Wireless Networks and Protocols

Transcription

1 WNP-MPR-mip-mesh 1 Wireless Networks and Protocols MAP-Tele Manuel P. Ricardo Faculdade de Engenharia da Universidade do Porto

2 WNP-MPR-mip-mesh 2 Topics Scheduled for Today Convergence and interoperability of wireless systems: bringing all together» 4G wireless networks» 3GPP approach» Mobile IPv6 approach Basics on Mobile IP 3GPP plans for adopting Mobile IPv6 Media Independent handover» Wireless mesh Basics on ad-hoc networks The IEEE mesh networks» Research issues

3 WNP-MPR-mip-mesh 3 Basics on Mobile IP How to move between IP networks while maintaining a connection active? What are the differences between MIPv4 and MIPv6? How is routes optimization in MIPv6 How does the Dual Stack MIPv6 work?

4 Mobile IPv4 WNP-MPR-mip-mesh 4

5 WNP-MPR-mip-mesh 5 Motivation IP datagram forwarding is based on IP destination address IP network address physical network Changing network changing IP address How to implement mobility at the IP layer? Possible solution» Register new IP address near the DNS server» Problems DNS registration takes time TCP connections will break

6 WNP-MPR-mip-mesh 6 Mobile IPv4 - Terminology MN, Mobile Node HA, Home Agent registers MN location FA, Foreign Agent agent in the visited network COA, Care-of Address MN s IP address in the visited network CN, Correspondent Node host which communicates with the MN

7 WNP-MPR-mip-mesh 7 Example HA MN home network router Internet mobile end-system (physical home network for the MN) router FA foreign network CN (current physical network for the MN) end-system router

8 WNP-MPR-mip-mesh 8 Data transference to MN HA 2 MN home network Internet 3 receiver FA foreign network CN sender 1 1. Sender sends to the IP address of MN, HA intercepts packet 2. HA tunnels packet to COA (FA) by encapsulation 3. FA forwards the packet to the MN

9 WNP-MPR-mip-mesh 9 Data transference from MN HA 1 MN home network Internet sender FA foreign network CN receiver 1. Sender sends to the IP address of the receiver as usual, FA works as default router

10 WNP-MPR-mip-mesh 10 Mobility phases COA home network router HA router FA MN Internet foreign network CN router home network router HA 2. router FA MN Internet foreign network 1. CN router

11 WNP-MPR-mip-mesh 11 MN Agents communication MN identifies the network» Mobility agents send regularly messages to their networks ICMP Router Advertisement messages» MN listens messages; determines the network Its home network, or A visited network MN obtains new address the CoA In the visited network, after obtaining CoA, MN» MN sends COA to HA (via FA) new location registered at the HA» At the home network HA assumes the MN home IP address Packets destined to the MN IP home address are intercepted by HA and tunnelled to the MN (CoA address)

12 ICMP Router Advertisment WNP-MPR-mip-mesh 12 Mobility Extensiom type code checksum #addresses addr. size lifetime router address 1 preference level 1 router address 2 preference level 2... type length sequence number registration lifetime R B H F M G r T reserved COA 1 COA 2... R registration required B FA busy H agent is HA F agent is FA M minimal encaspulation accepted G GRE encapsulation accepted r not used T FA supports reverse tunneling Message sent by mobility agents (HA and FA)

13 WNP-MPR-mip-mesh 13 To think about Can we remove the Foreign Agent from MIPv4? What are the consequences of it?

14 WNP-MPR-mip-mesh 14 MN registration in the Home Agent MN HA registration request MN FA HA registration reply registration request registration request t t registration reply registration reply Co-located address Tunnel will end at the MN Address obtained by DHCP, for instance

15 WNP-MPR-mip-mesh 15 Registration messages port UDP 434 Type registration request, registration reply S Maintain old binding B broadcast messages shall be forwarded D co-located address M minimal encapsulation accepted G GRE encapsulation accepted r not used T FA supports reverse tunneling x - ignored type S B DMG r T x lifetime home address home agent COA identification extensions...

16 WNP-MPR-mip-mesh 16 Tunnels original IP header original data new IP header new data outer header inner header original data

17 WNP-MPR-mip-mesh 17 IP in IP (mandatory) ver. IHL TOS length IP identification flags fragment offset TTL IP-in-IP IP checksum IP address of HA Care-of address COA ver. IHL TOS length IP identification flags fragment offset TTL lay. 4 prot. IP checksum IP address of CN IP address of MN TCP/UDP/... payload Tunnel HA COA

18 WNP-MPR-mip-mesh 18 To think about What is NAT (Network Address Translation)?

19 NAT Network Address WNP-MPR-mip-mesh 19 Translation

20 WNP-MPR-mip-mesh 20 To think about Does MIPv4 work when MN has a private CoA address?

21 Mobile IPv6 WNP-MPR-mip-mesh 21

22 WNP-MPR-mip-mesh 22 Mobile IPv6 working principles Differences to MIPv4» No ForeignAgent» Registration signalling (HomeAddress CareOfAddress ) Sent as an IPv6 extension header Mobility Header Binding relations (HomeAddress CareOfAddress ) also in the CNs Binding messages» BindingUpdate MN informs HA/CN of its CareOfAddress» BindingAcknowledgement Received by MN. Confirms BindingUpdate» BindingRefreshRequest Sent by HA/CN. Requests MN to refresh binding

23 WNP-MPR-mip-mesh 23 Binding MN moves to a visited network MN auto-configures new address COA COA network prefix == prefix of the visited network MN asks for registration of COA in HA MN sends IPv6 packet with BindingUpdate (extension header) HA registers MN and replies with BindingAcknowledgment Tunnel MN - HA HA, in home networks Intercepts packet to MN Sends packet to COA; by tunnel MN Sends packet in tunnel to HA

24 CoA autoconfiguration, in the WNP-MPR-mip-mesh 24 visited network MN» Listens RouterAdvertisment messages In mobility routers up to 50 msg/s Obtains network prefix» Builds address in the visited network, the CareOfAddress Routing Prefix MAC address DHCPv6 may be used by MN to obtain CoA

25 WNP-MPR-mip-mesh 25 Route optimization When MN receives a tunnelled packet» it sends BindingUpdate to CN HomeAddress CareOfAddress binding also at the CN Packets exchanged directly between MN e CN

26 WNP-MPR-mip-mesh 26 Route optimization IPv6 packets in direction CN MN» CN» MN Before sending a packet to MN, reads its Bindings cache Is there is no entry packet sent as usual If there is an entry Sends packet to CareOfAddress (destination address = CareOfAddress) Includes in the packet a RoutingHeader having 2 hops (list of addresses to be visited) 1º hop CareOfAddress; 2º hop MN HomeAddress Receives packet in CareOfAddress Forwards packet to itself (MN home address) IPv6 packets in the MN CN direction Source address = CareOfAddress Inclusion of DestinationHeader with information on HomeAddress CN replaces HomeAddress in the packet source address so that the socket structure may contain the correct information HomeAddress

27 Packet sent from S to D, passing WNP-MPR-mip-mesh by 27 I1, I2, I3 As the packet travels from S to I1: Source Address = S Hdr Ext Len = 6 Destination Address = I1 Segments Left = 3 Address[1] = I2 Address[2] = I3 Address[3] = D As the packet travels from I1 to I2: Source Address = S Hdr Ext Len = 6 Destination Address = I2 Segments Left = 2 Address[1] = I1 Address[2] = I3 Address[3] = D As the packet travels from I2 to I3: Source Address = S Hdr Ext Len = 6 Destination Address = I3 Segments Left = 1 Address[1] = I1 Address[2] = I2 Address[3] = D As the packet travels from I3 to D: Source Address = S Hdr Ext Len = 6 Destination Address = D Segments Left = 0 Address[1] = I1 Address[2] = I2 Address[3] = I3

28 WNP-MPR-mip-mesh 28 ping ping cn ha mn router novo mn no' moves > radv > binding update < binding ack > echo request =============================================> echo reply < ==============================================+ home test init < ==============================================+ care of test init < care of test > home test =============================================> binding update < binding ack > echo request > echo reply <

29 WNP-MPR-mip-mesh 29 Dual Stack Mobile IPv6 (DSMIPv6)

30 WNP-MPR-mip-mesh 30 DSMIPv6 DS-HA Extends MIPv6 to allow» registration of IPv4 addresses» transport of both IPv4 and IPv6 packets in the tunnel to MN-HA» MN to roam over IPv6 and IPv4 (public and private) networks Assumes» MN and HA are both IPv4 and IPv6-enabled» Uses only MIPv6 signalling

31 WNP-MPR-mip-mesh 31 DSMIPv6 Mobility Management Visited network supports IPv6» MN sends regular MIPv6 BindingUpdate» MN registers IPv6 CoA to HA» HA creates two binding cache entries, both pointing to MN-CoA-IPv6 MN-home-address-IPv6 MN-CoA-IPv6 MN-home-address-IPv4 MN-CoA-IPv6» HA tunnels traffic to MN-CoA-IPv6

32 WNP-MPR-mip-mesh 32 DSMIPv6 Mobility Management Visited network supports IPv4 only - public addresses» MN tunnels MIPv6 BindingUpdate message to the HA IPv4 address» HA creates two binding caches entries, both pointing to the MN-CoA-IPv4 MN-home-address-IPv6 MN-CoA-IPv4 MN-home-address-IPv4 MN-CoA-IPv4» All the packets addressed to MN-home-addresses (IPv4 or IPv6) are encapsulated in an IPv4 tunnel HAv4 MN-CoA-IPv4

33 WNP-MPR-mip-mesh 33 DSMIPv6 Mobility Management Visited network supports IPv4 only - private addresses» HA listens in an UDP port, over a public IPv4 address» MN tunnels MIPv6 BindingUpdate message to HA IPv4/port addresses» HA creates two binding caches entries, both pointing to the public-mn-coa-ipv4/port (recall NAT) MN-home-address-IPv6 public-mn-coa-ipv4/port MN-home-address-IPv4 public-mn-coa-ipv4/port» At the HA, the packets addressed to MN home addresses (IPv4 or IPv6) are first encapsulated in UDP packet (port to port), then encapsulated in an IPv4 tunnel ending at the public-mn-coa-ipv4 (recall the NAT functionality) IPv4/IPv6 UDP IPv4

34 WNP-MPR-mip-mesh 34 To think about Is the IPv4/IPv6 packet received in (linux) user or kernel space? IPv4/IPv6 UDP IPv4 How can the contents of this packet be delivered to, for instance, the Web-browser running on top of TCP/IPv4?

35 WNP-MPR-mip-mesh 35 DSMIPv6 Route Optimization Visited network supports IPv6 similar to MIPv6 Visited network supports IPv4 only not possible; communication always through the Home Agent Not possible for traffic addressed to the Mobile Node's IPv4 home address

36 WNP-MPR-mip-mesh 36 3GPP plans for adopting Mobile IP What MIP based solutions are currently being studied in 3GPP? How are these solutions expected to work?

37 3GPP-WLAN Interworking WNP-MPR-mip-mesh and 37 3GPP Systems Plans for Release 8 Requirements» Smooth migration from legacy network with minimal impacts on dual mode UEs, I-WLAN and 3GPP systems» Architecture, functions and procedures shall be re-used» Both IPv4 and IPv6 addresses shall be supported» Service continuity between 3GPP PS network and I-WLAN with IP address preservation Possible solution based on DSMIPv6» 3GPP TS , TS Conclusions based on the SAE report may lead to other solutions» See 3GPP TR

38 Home Mobility Service WNP-MPR-mip-mesh 38 Architecture Home Agent function at home PLMN 3GPP AAA Server Wx HSS WLAN AccessNetwork Wn WAG Wp PDG/ AR H3 H2 Ww UE Wu H1 HA HGi External PDN Uu/Um H3 GERAN/UTRAN Iu_ps/Gb SGSN Gn GGSN/ AR

39 Visited Mobility Service WNP-MPR-mip-mesh 39 Architecture Home Agent function outside the hplmn 3GPP AAA proxy Wd* 3GPP AAA server Wx HSS WLAN Access Network Wn WAG Wp PDG/ AR Ww UE Wu H1 H3 HA H2 HGi External PDN Uu/Um H3 GERAN/UTRAN Iu_ps/Gb SGSN Gn GGSN/ AR VPLMN HPLMN

40 WNP-MPR-mip-mesh 40 H1 PDN Attach UE HA 3GPP AAA 3GPP AAA Proxy Server 1. HA discovery 2. IKEv2 Security Association establishment & IPv6 HoA allocation 2. Auth. & Authorization 3. Binding Update 4. Binding Acknowledgement

41 WNP-MPR-mip-mesh 41 H1 PDN Attach 1. UE discovers the Home Agent (e.g using the DNS service) 2. A security association is established between UE and HA» to secure the DS-MIPv6» HA communicates with AAA infrastructure to complete authentication» HA assigns IPv6 home address/prefix to UE» If HA@ vplmn interaction HA@vPLMN AAA/HSS@hPLMN involves AAA-Proxy@vPLMN 3. UE sends BindingUpdate» UE may request an IPv4 home address from the HA 4. HA replies with BindingAck» HA may assign IPv4 home address to UE

42 WNP-MPR-mip-mesh 42 To think about Why does HA assign home addresses? What about the IP addresses gathered by the UE through the GPRS-attach and IWLAN-attach?

43 Handover from IWLAN to 3GPP WNP-MPR-mip-mesh 43 access 1. UE discovers the GPRS, and decides to transfer sessions to GPRS 2. UE starts GPRS attach procedure, which includes» GGSN selection, IP address assignment to the UE (CoA)» GTP tunnel establishment between UE and GGSN 3. UE sends BindingUpdate message to HA 4. HA sends BindingAck to UE

44 Handover from 3GPP access WNP-MPR-mip-mesh to 44 IWLAN access 1. UE discovers the IWLAN, and decides to transfer sessions to IWLAN 2. UE establishes an IPsec tunnel with PDG, and gets new IP address (CoA) 3. UE sends BindingUpdate via IWLAN 4. DSMIPv6 tunnel established between UE and HA; UE can exchange data through IWLAN UE PDG GGSN HA UE Discovers 3GPP IWLAN access and initiates HO 2. IPsec tunnel establishment IPsec 8. DSMIPv6 Tunnel Tunnel 3. H1 PDN Attach or BU/BA DSMIPv6 8. DSMIPv6 Tunnel tunnel

45 WNP-MPR-mip-mesh 45 UE Initiated Detach 1. UE sends BindingUpdate to HA with Binding-Lifetime = 0 2. HA sends the BindingAck to UE 3. UE tears down security association between UE and HA 4. The HA communicates with AAA infrastructure to tear down the H2 session UE HA 3GPP AAA 3GPP AAA Proxy Server 1. Binding Update 2. Binding Acknowledgement 3. IKEv2 Security Association tear down 4. H2 session termination

46 WNP-MPR-mip-mesh 46 IEEE What other efforts are being developed to help macro mobility? How does the work?

47 WNP-MPR-mip-mesh 47 Problem Characterization Increasing number of interfaces on devices» mostly radio interfaces Device has difficulties in finding its best connection» connection at L2, but not at the network layer» connect to the wrong of many APs available based on signal strength criteria alone Many (vertical) handover mechanisms available Unified mechanism for handover decisions would help new standard, IEEE » common across, at least, 802 media» based on L2 Triggers to make Mobile IP like protocols to work fast» based on media independent information

48 WNP-MPR-mip-mesh 48 The Use Case Internet Headed out of the building Undocked & walking around Desk

49 WNP-MPR-mip-mesh 49 Genesis for Handover Initiation Scope of Handover Preparation Handover Execution Search New Link Setup New Link Transfer Connection Network Discovery Network Selection Handover Negotiation Layer 2 Connectivity IP Connectivity Handover Signaling Context Transfer Packet Reception IEEE helps with Handover Initiation, Network Selection and Interface Activation

50 WNP-MPR-mip-mesh 50 The role of IEEE VCC I-WLAN SAE-LTE 3GPP/2 Inter-working & Handover Signaling IEEE r e IEEE Horizontal Handovers MIP SIP NETLMM FMIP HIPMIPSHOP DNA IETF IP Mobility & Handover Signaling

51 WNP-MPR-mip-mesh Key Services Applications (VoIP/RTP) Link Layer Handover Triggers Connection Management MIH Function Policy State Change Predictive Network Initiated Handover Commands L2 Triggers and Events Handover Management Mobility Management Protocols Smart Triggers Handover Messages Handover Messages Information Service Information Client Initiated Service Network Initiated Vertical Handovers WLAN Cellular WMAN IETF IEEE Network Information Available Networks Neighbor Maps Network Services Protocol and Device Hardware

52 WNP-MPR-mip-mesh 52 L2 Triggers and Events State Change Events» Link Up» Link Down» Link Parameters Change Predictive Events» Link Going Down Network Initiated Events» Load Balancing» Operator Preferences Link Going Down Link Up WLAN Link Up WWAN Link Switch Disconnected Connected Link Down Make before Break Time

53 WNP-MPR-mip-mesh 53 Link Layer Events No Event Type Event Name Description 1 State Change Link Up L2 Connection established 2 State Change Link Down L2 Connection is broken 3 Predictive Link Going Down L2 connection breakdown imminent 4 State Change Link Detected New L2 link has been found 5 State Change Link Parameters Change Change in specific link parameters has crossed prespecified thresholds (link Speed, Quality metrics) 6 Administrative Link Event Rollback Event rollback 7 Link Transmission Link SDU Transmit Status Improve handover performance through local feedback as opposed to waiting for end-to-end notifications 8 Link Synchronous Link Handover Imminent L2 intra-technology handover imminent (subnet change). Notify Handover information without change in link state. 9 Link Synchronous Link Handover Complete Notify handover state

54 Media Independent Information WNP-MPR-mip-mesh 54 Service WMAN WLAN WWAN Information Server Global Network Map List of Available Networks /16/22, GSM, UMTS Link Layer Information - Neighbor Maps Higher Layer Services - ISP, MMS,. Network Type Network Type Network Type GSM GSM n GSM b e SSID/ Cell SSID/ Cell SSID/ ID Cell ID Enterprise Intel NA BSSID BSSID BSSID N/A N/A 00:00: N/A 00:00: NA Operator Operator Operator Oper-1 AT&T Oper-2 AT&T Intel Oper-3 Security Security Security NA NA.11i NA.11i PKM EAP Type NW NW NA NA EAP-PEAP NA EAP-PEAP EAP-PEAP Channel Channel Channel QoS QoS QoS N/A N/A N/A.11e.11e Yes Physical Layer Physical Layer Physical Layer N/A N/A OFDM N/A OFDM OFDM Data Rate Data Rate Data Rate 9.6 Kbps 9.6 kbps Mbps kbps 11 Mbps 40 Mbps

55 WNP-MPR-mip-mesh 55 Information Elements Information Element Description Comments List of networks available Location of PoA Operator ID List all network types that are available given client location Geographical Location, Civic address, PoA ID Name of the network provider E.g., , , GSM, GPRS/EDGE, UMTS networks E.g. GML format for LBS or network management purpose E.g. Could be equivalent to Network ID. Roaming Partners List of direct roaming agreements E.g. in form of NAIs or MCC+MNC Cost Security Quality of Service PoA Capabilities Vendor Specific IEs Indication of costs for service/network usage Link layer security supported Link QoS parameters Emergency Services, IMS Services, etc. Vendor/Operator specific information E.g, Free/Not free or (flat rate, hourly, day or weekly rate) Cipher Suites and Authentication Methods, Technology specific, e.g. WEP in , i, PKM in , etc. 802 wide representation, application friendly Higher Layer Services Custom information

56 WNP-MPR-mip-mesh 56 Handover Types of Handover Based on Control Model Terminal Controlled Terminal Initiated, Network Assisted Network Initiated and Network Controlled Handover Commands for Network Initiated Handovers No Command Name MIHF <> MIHF Description 1 MIH Handover Initiate Client <> Network Initiates handovers and sends a list of suggested networks and suggested PoA (AP/BS). 2 MIH Handover Prepare Network <> Network This command is sent by MIHF on old network to MIHF on suggested new network. This allows the client to query for resources on new network and also allows to prepare the new network for handover 3 MIH Handover Commit Client <> Network In this case the client commits to do the handover based on selected choices for network and PoA. 4 MIH Handover Complete Client <> Network Network <> Network This is a notification from new network PoA to old network PoA that handover has been completed, new PoA has been established and any pending packets may now be forwarded to the new PoA.

57 WNP-MPR-mip-mesh 57 MIH Amendments for Does Not handle Handover Execution No New Mobility Protocols No Redesign of Existing PHY/MAC New items in scope of

58 MIH Amendments for WNP-MPR-mip-mesh 58 No New Mobility Protocols Does Not handle Handover Execution L2.5 No Redesign of Existing PHY/MAC New SAPs in scope of

59 WNP-MPR-mip-mesh 59 Basics on ad-hoc networks What is an ad-hoc network? What are the differences between and ad-hoc wireless network and a wired network? What are the characteristics of the most important ad-hoc routing protocols?

60 WNP-MPR-mip-mesh 60 Ad-Hoc Networks (Layer 3) Auto-configurable networks Having wireless links Mobile nodes dynamic topology Isolated networks or interconnected to Internet Nodes forward traffic Routing protocols A B C

61 IETF MANET - Mobile Ad-hoc WNP-MPR-mip-mesh 61 Networking Mobile Router Mobile Devices Fixed Network Manet Mobile IP, DHCP Router End system

62 WNP-MPR-mip-mesh 62 Route calculation in wired networks Distance vector» Messages exchanged periodically with neighbours» Message indicates reachable nodes and their distance» Algorithm takes long time to converge» Eg. RIP Link state A E B C D» Router informs periodically the other routers about its links state» Every router gets information from all other routers» Lots of traffic» Eg. OSPF 2 F

63 Route calculation in Ad-Hoc WNP-MPR-mip-mesh 63 Netoworks- Characteristics N 1 N 1 N 2 N 3 N 3 N 2 N 4 N 5 N 4 N 5 Ad-hoc network» Dynamic topology Depends on node mobility» Interference time = t good link 1 time = t 2 weak link Radio communications» Asymmetric links Received powers and attenuation unequal in the two directions

64 WNP-MPR-mip-mesh 64 Routing in Ad-hoc Networks Conventional routing protocols Built for wired networks whose topology varies slowly Assume symmetric links In Ad-hoc networks» Dynamic topology information required to be refreshed more frequently energy consumption radio resources for with signaling information» Wireless node may have scarce resources (bandwidth, energy) New routing strategies / protocols for ad-hoc networks 2 type : reactive e pro-active

65 WNP-MPR-mip-mesh 65 To think about How can we avoid a large signaling overhead (number of routing messages) in ad-hoc networks

66 AODV A needs to send packet WNP-MPR-mip-mesh to 66 B

67 WNP-MPR-mip-mesh 67 AODV A sends RouteRequest

68 WNP-MPR-mip-mesh 68 AODV B replies with RouteReply

69 WNP-MPR-mip-mesh 69 AODV - Characteristics» Decision to request a route» Broadcast of Route-request» Intermediate nodes get routes to node A» Route-reply sent in unicast by same path» Intermediate nodes get also route to node B» Routes have Time-to-live, in every node» Needs symmetric graph

70 WNP-MPR-mip-mesh 70 Pro-active routing protocols Routes built using continuous control traffic Routes are maintained Advantages, disadvantages» Constant control traffic» Routes always available Example OLSR (RFC 3626)» OLSR - Optimized Link-State Routing protocol

71 WNP-MPR-mip-mesh 71 OLSR Main functions Detection of links to neighbour nodes Optimized forwarding / flooding (MultiPoint Relaying)

72 OLSR Detecting links to WNP-MPR-mip-mesh 72 neighbour nodes Using HELLO messages All nodes transmit periodically HELLO messages HELLO messages group neighbour by their state

73 OLSR MultiPoint Relaying WNP-MPR-mip-mesh 73 (MPR) MultiPoint Relaying (MPR)» Special nodes in the network» Used to Limit number of nodes retransmiting packets Reduce number duplicated retransmissions Each node selects its MPRs, which must» Be at 1 hop distance» Have symmetric links MPR set selected by a node» Must be minimum» Must enable communication with every 2-hop-away nodes Node is MPR if it has been selected by other node

74 WNP-MPR-mip-mesh 74 OLSR Link State In wired networks, OSPF» Every node floods the network» With information about its links state OLSR does the same, using 2 optimizations» Only nodes associated to MPR are declared in link state message Reduced message length» Only the MPR nodes send link state messages Smaller number of nodes sending messages

75 WNP-MPR-mip-mesh 75 OLSR Link state, example Messages which declare the links state» Topology Control Messages

76 WNP-MPR-mip-mesh 76 The IEEE mesh networks How will the s Mesh Network work?

77 WNP-MPR-mip-mesh 77 Note: This set of slides reflects the view of a s draft standard.

78 IEEE s - Main WNP-MPR-mip-mesh 78 Characteristics Network topology and discovery Inter-working Path Selection and Forwarding MAC Enhancements

79 Elements of a WLAN Mesh WNP-MPR-mip-mesh 79 Network MP - Mesh Point establishes links with neighbor MPs MAP - Mesh AP MP + AP MPP - Mesh Portal STA station standard STA Mesh Portal STA MAP MP MAP MP Bridge or Router STA

80 L2 Mesh Network - Emulates WNP-MPR-mip-mesh LAN Segment Broadcast LAN Unicast delivery Broadcast delivery Multicast delivery LAN Support for connecting an s mesh to an 802.1D bridged LAN Broadcast LAN (transparent forwarding) Learning bridge Support for bridge-to-bridge communications: Mesh Portal participates in STP

81 WNP-MPR-mip-mesh 81 To think about Suppose A sends a frame to B (MAC layer). What MAC addresses are required for the frame transmitted between the two Ethernet switches? And what MAC addresses are required for the frame transmitted between the two MAPs? Why are the 2 cases different? I) A ethernet switch ethernet switch B II) A ))) ))) ))) MAP MAP B

82 WNP-MPR-mip-mesh 82 Mesh Data Frames Data frames» based on frames - 4 MAC address format» extended with: e QoS header, and new Mesh Control header field Frame Control Dur Addr 1 Addr 2 Addr 3 Seq Control Addr 4 QoS Control Mesh Control Body FCS MAC Header Mesh Control Field» TTL eliminates possibility of infinite loops (recall these are mesh networks!)» Mesh E2E Seq Mesh TTL Mesh E2E Seq Mesh Control

83 WNP-MPR-mip-mesh 83 Topology Formation Mesh Point discovers candidate neighbors» based on beacons, which contain mesh information WLAN Mesh capabilities Mesh ID Membership in a WLAN Mesh Network» determined by (secure) association with neighbors

84 WNP-MPR-mip-mesh 84 Mesh Association 1. MP X discovers Mesh mesh-a with profile (link state, ) MeshID: mesh-a Mesh Profile: (link state, ) 2. MP X associates / authenticates with neighbors in the mesh, since it can support the Profile MP X begins participating in 4 link state path selection and 1 data forwarding protocol X Capabilities: Path Selection: distance vector, link state 2 One active protocol in one mesh but alternative protocols in different meshes

85 WNP-MPR-mip-mesh 85 Interworking - Packet Forwarding Destination inside or outside the Mesh? outside inside Portal forwards the message Use path to the destination

86 Hybrid Wireless Mesh Protocol WNP-MPR-mip-mesh 86 (HWMP) Combines» on-demand route discovery based on AODV» proactive routing to a mesh portal distance vector routing tree built and maintained rooted at the Portal

87 No Root, Destination Inside WNP-MPR-mip-mesh the 87 Mesh Communication: MP4 MP9 MP4 1 X checks its forwarding table for an entry to MP If no entry exists, MP4 sends a broadcast RREQ to discover the best path to MP MP9 replies with unicast RREP Data communication begins On-demand path

88 No Root, Destination Outside WNP-MPR-mip-mesh the 88 Mesh Communication: MP4 X MP4» first checks its forwarding table for an entry to X» If no entry exists, MP4 sends a broadcast RREQ to discover the best path to X» When no RREP received, MP4 assumes X is outside the mesh and sends messages destined to X to Mesh Portals X 9 10 Mesh Portal that knows X may respond with a unicast RREP 8 On-demand path

89 HWMP Example 2: WNP-MPR-mip-mesh 89 Root, Destination Inside the Mesh Communication: MP 4 MP 9 Root X MPs learn Root MP1 through Root Announcement messages MP 4 checks its forwarding table for an entry to MP If no entry exists, MP4 forwards message on the proactive path to Root MP When MP1 receives the message, it forwards on the proactive path to MP9 8 MP9, receiving the message, may issue a RREQ back to MP 4 to establish a path that is more efficient than the path via Root MP1 Proactive path On-demand path

90 HWMP Example 4: WNP-MPR-mip-mesh 90 Root, Destination Outside the Mesh Communication: MP4 X MPs learn Root MP1 through Root Announcement messages Root X If MP4 has no entry for X in its forwarding table, MP 4 may forward the message on the proactive path toward the Root MP1 When MP1 receives the message, if it does not have an active forwarding entry to X it may assume the destination is outside the mesh Mesh Portal MP1 forwards messages to other LAN segments Proactive path

91 WNP-MPR-mip-mesh 91 Radio Aware OLSR (RA-OLSR) OLSR may be used in alternative to AODV RA-OLSR proactively maintains link-state for routing

92 WNP-MPR-mip-mesh 92 MAC Enhancements for Mesh Intra-mesh Congestion Control Common Channel Framework (Optional)

93 WNP-MPR-mip-mesh 93 Need for Congestion Control Mesh characteristics» Heterogeneous link capacities along the path of a flow» Traffic aggregation: Multi-hop flows sharing intermediate links Issues with the MAC for mesh» Nodes blindly transmit as many packets as possible, regardless of how many reach the destination» Results in throughput degradation and performance inefficiency High capacity link Low capacity link Flow

94 Intra-Mesh Congestion Control WNP-MPR-mip-mesh 94 Mechanisms Local congestion monitoring (informative)» Each node actively monitors local channel utilization» If congestion detected, notifies previous-hop neighbors and/or the neighborhood Congestion control signaling» Congestion Control Request (unicast)» Congestion Control Response (unicast)» Neighborhood Congestion Announcement (broadcast)

95 WNP-MPR-mip-mesh 95 Common Channel Common channel» Unified Channel on which MPs jointly operate MP3» Using RTX, the transmitter suggests a destination channel» Receiver accepts/declines the suggested channel using CTX» The transmitter and receiver switch to the destination channel» Data is transmitted» Then they switch back MP1 MP2 MP4 SIFS DIFS SIFS Switching Delay DIFS SIFS Common Channel RTX CTX RTX CTX SIFS RTX CTX Data Channel n DATA ACK Data Channel m Switching Delay DIFS DATA ACK Switching Delay DIFS SIFS

96 WNP-MPR-mip-mesh 96 Control Frames Request to Switch (RTX) Frame Frame Control Duration/ ID RA TA Destination Channel Info. FCS Clear to Switch (CTX) Frame Frame Control Duration/ ID RA Destination Channel Info. FCS

97 WNP-MPR-mip-mesh 97 Paper to Review FEKRI M. ABDULJALIL AND SHRIKANT K. BODHE, A Survey of Integrating IP Mobility Protocols and Mobile Ad hoc Networks, IEEE Communications Surveys, First Quarter 2007