of these rules are not enforced by a Connected Dominating Set (CDS)?
-
There is a Router-only path between any two Routers.
+
There is a Mesh Extender-only path between any two Mesh Extenders.
Incorrect.
-
Any one Router in a Thread network can reach any other Router by - staying entirely within the set of Routers.
+
Any one Mesh Extender in a Thread network can reach any other Mesh Extender by + staying entirely within the set of Mesh Extenders.
Incorrect.
Every End Device in a Thread network is directly connected to a - Router.
+ Mesh Extender.
Incorrect.
-
Only one Router in a Thread network may be a Border Router.
+
Only one Mesh Extender in a Thread network may be a Border Router.
Correct. A Thread network may have multiple Border Routers.
@@ -204,22 +209,22 @@ What you've learned:
-
Why might a Router be removed from a Thread network?
+
Why might a Mesh Extender be removed (i.e. downgraded to a standby Extender-Capable Device) from a Thread network?
-
To reduce the Routing state below the maximum of 32 Routers.
+
To keep the Routing state below the maximum of 32 Mesh Extenders.
Correct. Thread networks strive to maintain an optimal number of - Routers. The most Routers that any Thread network should have is 32. + Mesh Extenders. The most Mesh Extenders that any Thread network should have is 32.
To free up channels.
-
Incorrect. The number of routers has no relation to channel usage +
Incorrect. The number of Mesh Extenders has no relation to channel usage or capacity.
-
To allow the election of new Routers in other parts of the network +
To allow the election of new Mesh Extenders in other parts of the network when needed.
-
Correct. Reducing the number of active Routers in one part of a +
Correct. Reducing the number of Mesh Extenders in one part of a Thread network increases its ability to ramp up routing capacity elsewhere.
@@ -228,21 +233,21 @@ What you've learned:
-
What must happen before a REED that is attempting to become - a Router can establish direct links with the other Routers?
+
What must happen before an Extender-Capable Device that is attempting to become + a Mesh Extender can establish direct links with the other Mesh Extenders?
-
The REED must send an Address Solicit message to the network Leader. +
The Extender-Capable Device must send an Address Solicit message to the network Leader.
Correct.
-
The Leader must grant a Router ID to the REED.
-
Correct. Without a Router ID, the REED remains a Child device.
+
The Leader must grant a Router ID to the Extender-Capable Device.
+
Correct. Without a Router ID, the Extender-Capable Device remains an End Device (Child).
-
The REED must send an MLE Link Request.
+
The Extender-Capable Device must send an MLE Link Request.
Wrong. The MLE Link Request is how the device establishes links to - other Routers once it has become a Router.
+ other Mesh Extenders once it has become a Mesh Extender.
@@ -250,16 +255,16 @@ What you've learned:
Which of the following statements accurately describes what happens - when a Router downgrades?
+ when a Mesh Extender downgrades?
-
The device automatically remains on the network but as a Child (REED). +
The device automatically remains on the network but as a Child (standby Extender-Capable Device).
-
Wrong. There are more steps involved when a Router downgrades.
+
Wrong. There are more steps involved when a Mesh Extender downgrades.
The device must initiate the MLE Attach process to establish a new connection to the network.
-
Correct. A device that downgrades from Router to REED is +
Correct. A device that downgrades from a Mesh Extender to a standby Extender-Capable Device is disconnected and must renegotiate its connection to the network.
@@ -267,7 +272,7 @@ What you've learned:
-
What process is used to establish Router-Router links?
+
What process is used to establish Mesh Extender links?
The MLE Link Request process.
Correct.
@@ -275,7 +280,7 @@ What you've learned:
The Link Accept and Request process.
Incorrect. There's no such thing as a Link Accept and Request process. - Link Accept and Request messages are sent by Routers in + Link Accept and Request messages are sent by Mesh Extenders in response to Link Request messages as part of the MLE Link Request process.