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MQ : An Integrated Mechanism for Multimedia Multicasting
De-Nian Yang, Wanjiun Liao, Member, IEEE, and Yen-Ting Lin
IEEE TRANSACTIONS ON MULTIMEDIAVOL. 3, NO. 1, MARCH 2001
Outline Introduction RSVP with SPM 、 QoSM MQ : Multicast with QoS
Tree Construction Tree Maintenance Tree Pruning Tree Reshaping Loop Free Control QoS Metrics
Performance Evaluation Conclusions
Introduction Multicast :
A packet contains a class D group address in the destination address field of its IP header.
Quality-of-Service (QoS) :A bound on delay 、 jitter 、 loss ratio or bandwidth
Introduction QoS routing :
Determine a feasible path which satisfies the QoS constraint of a data flow (source)
Make efficient use of network resources Resource reservation for QoS :
Sender-oriented Receiver-oriented : RSVP
RSVP (ReSerVation Protocol)
RSVPDaemon
Application
PolicyControl
AdmissionControl
Packet Classifier
Packet Scheduler
Data
RSVP (ReSerVation Protocol)
Sender
Receiver#1 Receiver#2 Receiver#3
Path
Path
PathResv
Resv
Resv
Reservation request merges as
it travels up the multicast tree.
MQ : Tree Construction The sender multicasts Flow_Ad message
through the shortest path delivery tree to all flow recipients.
The receiver sends a Join_Request message back, and it travels upstream only as far as the closest point of the delivery tree where the requested reservation is met, from where a Join_Ack message is returned.
MQ : Tree Construction The breakout router, the router which is
insufficient to meet the requested QoS, uses QoS routing to determine a new feasible path.
If such a path is found, the router forwards the request toward the new path and waits for an acknowledgement; otherwise returns a Join_Fail message.
Upon receiving a Join_Fail message, the router acts as a breakout router, using QoS routing to determine a path.
MQ : Tree Construction This operation repeats until :
An on-tree router located at the joining path has found a path based on QoS routing and has received a Join_Ack from the new path.
All the on-tree routers have failed to find a path, causing the recipient to receive a Join_Fail.
Upon receiving a Join_Ack, the breakout router Forwards the Join_Ack downstream, and Sends a ResvRev (reservation remove) message
upstream in the old path to relinquish resources.
MQ : Tree Construction
Flow_Ad
Flow_Ad
Join_Request(1)
Join_Request(1)
Join_Request(1)
Join_Request(1)
Join_Ack(2)
Join_Ack(2)
Join_Ack(2)
Join_Ack(2)
Join_Ack(2)
Join_Ack(2)
Join_Ack(2) Join_
Request(1)
Join_Request
(1)
ResvRev(3)
MQ : Tree Construction
Join_Request
(1)
Join_Request
(1)
Join_Fail(2)
MQ : Tree Maintenance Flow_Ad : Sent by a source on three
occasions Periodic distribution Whenever there is a change in the source And per request (Flow_Solicit)
Refresh : Sent by a receiver periodically To keep reservation alive (TearDown) To request a change in QoS
MQ : Tree Reshaping 1. Employs QoS routing with the maximum
reserved bandwidth among all the downstream as the QoS metric to determine a feasible path.
2. Sends an Off_Tree_Query to the new path. The hob count field of the message is incremented by one whenever a router is traversed. The on-tree router receives the message and responds with an Off_Tree_Reply of which the hob count field is copied from the Off_Tree_Query when QoS metric satisfied, or set to infinity otherwise.
MQ : Tree Reshaping 3. Sends an On_Tree_Query message which
travels upstream along the multicast tree until reaching an on-tree router with more than one downstream interface, from where an On_Tree_Reply with a copy of the hob count of the On_Tree_Query is returned.
4. Upon receipt of both returned messages, the reshaping router compares the hob count values. Only when the Off_Tree_Reply is smaller will the tree be reshaped by using Join_Request 、 Join_Ack and ResvRev messages.
MQ : Tree Reshaping
On_Tree_Query
On_Tree_Query
Off_Tree_Query
Off_Tree_Reply
On_Tree_Reply
On_Tree_Reply
Join_Request
Join_Ack
ResvRev
ResvRev
MQ : Loop-Free Control
Join_Request
Join_Request
Join_Request
Join_Fail
Join_Fail
Join_Request
Join_Request
Join_Request
Join_Fail
Join_Fail
Join_RequestJoin_Ack
Join_Ack
ResvRev
ResvRevJoin_Ack
ResvRev
ResvRev
MQ : QoS Metrics
100ms
120ms
80ms
40ms
R3Succeed
R4 Fail !!
R1Succeed
R2 Fail!!
1.0 Mbps100ms
1.5 Mbps120ms
(1.5,30)
(1.5,20)
1.5 Mbps70ms
R2Succeed
Simulation Setup For an edge between pairs of nodes
(u,v), the edge probability is given :P(u,v)=β*exp(-d(u,v)/αL), where 0< α,β≦1 and d(u,v) is the Euclidean distance from u to v.
α↑ : (no. of connections of distant nodes)↑
β↑ : (the edge densities)↑ We use (α,β)=(0.2,0.2) here.
Performance Metrics We compare :
1. RSVP with SPM : MOSPF (hob count) 2. RSVP with QoSM : QOSPF (hob count,
bandwidth) 3. MQ : (hob count, bandwidth)
We measure : 1. Blocking Probability 2. Protocol Overhead 3. Resource Utilization
Conclusions Being a truly receiver-initiated, soft
state, and integrated scheme for multicast QoS services, MQ demonstrates 1. lower blocking probability for users to join
the group of interest with requested QoS, 2. much reduced protocol overhead, and 3. more efficient resource utilization, as
compared to traditional approaches.