CMPE 257: Wireless and Mobile Networking

Transcription

1 CMPE 257: Wireless and Mobile Networking Katia Obraczka Computer Engineering UCSC Baskin Engineering Lecture 8 CMPE 257 Spring'15 1

2 Announcements Project proposals. Feedback. Class schedule updated. Exam: May 19 th. Project presentations: June 10 th, 2 5pm. CMPE 257 Spring'15 2

3 Student Presentations Schedule May 21: Sam May 26: Larissa and Armando May 28: Daniel and Alan June 2: Ben and Maziar June 4: Larissa: user mobility and modeling (May 26) Daniel: location management and geocasting (May 28) Ben: service discovery (June 2) Armando: (May 26) Alan: SDN (May 28) Sam: propagation models (May 21) Anuj: IoT (May 26) Maziar: ICN (June 2) CMPE 257 Spring'15 3 CMPE 257 Spring'15 3

4 What is multicast routing? Multicast routing or application-level multicast? CMPE 257 Spring'15 4

5 Network-Supported Multicast As opposed to application-layer multicast. What s the difference? CMPE 257 Spring'15 5

6 CAROM: Context-Aware Routing over Ordered Meshes JJ Garcia-Luna Rolando Menchaca From Rolando s presentation at Infocom 2010 CMPE 257 Spring'15 6

7 Interest-Driven Routing Mesh based. Integrated routing: The same control signaling is used to support unicast and multicast routing. The distinction between on-demand and proactive signaling for routing is eliminated. Interest-driven signaling is used instead. Regions of interest or enclaves. CMPE 257 Spring'15 7

8 Enclaves S D CMPE 257 Spring'15 8

9 Enclave per active destination Enclaves S Confines signaling to regions of interest and limits flooding D A region of interest, or enclave, contains those nodes that are relevant to the flow CMPE 257 Spring'15 9

10 Enclaves: unicast Unicast active destination: at least 1 active source S A new active source forces a set of nodes to join D s enclave D S CMPE 257 Spring'15 10

11 Enclaves: multicast Multicast active destination: at least 1 active source and 1 active member. M M M S M CMPE 257 Spring'15 11

12 Enclaves: multicast M M M S A multicast enclave has to cover all the members of the multicast group M CMPE 257 Spring'15 12

13 RoI or Enclaves Once established, they restrict the scope of signaling. RoI ordered using sequence numbers, hop count, etc. Data routed over mesh containing shortest paths. CMPE 257 Spring'15 13

14 RoI for D: active sources S1 and S2, relays on shortest paths, nodes 1-hop away from shortest paths. RoI CMPE 257 Spring'15 14

15 Mesh Establishment and Maintenance Mesh activation requests (MRs). Flooded till they reach RoI of intended destination. Establish ordering of nodes to route mesh announcements (MAs) back to source. If multicast, MR also triggers core election among multicast group members. Mesh announcements (MAs). Advertise mesh periodically. CMPE 257 Spring'15 15

16 Context-Awareness R A region of interest is composed by possibly many shortest paths S 6 6 CMPE 257 Spring'15 16

17 Context-Awareness But, which one is the best? S 6 R CMPE 257 Spring'15 17

18 Context-Awareness But, which one is the best? S 6 R CMPE 257 Spring'15 18

19 Context-Awareness Use end-to-end context information to compute the cost of the paths! S 6 R CMPE 257 Spring'15 19

20 Context-Awareness But, only consider paths in the region of interest! S 6 R CMPE 257 Spring'15 20

21 Cost Metric A cost metric obtained from context information is collected by each node and disseminated along the regions of interest The cost of using a node to reach a destination is proportional to its degree of local mobility its local contention the length of its data and control queues This cost is also inversely proportional to the number of feasible parents that the node has to reach the intended destination CMPE 257 Spring'15 21

22 Performance Results We present simulation results comparing CAROM against ODMRP for the case of multicast traffic CAROM against AODV and OLSR for the case of unicast traffic, and CAROM against AODV with ODMRP and OLSR with ODMRP for the case of combined unicast and multicast traffic Performance metrics: Packet delivery ratio Generalized group delivery ratio (multicast) End-to-end delay Path-length specific end-to-end delay (unicast) Group end-to-end delay (multicast) Total and control overhead CMPE 257 Spring'15 22

23 Simulation Environment Qualnet nodes in a simulation area of m 2 Combination of Group and Random Waypoint mobility models 1-10m/s and pause time of 10s R.W. 1-10m/s and pause time of 10s Group mobility b at bps MCBR and CBR 1000 pkts per source, 10 packets per second Exponentially distributed flows with variable mean inter arrival time and mean flow duration equal to one third of the total simulation time CMPE 257 Spring'15 23

24 Combined Multicast and Unicast Traffic Delivery Ratio (5 ucast flows) ~25% ~20% >Twice as many CMPE 257 Spring'15 24

25 Combined Multicast and Unicast Traffic E2E Delay (5 ucast flows) one order of magnitude Two orders of magnitude CMPE 257 Spring'15 25

26 Combined Multicast and Unicast Traffic E2E Group Delay one order of magnitude Three orders of magnitude CMPE 257 Spring'15 26

27 Combined Traffic Path-length specific E2E Delay three orders of magnitude CMPE 257 Spring'15 27

28 Combined Multicast and Unicast Traffic Ctrl and Total Overhead (5 ucast flows) ODMRP AODV ODMRP OLSR >Ten times CAROM ~constant 28 CMPE 257 Spring'15

29 Wireless Internetworking CMPE 257 Spring'15 29

30 Wireless Internetworking Extension of Internet services to wireless/mobile users. Challenges? Wireless medium. Node mobility. TCP/IP stack. CMPE 257 Spring'15 30

31 Mobility IP assumes fixed nodes. Hierarchical addresses. IP address = network number+host number. IP address uniquely identifies host s PoA. Host must attach to network specified by its IP address to send/receive datagrams. But what if nodes move? Change address? How about packets destined to them? CMPE 257 Spring'15 31

32 Mobile IP Addresses redirection. Manages mobility at the IP layer. Hides mobility from upper layers. CMPE 257 Spring'15 32

33 Mobile IP: Goals Nodes can receive datagrams no matter where they attach to the Internet. IMHP (Internet Mobile Host Protocol) as Mobile IP precursor. CMPE 257 Spring'15 33

34 Last-hop Mobility Mobile IP is the Internet standard for lasthop mobility support in IP networks (RFC 2290). How do we deliver IP packets when the endpoints move? Mobile host must be able to communicate after changing its link-layer point-of-attachment. Mobile host must be able to communicate using its permanent (home) IP address. CMPE 257 Spring'15 34

35 Mobile IP: Design Issues Issues: Impact on IP addressing. Impact on routing. Impact on higher layers. Key design considerations: Scale. Compatibility. Transparency. CMPE 257 Spring'15 35

36 Terminology Home Agent (HA) Foreign Agent (FA) HN CH Mobile Host (MH) CMPE 257 Spring'15 36

37 Terminology (Cont d) Similar to cellular. Mobile Node (MN or MH): node changing its PoA. Correspondent Host (CH). Home Network (HN) and Foreign Network (FN). CMPE 257 Spring'15 37

38 Terminology (Cont d) Mobility Agents: Home Agent (HA): router on MN s HN that tunnels datagrams to MH when away and keeps MH s current location info. Foreign Agent (FA): router on foreign network; delivers datagrmas to MH while on FN. Home Address (HoA) and Care-of Address (CoA): HoA: MH s permanent address on HN. CoA: MH s temporary address on FN. CMPE 257 Spring'15 38

39 Care of Address FA-based. MN s address is its current FA s address. FN-based. Locally-assigned address in FN. E.g., DHCP address. What s the difference? CMPE 257 Spring'15 39

40 Mobile-IP: Basic Operation MH normally uses its home address HoA. When MH visits a foreign network, Registration with FA. Discover mobile agent and CoA. Registration with HA. Binding update (HoA -> CoA). Communicating with MN: use HoA. HA forwards packet from HoA to CoA. CMPE 257 Spring'15 40

41 Discovering Agents Agents periodically beacon advertisements CMPE 257 Spring'15 41

42 Agent Discovery Agent advertisement (beaconing): Mobile agent broadcast agent advertisement at regular intervals ( I am here ). Agent solicitation: MH can poll ( anyone here? ). Mobile agent responds to poll. CMPE 257 Spring'15 42

43 Discovering Agents MH polls; agent responds. CMPE 257 Spring'15 43

44 Agent Advertisement Follows ICMP router advertisement message. List one or more available care-of addresses. Inform the MN about special features provided by FA. Example: Alternative encapsulation techniques, header compression. CMPE 257 Spring'15 44

45 Registration CMPE 257 Spring'15 45

46 Registering When away, MH registers its CoA with HA (binding update). Binding: (HoA->CoA) Binding has a lifetime. CMPE 257 Spring'15 46

47 Registration Process MH sends a registration request with CoA. HA authenticates request. HA approves or disapproves the request. HA adds necessary information to its routing table. HA sends registration reply back to MH. CMPE 257 Spring'15 47

48 Registration Process (cont d ) In the case of FA-based CoA: FA is involved in registration. FA is also involved in packet forwarding. Encapsulation. Tunneling. CMPE 257 Spring'15 48

49 Tunneling HA tunnels datagrams destined to MN when MN is away. Datagrams sent to MH directly. Or sent to FA which forwards to MN s CoA. Tunnel terminates at MH s CoA (either the MH or the FA). CMPE 257 Spring'15 49

50 Tunneling SRC Tunneled Data Packet HA keeps binding between MH and CoA CMPE 257 Spring'15 50

51 Encapsulation Tunneling requires encapsulation. Sending the original packet (CH->MH) in another packet (HA->CoA). Default encapsulation mechanism: IP-within-IP (tunnel). Tunnel header: new IP header inserted by the tunnel source (home agent). Destination IP: CoA CMPE 257 Spring'15 51

52 Tunneling in Mobile IP CMPE 257 Spring'15 52

53 The Triangle Routing Problem Aka, dogleg routing. MH->CH: direct. CH->MH: CH->HA->MH Inefficient Solution: route optimization. Deliver binding updates directly to CH. CMPE 257 Spring'15 53

54 Route Optimization Binding caches: Nodes can keep caches with CoA for MHs. If node has entry for MH, sends data directly. Otherwise, triangulates with HA. Binding cache entries have TTL. HA, FA, or MH can send binding cache updates to CH. CMPE 257 Spring'15 54

55 Simultaneous Bindings MN can register multiple CoA swith HA. Why? De-registration. Explicit. Implicit. CMPE 257 Spring'15 55

56 Handoffs MH moving among FN. New CoA registered with HA. Previous FA not necessarily notified. Old registration will expire. New data delivered to new CoA. In-flight data? Dropped and retransmitted by upper layers, or FA notified of new CoA; FA forwards data to new CoA. CMPE 257 Spring'15 56

57 Types of Handoffs MN-initiated: Handoff managed by MN. MN measures signal strength to AP. Decides target AP and switchs over. Network-initiated: APs decide when to hand over and to whom. CMPE 257 Spring'15 57

58 Handoff Signaling Forward handoff: Target AP contacts current AP to initiate handoff. Backward handoff: Current AP contacts the target AP. CMPE 257 Spring'15 58

59 Handoff Delay 3 components: Detect need of handoff. Link establishment between MN and new AP. Registration with HA. Pre- and post-registration handoffs: Pre-registration registers MN with HA before handoff. Post-registration: HA registration happens after handoff. CMPE 257 Spring'15 59

60 Authentication Malicious nodes can infiltrate FNs. Mobile IP registration includes authentication info exchange. MH-HA. MH-FA. HA-FA. Protection against replay attacks. Timestamp and nonces. CMPE 257 Spring'15 60

61 Mobility Support in IPv6 Route optimization is default. Fields for specifying both CoA and permanent IP address. No need for encapsulation. CMPE 257 Spring'15 61

62 TCP Performance in Mobile-IP (Choong) Source of overhead: triangle routing. Additional processing at HA and FA. Additional delay due to triangulation. Additional delay due to fragmentation (extra IP header). Handoffs. CMPE 257 Spring'15 62

63 Goal Determine the impact on TCP performance of Combined overhead sources. Individual overhead sources. CMPE 257 Spring'15 63

64 Methodology Several scenarios that compound or isolate overhead sources. Compare performance of between scenario pairs. FTP transfer btween MH and CH. Metric: TCP throughput. CMPE 257 Spring'15 64

65 Summary of Results Dogleg routing as main cause of TCP throughput degradation. Solution: route optimization. Handoff is second. Mobile-IP s inherent delay in re-establish connectivity with new FA. Solutions: Increase frequency of router advertisements. Use link-layer information to trigger handoff. CMPE 257 Spring'15 65