Source specific multicast routing and QoS issues

Laurentiu Barza

• one-to-many multicast model as defined in Source Specific Multicast

• QoS routing issues

• some QoS routing protocols

Outline:

Source Specific multicast model

A datagram sent with source IP address S and destination IP address G in the SSM range is delivered to each host socket thathas specifically requested delivery of datagrams sent by S to G, andonly to those sockets.

IP addresses in the 232.0.0.0 to 232.255.255.255 range are designated as source specific multicast destination addresses and are reserved for use by source specific applications and protocols.

Source Specific multicast terminology

Service model: Internet Standard Source-Specific

Network Abstraction: group channel

Identifier: G S , G

Receiver Operations: join, leave subscribe, unsubscribe

PIM - SS

• sparse mode protocol

• only builds source specific shortest path trees

• uses a subset of standard PIM-SM messages: Hello, Join/Prune

• used for group ranges designated for SSM

• session advertisement tools must advertise a SSM address

• used in a space where is deployed IGMPv3

Source Specific multicast drafts

Source-Specific Multicast for IP - draft-holbrook-ssm-00.txtH. Holbrook, Cisco Systems; B. Cain, Nortel Networks

PIM-SM rules for Support of Single Source MulticastHal Sandick, Brad Cain - Nortel Networks

Source Specific Protocol Independent MulticastN. Bhaskar, I. Kouvelas - Cisco Systems

Deployment of PIM-SO at Sprint S. Bhattacharyya, C. Diot, Sprint ATL; L. Giuliano SprintLink

Issues in designing a QoS routing algorithm (1):

• the type of distribution tree used ?

• static or dynamic computation of multicast distribution tree ?

• centralized or distributed architecture ?

• which states to held in the routers ? soft states or hard states?

Issues in designing a QoS routing algorithm (2):

• which QoS parameters are used to define the constraints ?

• how many QoS parameters used to calculate the distribution tree ?

• consider a QoS unicast routing protocol (QOSPF) or start from RIP or OSPF and choose the appropriate QoS routing path in the multicast protocol ?

• tradeoff between too much precomputation and signaling

Issues in designing a QoS routing algorithm (3):

• tradeoff of the dynamic of multicast routing tree (route changing): too often: instabillity, loss of packets, joining latency seldom: suboptimal routing(network use), path too long

• replicated adaptive streams or layered video streams ?

• bandwidth reservation or periodical checks of the routes ?

• interdomain ?

Multicast QoS routing algorithms

• Kompella

• Carlberg & Crowcroft

• QoSMIC

• RIMQoS

• QMRP

Kompella ’s algorithm

• first, create a complete graph between the source and receivers

• based on Prim’s minimum spanning tree algorithm

• tree grows from the source

• choose a link that minimizes a given selection function

• assume link state info available

Carlberg & Crowcroft ( spanning-join algorithm )

• a new member broadcast join-request messages in its neighbourhood to find on-tree nodes

• the on tree node reply to the new member

• the new member selects the best candidate path

• signifiant communication overhead

QoSMIC:Quality of Service sensitive Multicast Internet protoCol

• two search procedures: local search and tree search

• local search: a spanning-join procedure for a small neighborhood

• tree search: a Manager node sends BID-ORDER messages in the tree to select a subset of on-tree nodes. The selected nodes send BID messages to the new member

• the new member chooses an appropriate path among the two sets of candidate paths

RIMQoS:Receiver Initiated Multicasting with Multiple QoS Constraints

• assumes a preexisting unicast QoS routing protocol that precomputes QoS paths

• a receiver router knows all the state info within its domain so it calculates an optimal route to the source according to a cost function

• the joining router sends a Request message with the complete source route specified in it

QMRP:A QoS-aware Multicast Routing Protocol

• the new member initiate the routing process by sending a Request message to the core. Request message carries the QoS requirements and it checks the resource availability at every intermediate node

• two searching modes are defined: single path mode and multiple path mode

• if an intermediate node does not have resources it triggers the multiple path mode by sending a NACK message back to the previous node. This node sends the Request message toward other directions than the one defined by the unicast routing path.

Work plan:

• Select multicast routing and Qos support architecture for layered video applications. Evaluate.

• Implement the architecture with a video streaming application

References:

QoSMIC: http://www.acm.org/sigcomm/sigcomm98/tp/abs_12.html

INFOCOM 2000:

RIMQoS: http://www.ieee-infocom.org/2000/papers/722.pdf

QMRP: http://www.ieee-infocom.org/2000/papers/413.ps

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