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103 Cards in this Set
- Front
- Back
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Why is Mobile IP needed? |
Some users have a need to move while they are working |
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What are some challenges of Mobility? |
Maintaining continuous and transparent IP connectivity while crossing network boundaries, e.g. subnets or between networks How the IP network will transparently handle user’s mobility ? |
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What is a Mobile Node (MN)? |
A network host that can change its point of attachment from one link to another
MN is always reachable and identified by its home address |
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What is a Home Address (HoA)? |
An IP address assigned to the mobile node within its home link |
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What is a Handover? |
A change in a MN’s point of attachment Change of IP address |
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What is a Home Link? |
Is the link on which a MN’s Home Address is defined The link to which all mobile packet are delivered when MN it is at home |
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What is a Home Agent (HA)? |
It is a router on a MN’s home link It is responsible for forwarding data addressed to the MN’s HoA |
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What is a Foreign Agent (FA)? |
It is a router located on the visited network It provides routing services to the mobile node while registered |
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What is a Care-of Address (CoA)? |
An IP address associated with a mobile node while visiting a foreign link In the foreign link, the mobile node can get multiple care-of addresses |
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What is Mobility Binding? |
The association of the HoA of an MN with its current CoA |
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What is a Correspondent Node? |
A peer with which a mobile node is communicating It may be mobile or stationary node |
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What is Micro-Mobility? |
It is a mobility inside the same IP domain The MN roams always inside its home network |
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What is a Macro-Mobility? |
It a mobility across different IP domains The MN moves from one domain to another |
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Explain the process of an MN moving to a foreign network with Mobile IPv4 |
MN moves from home network to foreign network (handover) MN registers it HoA and CoA with its HA CN sends data to the MN's HA, the HA forwards the data to the MN's CoA |
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List some requirements for Mobile IPv4 |
An MN should be able to continue communicating with other nodes after handover An MN can change its point of attachment (link-layer) without changing its IP address An MN should be able to communicate with mobile node and non compatible mobile nodes (stationary and mobile nodes) When an MN moves to a new network, it updates its location with its HA using authenticated messages |
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Explain the principle of Mobile IPv4 Agent Discovery |
It is an extension of the ICMP Router Discovery (RFC 1256 ) Both HAs and FAs advertise their availability on each link they serve An MN can send a solicitation on the link to learn their presence An HA or an FA uses Agent Advertisement messages to advertise their availability on each link they serve The Agent Advertisement messages are broadcasted periodically An MN relies on these message to detect its movement from the home network to a visited network An MN can obtain its CoA from the Agent Advertisement messages An MN can request Agent Advertisement messages from the HA or the MN by sending Agent Solicitation messages |
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Explain Mobile IPv4 Registration |
When an MN moves to a new network and gets a new CoA it registers the CoA with its HA
The registration is needed to avoid application interruption after handover The MN sends a Registration Request message that contains both its HoA and its CoA The HA authenticate the Registration Request message and responds with a Registration Reply message The Registration is valid for a given lifetime (CoA’s lifetime) |
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Describe the two way data is forwarded with Mobile IPv4 |
Data Forwarding (1) The CN sends data to the MN's HA (IPsrc = CN, IPdst = HoA) HA encapsulates the data and forms tunnel to the FA (IPsrc = HA, IPdst = FA) then sends the data The FA forwards the data to the MN Data Forwarding (2) The CN sends data to the MN's HA (IPsrc = CN, IPdst = HoA) HA encapsulates the data and forms tunnel to the MN (IPsrc = HA, IPdst = CoA) then sends the data |
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Explain Mobile IPv4 Route Optimisation |
Data sent from CN to MN's HA HA sends Binding Update (BU) to CN with the MN's current CoA Data sent directly to MN's CoA from the CN |
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What are the two methods of Mobile IPv4 Deregistration? |
Implicit Deregistration The Binding expires without an updating from the MN When an MN comes back home, Explicit Deregistration An MN can explicitly send a Deregistration Request message to its HA The HA authenticates and validates this request by sending a Deregistration Reply message A Deregistration message is similar to the registration message expect that the lifetime is null |
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What is the purpose of Hierarchical Mobile IPv4? |
Eliminates Triangle Routing within the same domain (micro-mobility) Hides the MN’s mobility from the CN and the HA Helps Fast Handover |
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What is Triangle Routing? |
Triangle routing is caused because the CN has to send data to the MN's HA and the HA then forwards the data to the MN. The MN can send data directly to the CN - creating a triangle. In Mobile IPv4 Route Optimisation eliminates this.
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What is a Gateway Foreign Agent (GFA)? |
Hierarchical Mobile IPv4 Terminology A Foreign Agent which has a publicly routable IP address A GFA may be placed in or near a firewall |
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What is a Regional Foreign Agent (RFA)? |
Hierarchical Mobile IPv4 Terminology
A Foreign Agent which may be the target of a request for regional registration |
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What is a Regional Registration? |
Hierarchical Mobile IPv4 Terminology
An MN performs registration locally at the visited domain, by sending a Regional Registration Request to a GFA, and receiving a Regional Registration Reply in return |
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What is a Local Care-of Address (LCoA)? |
Hierarchical Mobile IPv4 Terminology
A Care-of Address which offers local connectivity to an MN within a given domain |
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Describle the process of Hierarchical Mobile IPv4 |
NOT SURE IF THIS IS CORRECT!! MN moves to a foreign domain MN exchanged agent discovery messages with RFA MN registers its CoA = LCoA with the RFA and GFA The GFA forwads the registration of the CoA to the HA The HA sends a registration reply to the GFA The GFA sends the registration reply to the MN through the RFA Data sent from CN to HA is sent to the MN through the GFA and the RFA |
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How does Mobile IPv6 work? |
MN moves from home network to foreign network (handover) BU is sent from the MN to the HA with its HoA and its current CoA BU ACK sent from the HA to the MN Data sent from CN to HoA of MN, HA forms tunnel to MN's CoA and sends data MN sends BU + Home Option to the CN CN ACKs this and sends a BU Request MN sends a BU which the CN ACK Data can then be send directly from the CN to the MN's CoA |
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What are some features of Mobile IPv6? |
Mobile IPv6 eliminates the problem of "triangle routing" present in Mobile IPv4 protocol In Mobile IPv6, there is no longer any need to deploy special routers as "Foreign Agents " Most packets sent to an MN while away from home in Mobile IPv6 are sent using an IPv6 routing header rather than IP encapsulation The movement detection is easier New destination options are introduced Mobile IPv6 is more robust and secure |
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What is Home Agent Discovery Address in Mobile IPv6? |
It is a mechanism used by the MN when it is away from home to discover the address of one or more routers serving as HA It may be necessary when the home link has been reconfigured Some ICMP messages are used in this mechanis: Home Agent Address Discovery Request Home Agent Address Discovery Reply |
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What is a Home Agent Address Discovery Request? |
May be used by the MN to initiate the home address discovery mechanism when attempting a home registration The MN sends a Home Agent Address Discovery Request message to the "Mobile IPv6 Home-Agents" anycast address for its own home subnet prefix It is an ICMP message |
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What is a Home Agent Address Discovery Reply? |
It is a used by one HA to respond to the MN’s Home Agent Address Discovery Request It is an ICMP message It contains a list of the routers on the mobile node's home link serving as home agents |
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What are the four destination options defined for Mobile IPv6 and what are their purpose? |
Binding Update Binding Acknowledgement Binding Request Home Address They are used to allow IPv6 nodes to communicat with a mobile node They are used to dynamically learn and cache the mobile node’s binding |
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What is Binding? |
A binding is the association between the mobile node’s registered care-of address and its home address |
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Describe the Mobile IPv6 Binding Update Option (BU)
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It is used by the mobile node to notify a correspondent and its home agent of its current binding The BU is used to register the mobile node’s CoA with the HA The BU can be sent in a separate packet or a data packet Any packet that contains an BU must be authenticated Any packet that includes an BU option must also include a Home Address option |
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Describe the Mobile IPv6 Home Address Option |
Its is sent by the MN when it is away from home It is used by the MN to notify a correspondent node of the mobile node’s HoA It makes the use of the CoA transparent either to the correspondent or to high-level applications |
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Describe the Mobile IPv6 Binding Acknowledgement Option |
Its is by a correspondent node to acknowledge the receipt of an BU when the MN set the Acknowledge bit (A=1) The correspondent node may include this destination option in any existing packet being sent to the MN or send it in a packet by itself |
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Describe the Mobile IPv6 Binding Request Option |
Its is used to request a mobile node’s binding from the MN It is used by a correspondent node to refresh a binding cache when the MN’s binding is close to expiration The correspondent node may include this destination option in any existing packet being sent to the MN or send it in a packet by itself When the MN receive a this option, it should reply with an BU option |
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What are the three conceptual data structures defined in the Mobile IPv6 Protocol? |
Binding Cache (BC) Binding Update List (BUL) Home Agents List (HAL) |
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What is Binding Cache (BC) |
Used in Mobile IPv6 It is maintained by each IPv6 node It contains binding information of other nodes A node with multiple IPv6 addresses should maintain separate BC Before sending a packet, the BC is searched Each BC entry contains the following fields : Home address of the MN The MN’s CoA, Lifetime A home registration flag A MN router flag Home address routing prefix length Sequence Number Recent usage information The Binding Security Association When the BC is full, some entries can be deleted |
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What is a Binding Update List (BUL)? |
Used in Mobile IPv6 It is maintained by each MN node It includes all the most recent binding update sent by the MN to: all its correspondent nodes the MN’s home agent a home agent on the link on which the MN's previous CoA is located Each BUL entry contains the following fields : IPv6 address of the correspondent node The MN’s home address or the previous CoA The CoA address of the BU The initial lifetime of the BU The remaining lifetime of the BU The Sequence Number The time at which a BU was last sent to this destination The state of any retransmissions needed for this BU A permission denied flag |
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What is a Home Agents List (HAL)? |
Used in Mobile IPv6 It is maintained by each MN node and HA node It is similar to the Default Router List conceptual data structure maintained by each host for Neighbor Discovery Each HA maintains a separate HAL for each link on which it is serving as a HA It is used in the Home Agent Address Discovery mechanism Each HAL entry contains the following fields : The link-local @ of the HA [learned from the Router Advertisement (H=1)] One or more global IP addresses for the HA The remaining lifetime of this entry The preference for the HA |
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What is Network Renumbering in Mobile IPv6?
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Home subnet renumbering can occur when switching to a new network service provider In renumbering, new prefixes and addresses can be introduced for the subnet and old ones can be deprecated and removed Mobile nodes away from home can lose their home addresses Home agents can be replaced by another one serving the same role Problem: How to guarantee the mobile node identity?! Solution: Introduction of two new ICMP messages: ICMP Mobile Prefix Solicitation ICMP Mobile Prefix Advertisement |
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What is the ICMP Mobile Prefix Solicitation message? |
Used in Mobile IPv6 to combat the network renumbering problem. It is sent by a MN to its HA while away from home The MN solicitates a Mobile Prefix Advertisement The MN can configure its home address(es) or update address(es) according to changes in prefix information supplied by the home agent |
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What is the ICMP Mobile Prefix Advertisement message? |
Used in Mobile IPv6 to combat the network renumbering problem. It is sent by a HA to a HA to response Mobile Prefix Solicitation It is used to distribute prefix information about the home link while the mobile node is traveling away from the home Each message contains one or more prefix that should be used by the MN to configure its home address(es) It is secured by using IPsec |
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How does mobile IPv6 Fast Handover work? |
I have no idea! the diagram on the slide is confusing :( |
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What is Hierarchical Mobile IPv6?
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Similar to the HMIPv4 The GFA is substituted by a Mobility Anchor Point Enables Fast Handover between Access Routers by using Fast Binding Update messages |
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What is a Mobile Network (NEMO)? |
A Mobile Network is a network segment or subnet which can move and attach to arbitrary points in the routing infrastructure NEMO protocol is an extension of the Mobile IPv6. It enables a whole network to attach to different points in the Internet Transparency: Every node within the moving network continues its sessions normally as the network moves |
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What is a Mobile Router? |
Used with NEMO (I think??) Performs agent discovery Performs registration Routing for mobile networks Mobile router supports both non-mobile IP clients as well as mobile IP-aware clients Mobile networks are stub networks hanging off the mobile router Home Agent (HA) : Process registration & Routing to mobile networks HA knows which Mobile Node (MN) is really a mobile router (MR) HA associates mobile networks to MR |
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What are some applications for Mobility? |
Wireless ISP Wireless Campus Network Moving Networks (e.g. public transport, army, emergency services) Smart Car E-Wheelchair Multimedia and Multicast Applications (e.g. push media, news feeds etc.) |
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What is Multi-Homing? |
A mobile device can be within the range of multiple radio access technologies Next generation mobile devices will be equipped with multiple network interfaces (Ethernet, WiFi, WiMax, GPRS, etc.) A mobile device may need to switch from one radio access technology to another to optimise the quality of its connection For Quality of Service reasons, wireless traffic may be split across different network connections or devices Multi-homing can occur on the mobile devices or the network equipment (e.g. Access Points, Gateways, etc.) |
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What is a Multi-Homed Nontransit Autonomous System? |
Multi-homed AS have more than one exit point to outside networks A Nontransit AS does not allow transit traffic to go through it It advertises only its own routes to both providers, but does not advertise routes it learned from one provider to another Traffic and route information can go from one provider to the internal network (AS) but in cannot go to the other providers. |
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When is Multi-Homing required? |
Need for Ubiquitous Access to the Internet Moving from a private WLAN to a public wireless metropolitan area network (WMAN) network using WiMax in a seamless way Need to Redirect Established Sessions Moving an established video call from 3G cellular network to WiFi connection to optimize the quality of the video Need to Set Up Preferences The WLAN service is used for non-confidential activities, such as web-browsing and video-conferencing, and the dial-up connection. 3G is used for secure communications Need to Select the Best Access Technology Need to dispatch flows to particular access media according to traffic characteristics or preferences Need for Reliability Need of bicasting to transmit critical data (e.g. operation via long-distance medical system) Need to Accelerate Transmission Multiple WLAN interfaces are used to connect to different access points, and thus different download flows can be distributed between the wireless interfaces |
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What are two ways Multi-Homing can be configured? |
One Interface, Multiple Prefixes Multiple Interfaces |
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Explain Multi-Homing: One Interface, Multiple Prefixes and what are the advantages of it? |
Configuration One access point connected to two access routers (gateways). Each access router is configured to advertise distinct network prefixes by Router Advertisements on the link and can be used as default router. The two routers can be used for redundancy or load sharing. Advantages Each wireless node can obtain two IP addresses (one from R1 and one from R2) Flows can be redirected Flows can be shared |
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Explain Multi-Homing: Multiple Interfaces and what are the advantages of it? |
Example A typical example is a node with two interfaces, each one on a different technology (e.g. a WLAN 802.11b interface and a 3GPP GPRS interface) A node may use its multiple interfaces (WiFi and GPRS) either alternatively or simultaneously Advantages It is easier to guarantee ubiquitous access when the node has multiple interfaces since distinct technologies may be available at a given time according to the location and administrative policies In case of a change in user preferences, or a failure, flows might need to be redirected from one interface to another one Reliability: two level of redundancy Load balancing can be achieved on the node if several interfaces are used simultaneously |
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What is Vertical Handover and what is Horizontal Handover? |
Vertical Handover is when a device changes its point of access to a new technology (e.g. going from a WLAN connection to a 3G GPRS connection). Horizontal Handover is when a device changes its point of access within the same technology (e.g. connected to another AP within the same WLAN or connecting to a different WLAN). |
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What are some issues with Multi-Homing? |
Address Selection Transport sessions with multihoming capabilities such as SCTP may be able to continue easily since SCTP has built-in transmission rate control mechanisms to take into account the differences between two paths Failure Discovery and Recovery Delay Change of Traffic Characteristics The change of path for a specific session (e.g. due to change of interface) may cause changes on the end-to-end path characteristics (higher delay, different MTUs, etc). Transparency Change of IP address: need of Mobile IP or NEMO (for routers) |
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What is Wireless Domain Services (WDS)? |
A WDS provides fast, secure roaming for client devices (Layer 2 Mobility) Fast, secure roaming provides rapid re-authentication when a client device roams from one access point to another, preventing delays in voice and other time-sensitive applications. An access point configured as the WDS device supports up to 60 participating access points. A WLSM-equipped switch supports up to 300 participating access points. Layer 3 Mobility can be added using Mobile IP protocol |
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What tasks does a WDS device perform on a WLAN? |
Advertises its WDS capability and participates in electing the best WDS device for your wireless LAN. When you configure your wireless LAN for WDS, you set up one device as the main WDS candidate and one or more additional devices as backup WDS candidates. If the main WDS device goes off line, one of the backup WDS devices takes its place. Authenticates all access points in the subnet and establishes a secure communication channel with each of them. Collects radio data from access points in the subnet, aggregates the data, and forwards it to the WLSE device (wireless LAN solution engine, controller) on your network. Registers all client devices in the subnet, establishes session keys for them, and caches their security credentials. When a client roams to another access point, the WDS device forwards the client's security credentials to the new access point. |
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In what ways does an AP interact with a WDS device on a WLAN? |
Discover and track the current WDS device and relay WDS advertisements to the wireless LAN. Authenticate with the WDS device and establish a secure communication channel to the WDS device. Register associated client devices with the WDS device. Report radio data to the WDS device. |
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What is the sequence of messages used in a WDS WLAN when a roaming devices changes AP connection? |
Roaming client devices sends a Resassociation Request to the AP The AP sends a Pre-Registration Request to the WDS device The WDS devices sends a Pre-Registration Reply to the AP The AP sends a Reassociation Response to the roaming client device. |
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What are some features of the Control and Provisioning of Wireless Access Points (CAPWAP) Protocol? |
The CAPWAP protocol is designed to be flexible, allowing it to be used for a variety of wireless technologies It is an interoperable protocol that enables an Access Controller (AC) to manage a collection of Wireless Termination Points (WTPs). CAPWAP assumes a network configuration consisting of multiple WTPs communicating via the Internet Protocol (IP) to an AC |
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What are the goals of the CAPWAP Protocol? |
To centralize the authentication and policy enforcement functions for a wireless network. The AC may also provide centralized bridging, forwarding, and encryption of user traffic. To enable shifting of the higher-level protocol processing from the WTP. This leaves the time-critical applications of wireless control and access in the WTP, making efficient use of the computing power available in WTPs To provide an extensible protocol that is NOT bound to a specific wireless technology. Extensibility is provided via a generic encapsulation and transport mechanism, enabling the CAPWAP protocol to be applied to many access point types in the future, via a specific wireless binding |
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What are the two CAPWAP Operations Modes? |
Split MAC Mode In Split MAC mode, all L2 wireless data and management frames are encapsulated via the CAPWAP protocol and exchanged between the AC and the WTP The wireless frames received from a mobile device are directly encapsulated by the WTP and forwarded to the AC Local MAC Mode The Local MAC mode of operation allows for the data frames to be either locally bridged or tunnelled as 802.3 frames |
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What is LWAPP? |
Lightweight Access Point Protocol Cisco proprietary protocol Is compatible with the CAPWAP protocol |
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What are the differences between an Autonomous AP and a LWAPP AP? |
Autonomous AP Full 802.11 protocol Access router Managed device CLI RADIUS, 802.1X, etc. Secrets on device LWAPP AP Real-time 802.11 protocol Remote interface No secrets on device Managed via controller No direct access RF Spectrum Analyzer Intrusion Detection System (IDS) |
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What are the LWAPP Controller Responsibilities? |
Authentication/Policy Enforcement Mobility Management RF Management |
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What are the nodes found in Wireless Mesh Networks? |
Mesh Routers Mesh Gateways Mobile Clients Stationary Clients Printers, Servers etc.. |
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What is the name given to the coverage area (i.e. the topology) in a mesh network? |
Mesh Cloud |
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What are the link types found in Wireless Mesh Networks? |
Intra-mesh wireless links (between mesh routers) Stationary client access links Mobile client access links Internet access links |
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What are the standards relating to Wireless Mesh Networks? |
IEEE 802.11s (main one) IEEE 802.15.1 IEEE 802.15.4 IEEE 802.15.5 IEEE 802.16a |
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In Wireless Mesh Networks, what are the mesh gateways? |
Connection to the internet Multiple interfaces (wired & wireless) Mobility Stationary (e.g. rooftop) – most common case Mobile (e.g., airplane, busses/subway) Serve as (multi-hop) “access points” to user nodes Relatively few are needed, (can be expensive) |
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In Wireless Mesh Networks, what are mesh routers? |
Main routers that make up the wireless mesh network. At least one wireless interface. Mobility Stationary (e.g. rooftop) Mobile (e.g., airplane, busses/subway). Provide coverage (acts as a mini-cell-tower). Do not originate/terminate data flows Many needed for wide areas, hence, cost can be an issue. |
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In Wireless Mesh Networks, what are mesh clients? |
The users of the mesh network. Can be laptops, mobiles, PCs, servers etc. Typically one interface. Mobility Stationary(e.g. PC) Mobile(e.g. Laptop) Connected to the mesh network through wireless routers (or directly to gateways) The only sources/destinations for data traffic flows in the network. |
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In Wireless Mesh Networks, what are the access links? |
The mesh client - mesh router links. Wired Bus (PCI, PCMCIA, USB) Ethernet, Firewire, etc. Wireless 802.11x Bluetooth Proprietary Point-to-Point or Point-to-Multipoint If properly designed is not a bottleneck. |
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In Wireless Mesh Networks, what are the backbone links? |
Links between mesh routers. Wireless 802.11x Proprietary Usually multipoint to multipoint Sometimes a collection of point to point Often the bottleneck |
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In Wireless Mesh Networks, what are the backhaul links? |
Mesh gateway to internet links. Wired Ethernet, TV Cable, Power Lines Wireless 802.16 Proprietary Point to Point or Point-to-Multipoint If properly designed, not the bottleneck |
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How does data flow in Wireless Mesh Networks? |
In most applications the main data flows from the mesh client, through the mesh routers to the mesh gateway and out to the internet. In most application only a small amount of data flows from a mesh client through the mesh routers to another mesh client. |
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Compare Ad-Hoc Networks and Wireless Mesh Networks |
Ad-hoc Nodes are wireless, possible mobile Doesn't normally rely on existing infrastructure Most traffic is user-to-user Wireless Mesh Networks Multihop Nodes can be wireless (some mobile) or fixed Relies on infrastructure Most traffic is user-to-gateway |
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Compare Wireless Sensor Networks and Wireless Mesh Networks |
Wireless Sensor Networks Bandwidth is limited (tens of kbps) In most applications, fixed nodes Energy efficiency is an issue Resource constrained Most traffic is user-to-gateway Wireless Mesh Networks Bandwidth is generous (>1Mbps) Some nodes mobile, some fixed Normally not energy limited Resources are not an issue Most traffic is user-to-gateway |
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What are some applications for Wireless Mesh Networks? |
Broadband Internet Access Extended WLAN Coverage Mobile Internet Access Emergency Response Layer 2 Connectivity Military Communications Community Networks Remote Monitoring and Control Public Transportation Internet Access Multimedia Home Networking |
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What are some Wireless Mesh Networks research topics? |
Smart Antennas (L1) Transmission Power Control (L1) Multiple Channels (L2) Routing (L3) Fairness and QoS (L3) Provisioning Security Network Management Geo-location |
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What are some challenges of Wireless Mesh Networks Routing? |
Scalability Overhead is an issue in mobile WMNs. Fast route discovery and rediscovery Essential for reliability. Mobile user support Seamless and efficient handover Flexibility Work with/without gateways, different topologies QoS Support Consider routes satisfying specified criteria Multicast Important for some applications (e.g., emergency response) |
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Which IEEE Standard relates to Wireless Sensor Networks? |
IEEE 802.15.4 |
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What is the IEEE 802.15.4 Standard? |
IEEE 802.15.4 is a standard for low-power, low data rate wireless communication between small devices. 802.15.4 is not the same thing as ZigBee 802.15.4 is a MAC and PHY layer protocol (OSI layers 1 and 2). Use the license-free band ISM (783 / 868 / 915 MHz – 2,4 GHz) ZigBee is a Network Layer (OSI layer 3) Protocol which sits on top of IEEE 802.15.4 : several layer 3 protocols which can make use of 802.15.4 |
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Which higher-level protocols make use of the IEEE 802.15.4 standard? |
Zigbee Zigbee Alliance's mesh networking protocol MiWi Mesh and MiWi P2P Microchip's proprietary mesh and P2P protocols 6LoWPAN IPv6 over 802.15.4 WirelessHART Industrial Automation ISA100.11a Manufacturing, Control, Automation |
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What are some characteristics of the IEEE 802.15.4 standard? |
Data Rate : Up to 250 kb/s depending on band and mode MTU : 127 Bytes per frame (including headers) IEEE 802.15.4g is “likely” to bring a 2047-byte MTU |
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What are the types of devices defined in the IEEE 802.15.4 standard? |
Full Function Device (FFD) – Can talk to all types of devices – Supports full protocol – Perform routing (Mesh-under routing) Reduced Function Device (RFD) – Can only talk to an FFD – Lower power consumption – Minimal CPU/RAM required |
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Describe the IEEE 802.15.4 Topology |
Devices are segregated into Personal Area Networks (PAN) Devices can communicate between PANs (inter-PAN) or within their own PAN (intra-PAN) Each PAN has a PAN Identifier : 16-bit number Broadcast PAN ID is 0xffff (all PANs) |
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Describe IEEE 802.15.4 Addressing |
Short and long addresses can be used or mixed Each device has two addresses : – Long Address 64-bit globally unique device ID – Short Address 16-bit PAN-specific address (Optional) Assigned by the PAN coordinator (FFD) at association time |
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Describe IEEE 802.15.4 Routing |
Supports 3 types of topologies Star Cluster Tree based Mesh : While 802.15.4 is designed with meshing in mind, it is not part of the 802.15.4 standard, and left to the network layer |
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How are devices grouped together in Wireless Sensor Networks? |
Devices are grouped into clusters.
Each cluster has a unique cluster ID A cluster head is elected for each cluster Once the max. number of associations for a cluster has been reached a new cluster is formed, with its own cluster ID, cluster head etc. |
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What changes have been made to IPv6 Packet Headers from IPv4 Packet Headers? |
Version, Source Address and Destination Address fields have remained the same. IHL, Identification, Flags, Fragment Offset, Header Checksum, Options and Padding fields have been removed. Type of Service, Total Length, Time to Live and Protocol fields have changes position and become Traffic Class, Payload Length, Hop Limit and Next Header. Flow Label is a new field in IPv6 headers. |
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What are IPv6 Aggregatable Global Unicast Addresses? |
Addresses for generic use of IPv6 Structured as a hierarchy to keep the aggregation |
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What are some issues with using IPv6 over IEEE 802.15.4? |
MTU issues: – IPv6 has an MTU requirement of 1280 bytes. – 802.15.4 has an MTU of 127 bytes. Header issues 802.15.4 maximum frame overhead of 25 bytes Link-layer security can be as high as 21 bytes 40-byte IP header 8-byte UDP header 33 bytes remaining for actual data (127-25-21-40-8 = 33) Solution ? How to insert a packet of 1280 bytes into a packet of 127 bytes ! The solution: 6LoWPAN (RFC 4944 and RFC 6282) Adaptation layer between IPv6 and IEEE 802.15.4 |
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What is 6LoWPAN? |
IPv6 over Low Power Wireless Personal Area Networks Solves some of the problems of using IPv6 with IEEE 802.15.4 standard for wireless sensor networks. |
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What are the aims of 6LoWPAN? |
Adjust the IPv6 network to the performances of smart objects Compression of the IPv6 and UDP headers Multiple compression schemes for IPv6 addresses Transparent fragmentation of 1280B packets to fit 127B frames Optimization of the IPv6 Neighbour Discovery Protocol |
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How does data flow from a 6LoWPAN Network to servers on the internet? |
The 6LoWPAN network is connected to a gateway which creates a tunnel for the 6LoWPAN traffic over the IPv4 Ethernet to the Internet where connections are made to servers. I think! Not 100% sure |
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What are the two types of nodes within a 6LoWPAN Network? |
End Node : These nodes have sensors integrated and are used to gather the information and send to the GW. They create a mesh network among them, forwarding the packets of other nodes in order to make the information reach the GW. Each End Node is equipped with a 6LoWPAN radio, sensors and a battery. Gateway : This node takes the information sent by the End Nodes and send it to the Tunnelling IPv4 / IPv6 server by using the Ethernet IPv4 interface. Each GW Node is equipped with a 6LoWPAN radio and a Ethernet interface and a battery. |
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What is the purpose of 6LoWPAN Packet Compression? |
To compress the network packet header down to 3 bytes from 40 bytes. This is done by eliminating all fields in the IPv6 header that can be derived from the 802.15.4 header in the common case Source address : derived from link address Destination address : derived from link address Length : derived from link frame length Traffic Class & Flow Label : zero Next header : UDP, TCP, or ICMP Additional IPv6 options follow as options |
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What does the 6LoWPAN 1st Byte signify? |
00 - not a LoWPAN fram 01 - LoWPAN IPv6 Addressing header 10 - LoWPAN Mesh header 11 - LoWPAN Fragmentation header |
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What are some research areas for 6LowPAN? |
Optimised routing protocol over sensor network : Mesh-under routing (with or without QoS) Optimised Neighbor Discovery (Tuning, Adaptation, Energy awarness, etc.) Hybrid addressing for PAN coordinator (short and long addresses allocation, address aggregation, election process (priorities, probabilistic, etc.), hierarchical addressing, mobility consideration (mobile wireless sensor network) Broadcast and Multicast support (Tree formation, maintenance and migration) |
