Department of Computer Science Southern Illinois University Carbondale QoS and Multicast Routing Pro

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Department of Computer ScienceSouthern Illinois
University Carbondale QoS and Multicast
Routing Protocols for MANETs
Dr. Kemal Akkaya E-mail kemal_at_cs.siu.edu
Some slides are adapted from
UIUC - Louis McCants, Kevan Victor

• Greg Gerou, QoS Routing

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Quality of Service Routing (QoS)

• We mostly have best-effort service in MANETs
• Providing certain performance guarantees (QoS)
  needed
• Real-Time applications
• Multimedia applications
• Bandwidth
• Delay
• Jitter
• Throughput
• Energy
• Internet QoS models
• Differentiated Services DiffServ
• Integrated Services IntServ
• Delay and Bandwidth constrained Routing in MANETs
• Provide certain end-to-end delay or bandwidth
• Minimize delay or bandwidth usage

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QoS routing in MANETs

• Some of the proposed QoS routing protocols
• Core Extraction Distributed AdHoc Routing (CEDAR)
• QOS Extensions to AODV
• Distributed ticket-based QoS routing
• Bandwidth constrained TDMA based routing
• CEDAR
• R. Sivakumar, Prasun Sinha, and V. Bharghavan,
  "CEDAR a Core Extraction Distributed Ad hoc
  Routing algorithm," IEEE Journal on Selected
  Areas in Communications (Special Issue on Ad-hoc
  Routing), vol. 17, no. 8, pp. 1454--1465, Aug.
  1999.
• Key components
• Core extraction
• Link State Propagation
• Route Computation
• Major Goals
• Robust in nature
• Generates admissible Routes on demand
• Core hosts involved computations of routes

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CEDAR

• The core is an approximation of the networks
  minimum dominating set
• Dominating Set Every vertex not in the set is
  adjacent to at least one vertex that is in the
  set.
• Finding an MDS is an NP complete problem.
• Constant time algorithms exist to approximate the
  MDS.

A
G
D
B
C
E
H
F
J
S
K
Node E is the dominator for nodes D, F and K
A core node
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CORE State Info

• Core host have info on
• Local topology of hosts in its domain
• Nearby core hosts
• Maintain virtual links (multi-hop links)
• Core performs all route computations
• Local computation manages core
• Link State Propagation
• Only bandwidth availability of stable links are
  propagated through the core subgraph
• CEDAR is concerned with QoS routing. Bandwidth is
  important
• Propagation is done by slow-moving increase and
  fast moving decrease
• Increase waves indicate bandwidth increases
• Decrease waves indicate bandwidth decreases

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Route Computation

• S ? D
• Core path from dom(S)-gtdom(D) is established
• Core path provides directionality
• Route computation is done on demand
• Possible to apply well known algorithms to the
  core graph
• DSR, TORA, AODV, ZRP, etc.
• CEDAR does it its own way
• The source tells its dominator it wants to send
• Dominator finds a path to the destination
  dominators
• Using a shortest path algorithm

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QoS Routing In CEDAR

• Three Key Components
• 1) Finding the destination and establishing a
  core path to it
• 2) Establishment of a short stable admissible QoS
  route
• 3) Dynamic re-establishment of routes for ongoing
  connections
• QoS route computation is an on-demand routing
  algorithm
• 1) Core Path from dom(s) to dom(d)
• s informs its dom. dom(s)
• dom(s) initiates a core broadcast to set up a
  core path to dom(d)
• a core node u receives the core path request
  message, sets P?P U u then forwards the message
  on its outgoing virtual links
• dom(t) which knows the dom(d) receives the core
  path request message and sends back a source
  rooted unicast core_path_ack message to dom(s)
• dom(t) also sends the inverse path recorded in P
• dom(s) is ready for QoS phase now

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QoS Route Computation

• 2) Finding admissible QoS Route
• dom(s) searches from s to the furthest node in
  core path find in step 1(say t) that can provide
  bandwidth b
• dom(s) picks the shortest widest path from s to
  core node t
• dom(s) sends dom(t) a message containing lt s, d,
  b, P, p(s,t), dom(s), t gt
• b bandwidth, p(s,t) route to t
• dom(t) performs QoS route computation using its
  local state to reach d
• either a path to d is found or the computation
  will fail to compute a path at a core node
• 3) Route Recomputation for ongoing connections
• Required under two circumstances
• The end host moves
• Intermediate link failure
• Mechanisms to correct link failure
• QoS Route Recomputation at the Failure Point
• Node closest to failure point does recomputation
• QoS Route Recomputation at the Source
• Source is notified of failure, then recomputes

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CEDAR - Summary

• Core provides an efficient and low overhead
  infrastructure to perform routing
• CEDAR is robust and only uses local state for
  route computation at core nodes
• CEDAR reacts quickly and effectively to the
  dynamics of a given network
• CEDAR produces good stable admissible routes with
  a high probability
• CEDAR does not require high maintenance overhead
  even for highly dynamic networks
• Disadvantages
• Maintaining CORE
• What if one nodes fails?
• Increase/Decrease waves for bandwidth only
• Could use the same wave idea for other metrics

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Multicast - Introduction

• Multicast ? One to Many
• Class D IP address reserved for multicast
• 224.0.0.0 239.255.255.255
• 224.0.0.0 224.0.0.255 reserved for group
• Multicast groups
• 224.0.0.1 all hosts group
• 224.0.0.2 all routers group
• 224.0.0.4 all DVMRP routers

• Internet Architectures
• Source-based tree
• DVMRP
• MOSPF
• PIM-DM
• Shared tree
• CBT
• PIM-SM

Small to mid-sized networks
Small to large networks
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Multicast Routing Protocols for MANETs

• On-demand Multicast Routing Protocol (ODMRP)
• Sung-Ju Lee, Mario Gerla, and Ching-Chuang Chiang
  " On-Demand Multicast Routing Protocol " , in
  Proceedings of IEEE WCNC'99, New Orleans, LA,
  Sep. 1999.
• Multicast AODV (MAODV)
• Elizabeth Royer and Charles E. Perkins "
  Multicast Operation of the Ad-hoc On-Demand
  Distance Vector Routing Protocol " , Proceedings
  of MobiCom '99, Seattle, WA, August 1999, pp.
  207-218.
• Multicast ZRP (MZR)
• MZR a multicast protocol for mobile ad hoc
  networks Devarapalli, V. Sidhu, D. IEEE
  International Conference on Communications,
  Volume 3, 2001 Page(s) 886 -891 vol.3
• Multicast CEDAR
• P. Sinha, R. Sivakumar and V. Bharghavan,
  "MCEDAR Multicast Core-Extraction Distributed Ad
  hoc Routing", Wireless Communications and
  Networking Conference, 1999, pp.1313-1318

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ODMRP

• Provides a richer connectivity among multicast
  members using a mesh based approach
• Supplies multiple route for one particular
  destination
• Helps in case of topology changes and node
  failure
• Uses a concept of Forwarding Group
• Only a subset of nodes forwards multicast packets
  via scoped flooding

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• Why a mesh?
• Links
• Multicast Routes
• Initial Route from S1 to R2 is lt S1 -A- B- R2gt
• Redundant Route lt S1- A- C- B- R2gt

• On Demand Route and Mesh Creation
• Join Query
• Join Reply
• S floods a Join Query to entire network.
• Join Reply is propagated by each forwarding group
  member until it reaches source via a shortest
  path.
• Routes from sources to receivers builds a mesh of
  nodes called forwarding group
• Maintains Forward Tables
• Provides reliability, redundancy
• ODMRP has a problem of excessive flooding when
  number of multicast senders are more.

R1
S1
A
B
S2
C
R3
S3
R2
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Multicast Operation of AODV

• This operation of MAODV can be explained in three
  steps
• Routing Tables
• Route Discovery
• Multicast Algorithm
• Three routing tables
• Normal routing table
• Multicast routing table
• This table contains entries for multicast groups
  for which it is a router.
• Multicast Group IP Address
• Multicast Group Leader IP Address
• Multicast Group Sequence Number
• Hop Count To Multicast Group Leader
• Next Hops
• Lifetime
• Request Table
• Stores IP address of nodes to join a multicast
  group

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Joining to a Multicast Group
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Multicasting Algorithm

• The first node in a multicast group (MG) will
  act as multicast group leader (MGL).
• Any node can join or leave the MG at any time
  (dynamic in nature)
• Each node must agree to be a router to join the
  group.
• Th dest. addr is the IP address of multicast
  group.
• Th dest. seqno is the seqno of the multicast
  group.
• If the node wishes to join the group it will set
  the J_flag of RREQ and broadcast it
• Otherwise left it blank.
• If source knows the IP address of the group
  leader then it will unicast the RREQ to the MGL

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Route Reply Message Generation

• If a node replies with RREP, it adds two more
  fields to the RREP
• Mgroup_Hop and Group_Leader_Addr.
• Source node will know the number of hops to
  nearest MGL (Mgroup_Hop) and IP address of MGL
  (Group_Leader_Addr).
• Mgroup_Hop will be incremented whenever the RREP
  is forwarded.
• If a source node receives multiple RREPs
• Source node will wait for rte_discovery_timeout
  before it will select the shortest route with
  greatest sequence number.
• Once the source selects the route
• It will send the MACT(Multicast Activation)
  message until the node which initiated the RREP
  is reached.
• In this way MACT will prevent multiple routes.
• MAODV has mechanisms for
• Leaving members
• Link breaks

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Summary - MAODV

• Advantages of MAODV
• Supports unicasting, multicasting and
  broadcasting.
• This is a reactive protocol (on-demand)
• Loop-free Protocol
• Disadvantages of MAODV
• Overhead due to link breakages
• Complex to implement.
• Route Discovery Latency will be High

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Multicast Zone Routing - MZR

• Its a source initiated on-demand multicast
  routing protocol
• Builds a multicast delivery tree rooted at the
  source based on the zone routing protocol
• Does not depend on any underlying unicast
  protocol for global routing substructure
• Multicast Tree Creation
• For each multicast session a tree rooted at the
  source is created.
• The tree is identified by ltsource, groupgt pair
• Multicast route entry consists of
• Multicast session id
• ltsource, groupgt pair
• IP address of upstream node
• A list of the downstream nodes

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Multicast Tree Creation

• Tree Creation is a two step process
• Step 1 Extend tree inside zone
• Source sends a TREE-CREATE to each zone node
• As the TREE-CREATE packet is propagated reverse
  routes are created at each intermediate node
• An interested node replies with a TREE-CREATE-ACK
• The TREE-CREATE-ACK is sent back through the
  reverse route
• As it propagates, the multicast route entry is
  completed and activated

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Multicast Tree Creation

• Step 2 Extend tree to the entire network
• Source sends a TREE-PROPAGATE message to border
  nodes
• On receiving the TREE-PROPAGATE the border node
  does the following things
• Sends a TREE-CREATE packet to all its zone nodes
  and the procedure described in Step 1 is followed
• Once it is done with the zone nodes it sends a
  TREE-PROPAGATE message to its border nodes

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Other details

• Routing Mechanism
• Source starts transmitting once the multicast
  delivery tree is created
• Internal nodes of the tree replicate received
  data packets and send a copy to each node on the
  downstream list
• Transmission to a downstream node is stopped once
  that node migrates
• Maintaining up-to-date routing information
• Timer for each route entry
• Stale route entries removed on time-out
• To keep routes active within multicast session
  source sends TREE-REFRESH packet
• Mechanisms for
• Nodes leaving
• Link breaks