AIT Chapter 6 Internet of Things
Questions about the lecture 'Advanced Internet Technology' of the RWTH Aachen Chapter 6 Internet of Things
Questions about the lecture 'Advanced Internet Technology' of the RWTH Aachen Chapter 6 Internet of Things
Set of flashcards Details
| Flashcards | 48 |
|---|---|
| Language | English |
| Category | Computer Science |
| Level | University |
| Created / Updated | 05.02.2017 / 03.10.2018 |
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What are the complexity of the commercial world regarding the Internet of things (IoT)? [4]
1. Complex
2. Diversity of link layer technologies and application areas
3. Restrict to small multi-hop networks for robustness
4. Communicate with remote services via gateways
How to approach on connecting things (IoT)? [3]
1. Adapt Internet architecture IP
2. Gateways can locally represent sensor nodes if necessary
3. No single protocol stack but inter-operable network communication
What does 6LoWPAN stands for?
IPv6 over low power wireless personal area network
Which devices exist in a 6LoWPAN? [3]
1. Host 2. gateway (dual stack) and 3. sensor node
Which layers are similar for all 6LoWPAN devices? [3]
1. Application layer
2. Transport layer (TCP/UDP)
3. Network layer (IP)
What is the specification of the lowest layer for the host regarding 6LoWPAN devices?
Ethernet or other MAC/PHY
What is the specification of the lowest layer for the gateway (dual stack) regarding 6LoWPAN devices?
Ethernet or other MAC/PHY AND adaption layer 802.15.4 MAC/PHY
What is the specification of the lowest layer for the sensor node regarding 6LoWPAN devices?
Adaption layer 802.15.4 MAC/PHY
What is the purpose of the adaption layer for 6LoWPAN?
Integrates constrained nodes and networks into IPv6 world
Which topologies are supported by the adaption layer of 6LoWPAN? [3]
1. One edge router via backhaul link
2. Several edge routers via backbone link
3. Ad-hoc isolated network
What are the four setup steps of the adaption layer for 6LoWPAN? [4]
1. Commissioning
2. Bootstrapping
3. Route initialization
4. Maintain 1-3
What are the characteristics of commissioning for the setup of the adaption layer for 6LoWPAN? [2]
1. Link-layer connectivity to devices
2. Compatible to physical and link-layer settings
What are link-layer settings of commissioning for the setup of the adaption layer for 6LoWPAN? [4]
1. Channel, modulation, data-rate
2. Addressing mode (16 or 64-bit)
3. MAC mode (beaconless or superframe)
4. Security (on or off, key)
What are the characteristics of bootstrapping for the setup of the adaption layer for 6LoWPAN? [3]
1. Address configuration
2. Discovery of neighbors
3. Registrations
How do addresses on the adaption layer for 6LoWPAN look like? [2]
1. 64-bit IPv6 prefix per subnet (P)
2. 64/16-bit interface ID (IID)
What are the three steps of auto configuring addresses due to neighborhood on the adaption layer for 6LoWPAN? [3]
1. Router discovery
2. Address generation based on prefix
3. Neighbor solicitation
How does router discovery works on the adaption layer for 6LoWPAN? [2]
1. Locate with router solicitation
2. Wait for periodic router advertisement with prefix
How does neighbor solicitation works on the adaption layer for 6LoWPAN? [2]
1. Duplicate address detection (DAD)
2. Resolve MAC addresses for known IP addresses
What is the purpose of header compression on the adaption layer for 6LoWPAN?
Increase application level throughput (So-called goodput)
Which properties are considered regarding header compression on the adaption layer for 6LoWPAN? [3]
1. Redundant header information (version, payload length)
2. Dynamic header content (Next header, traffic class, flow label)
3. IPv6 addresses (P,IID)
What can be ameliorated for IPv6 addresses regarding header compression on the adaption layer for 6LoWPAN? [2]
1. Link-local prefix, well-known “contexts”
2. Link-local communication, source and destination
Give an example header compression on the adaption layer for 6LoWPAN?
40byte IPv6 + 8byte UDP → 6byte // Best case
What is the motivation for packet fragmentation on the adaption layer for 6LoWPAN? [2]
1. IPv6 max transmission units (MTUs) > 1280bytes
2. IEEE 802.15.4 payload of 80-100bytes
How does packet fragmentation on the adaption layer for 6LoWPAN works? [2]
1. Every fragment contains MAC addresses, size and tag information and payload offset
2. Only first fragment contains routing information
How does forwarding in packet fragmentation on the adaption layer for 6LoWPAN works? [4]
1. For IPv6 each fragment needs IP header
2. After split first fragment needed for routing decision
3. Thus, reassembly packet at each hop
4. Less transmission OH
What does ROLL stand for regarding IoT?
Routing over low-power and lossy networks (LLNs)
What does RPL stand for regarding IoT?
Routing protocol for LLNs
What are the challenges for ROLL? [3]
1. LLNs consist of up to thousands constrained nodes
2. Unstable links with low data rates and low packet delivery rates
3. Traffic not simply point-to-point but point-to-multipoint
What is the definition of a directed acyclic graph (DAG) in ROLL?
Directed graph without cycles
What is the definition of a destination oriented DAG (DODAG) in ROLL?
DAG rooted towards a single destination
What is an alternative description for DODAGs in ROLL?
RPL instance
What are the characteristics of an RPL instance in ROLL? [3]
1. Defines one optimization objective
2. Based on metrics with link (Reliability, latency) and node properties (Powered)
3. Run multiple concurrently for different optimization criteria
What are the characteristics for the rank in RPL instance in ROLL? [3]
1. Relative position in DODAG
2. Strictly increasing from root
3. Avoid and detect loops
How does a construction of an RPL instance looks like? [5]
1. Send periodically link-local multicast DIO messages
2. Typically send by DODAG root
3. Receiver uses DIO to join new DODAG or maintain existing one
4. Send DIS message to solicit a DIO
5. Choose (only) parents minimizing path cost to the root
What are the flows in LLNs? [2]
1. Many-to-one (Sensors → sink/gateway)
2. One-to-many (Gateway → sensors/actuators)
What are the different control messages in ROLL? [3]
1. DAG information object (DIO)
2. DAG information solicitation (DIS)
3. Destination advertisement object (DAO)
What are the characteristics of the DAG information object (DIO)? [3]
1. To discover RPL instance
2. Learn its configuration
3. Select DODAG parents
What is the characteristic of the DAG information solicitation (DIS)? [1]
Solicit DODAG information object from RPL node
What is the characteristic of the Destination advertisement object (DAO)? [1]
Propagate destination information upwards in DODAG
What does CoRE stand for in IoT?
Constrained representational state transfer (RESTful) environments (2004)
