Routing and multicast protocol and algorithm
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路由及群播協定與演算法 Routing and Multicast Protocol and Algorithm. 報告人 : 吳啓鴻. OUTLINE. 何謂路由 靜態路由與動態路由 路由的演算法 網路群組管理協定 IGMP 群播樹 (Multicast Tree) 路徑選擇模式 DVMRP MOSPF PIM-DM PIM-SM CBT. 何謂路由.

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路由及群播協定與演算法 Routing and Multicast Protocol and Algorithm

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Routing and multicast protocol and algorithm

路由及群播協定與演算法Routing and Multicast Protocol and Algorithm

報告人:吳啓鴻


Outline

OUTLINE

  • 何謂路由

  • 靜態路由與動態路由

  • 路由的演算法

  • 網路群組管理協定 IGMP

  • 群播樹(Multicast Tree)

  • 路徑選擇模式

  • DVMRP

  • MOSPF

  • PIM-DM

  • PIM-SM

  • CBT


Routing and multicast protocol and algorithm

何謂路由

  • Internet是由網路與網路之間,以路由器相互連結所建構成的。為了正確的將封包給送到收信的主機,路由器必須將封包傳送到正確的方向才行,而這個要把封包送到「正確的方向」所作的處理,被稱為是選徑、尋徑或是Routing。

  • 路由器會參考路由表格(Routing Table)來進行封包的轉送,將IP位址的Netid,與路由表格裡的Netid比較之後,來決定下一個應送往的路由器。


Routing and multicast protocol and algorithm

靜態路由與動態路由

  • 路由表格與管理的控制表,可分為靜態路由與動態路由這二個種類

  • 靜態路由指的是在路由器或是主機上設定固定的路由資訊的方法。而動態路由的情況,則是使用路由協定,自動設定路由資訊的方法。


Routing and multicast protocol and algorithm

靜態路由與動態路由


Routing and multicast protocol and algorithm

路由的演算法

  • 路徑選擇所使用的演算法有各式各樣,代表性的方法有二個,一個是距離向量型(Distance-Vector) ,另外一個為連結狀態型(Link-State) 。

  • 距離向量型(Distance-Vector)


Routing and multicast protocol and algorithm

路由的演算法

  • 連結狀態型(Link-State)


Routing and multicast protocol and algorithm

IP群播

  • IP位址範圍為 224.0.0.0~239.255.255.255。

  • 除了最高四個位元為1110之外,剩下的二十八個位元是用來表示Group ID。


Routing and multicast protocol and algorithm

網路群組管理協定 IGMP

IGMP(Internet Group Management Protocol)

是讓主機可以加入或離開群組的協定,目前

共有三個版本︰

  • IGMPv1(RFC1112)

  • IGMPv2(RFC2236)

  • IGMPv3(RFC3376)


Igmpv1

IGMPv1

IGMPv1 標頭格式


Multicast tree

群播樹(Multicast Tree)

  • 群播協定使用兩種樹結構做群播

    • 來源基礎樹(Source Based Tree)

    • DVMRP

    • MOSPF

    • PIM-DM

    • 群組共享樹(Group Shard tree)

    • CBT

    • PIM-SM


Source distribution tree

A

B

D

F

Source distribution tree

S

Source

Notation: (S, G)

S = Source

G = Group

C

E

R

R

Receiver 1

Receiver 2


Shared distribution tree

A

B

D

F

Shared distribution tree

S1

Source

Notation: (*, G)

* = all sources

G = Group

Shared Root

S2

C

E

R

R

Receiver 1

Receiver 2


Protocol types

Protocol types

  • Dense mode protocols

    • assumes dense group membership

    • Source distribution tree DVMRP (Distance Vector Multicast Routing Protocol)

    • MOSPF (Multicast OSPF)

    • PIM-DM (Protocol Independent Multicast, Dense Mode)

  • Sparse mode protocol

    • assumes sparse group membership

    • Shared distribution tree

    • CBT (Core Base Tree)

    • PIM-SM (Protocol Independent Multicast, Sparse Mode)


Dvmrp 1 form a source tree by exchanging metric

DVMRP (1) form a source tree by exchanging metric

source tree

S

Source

DF

R1

Receiver 1


Dvmrp 2 broadcast

DVMRP (2) broadcast

source tree

S

datagram

Source

DF

R1

Receiver 1


Dvmrp 3 prune

DVMRP (3) prune

source tree

S

datagram

Source

IGMP DVMRP-Prune

DF

R1

Receiver 1


Dvmrp 4 x and y pruned

DVMRP (4) X and Y pruned

source tree

S

datagram

Source

DF

X

Y

R1

Receiver 1


Dvmrp 4 new member

DVMRP (4) New member

source tree

S

datagram

Source

IGMP DVMRP-Graft

DF

X

Y

R1

R2

Receiver 1

Receiver 2


Dvmrp 4 new branch

DVMRP (4) New branch

source tree

S

datagram

Source

IGMP DVMRP-Graft

DF

X

Y

R1

R2

Receiver 1

Receiver 2


Mospf

MOSPF

  • MOSPF (Multicast Extensions to OSPF)為 OSPF協定的延伸

  • OSPF為連結狀態的路由協定。在路由器之間,交換網路的連結狀態,作成網路的拓樸資訊。然後,利用這個拓樸資訊為基礎,來作成路由表格


Mospf1

MOSPF

  • 每一個在群播資料路徑上的MOSPF路由器是以傳送儲存器的內容作為它推送判斷的基礎。

  • 推送儲存器項目由兩部分組成:

    • 區域群組資料庫(Local group database)

    • 最短路徑樹(shortest path tree)


Mospf2

MOSPF

  • 連結狀態型的路由協定,在網路變大的情況下,用來表示連結狀態的拓樸資料庫就會變大,而造成路徑選擇資訊的困難。

  • OSPF為了能夠減輕這個計算所造成的負荷,而導入了稱為Area的概念。

  • 所謂的Area,是指將數個網路與數個主機,整合成群組的動作。在每個AS內,可以存在著多數的Area。


Routing and multicast protocol and algorithm

Each subnetwork

consists of a designated

router (DR), which is

responsible for sending

IGMP host membership

queries and listens to the

IGMP host membership reports.


Routing and multicast protocol and algorithm

CBT

  • 核心基礎樹(Core-based tree,CBT) 協定是使用一種群組共享協定,它使用核心做為樹的根。每個區域有一台核心路由器(Core router)

  • 樹的形成

    • 由接收端傳送加入訊息(join message) ,表示要加入一個群組。此訊息經過於送出者與會合點間的所有路由器。

    • 每台在其間的路由器從訊息取出所需的資訊,比如:送出者單點傳送位址、封包到達路由器的介面,然後把訊息前送給下一台路由器。

    • 會合點路由器收到一群組所有成員的加入訊息後,樹就建立起來。

    • 如果一路由器想要離開某一群組,它送出離開訊息,給其上游路由器。然後,上游的路由器移去到這台路由器的路徑


Routing and multicast protocol and algorithm

CBT


Routing and multicast protocol and algorithm

CBT

  • 等樹形成後,任一來源就能夠送出群播封包給群組的所有成員。


Routing and multicast protocol and algorithm

PIM的介紹

  • PIM 是一個架構在底層unicast路由協定上的群播路由協定。PIM-SM和其它協定最大的不同在於其採用明確加入模式(explicit join model)。群組成員首先加入一棵share tree而且可以依照需求將此樹切換成以特定發送端為root的最短路徑樹(shortest path tree, SPT),如此可達到更有效率的群播傳輸。


Dense mode vs sparse mode

Dense-mode vs Sparse-mode

  • Dense-mode(密集模式)

    • 適合經常有request 需求

    • 設定簡單

    • 適合 LAN

  • Sparse-mode(稀疏模式

    • 適合少量需求

    • 設定較複雜

    • 適合 WAN


Pim dm 1 initial flood of data

PIM-DM(1)Initial flood of data

S

Source

A

B

G

F

C

D

H

I

E

R1

R2

Receiver 1

Receiver 2


Pim dm 2 c and d assert to determine forwarder for the lan c wins

PIM-DM(2)C and D Assert to DetermineForwarder for the LAN, C Wins

S

IGMP PIM-Assertwith its own IP address

Source

A

B

G

F

C

D

H

I

E

R1

R2

Receiver 1

Receiver 2


Pim dm 3 i e g send prune h send join to override g s prune

PIM-DM(3)I, E, G send PruneH send Join to override G’s Prune

S

IGMP PIM-Prune

Source

IGMP PIM-Join

A

B

G

F

C

D

H

I

E

R1

R2

Receiver 1

Receiver 2


Pim dm 4 i gets pruned e s prune is ignored since r1 is a receiver

PIM-DM(4)I Gets PrunedE’s Prune is Ignored (since R1 is a receiver)

S

Source

A

B

G

F

C

D

H

I

E

R1

R2

Receiver 1

Receiver 2


Pim dm 5 new receiver i send graft

PIM-DM(5)New Receiver, I send Graft

S

IGMP PIM-Graft

Source

A

B

G

F

C

D

H

I

E

R1

R2

Receiver 1

R3

Receiver 2

Receiver 3


Pim dm 6 new branch

PIM-DM(6)new branch

S

IGMP PIM-Graft

Source

A

B

G

F

C

D

H

I

E

R1

R2

Receiver 1

R3

Receiver 2

Receiver 3


Pim sm

PIM-SM

Receiver R1

Source

RP

A

B

C

D


Pim sm1

PIM-SM

Receiver R1

Source

Register

RP

A

B

C

D

Source begins sending

A encapsulates data in register

messang and unicasts it to the

RP.

R1 begins receiving data


Pim sm2

PIM-SM

Receiver R1

Source

Register Stop

RP

A

B

Join

C

D

RP sends joins toward the source

when it starts receiving data on

the source tree, a register stop

is sent to A.


Pim sm3

PIM-SM

Receiver R1

Source

RP

A

B

Join

C

Join

D

Receiver R2 joins group

D sends join towards RP

C sends join towards RP

R2 receives data on RP tree

Receiver R2


Pim sm4

PIM-SM

Receiver R1

Source

RP

A

B

C

(S,G)RP prune

D

(S,G) Join

D sends (S,G) join towards source

A begins forwarding. SPT tree exists

D sends (S,G) RP Bit prune towards RP

Receiver R2


Pim sm5

PIM-SM

Receiver R1

Source

RP

A

B

C

D

R2 is receiving data on source tree,

R1 is receiving data on shared (RP) tree

Receiver R2


Pim sm6

PIM-SM

Source

RP

A

B

C

D

R1 sends IGMP leave

RP stops forwarding on R1 LAN

RP sends (S,G) prune towards source

Receiver R2


Multicast in wireless mobile environments

Multicast In Wireless Mobile Environments


Introduction

Introduction

  • Wireless Network Categories

  • Introduce the issues involved in providing multicast in a mobile environment

  • Discuss details of proposed multicast routing protocols


Wireless network categories

Wireless Network Categories

  • Infrastructure Wireless:

    base station network is connected to the wired Internet.

  • Ad hoc Wireless:

    wireless nodes communicate directly with one another.


Wireless lans

Wireless LANs

(b)Ad hoc Wireless

(a)Infrastructure Wireless


Issues in mobile environments

Issues In Mobile Environments

  • Multicast Forwarding Algorithm

  • A source-based protocol like DVMRP ,DVMRP forwards multicast packets only if it receives them on the correct interface

  • when mobile host (MH) moves to a new domain , its interface to the multicast router changes , resulting in the packets being dropped


Issues in mobile environments1

Issues In Mobile Environments

  • Dense or Sparse Model Protocol

  • The dense mode protocols are useful if there are a lot of users and bandwidth availabilitiy is not a problem, whereas sparse mode protocols are meant for widely distributed users with limited bandwidth.


Issues in mobile environments2

Issues In Mobile Environments

  • Qos Provisioning

  • Quality of service (QoS)-based wireless multicasting is an open issue

  • In this section we first describe Mobile-IP based multicasting protocols


Proposals for multicast over mip

Proposals for Multicast over MIP

  • Remote Subscription

  • It is the simplest way of providing multicast through Mobile IP.

  • In remote subscription an MH re-subscribe to the multicast group each time it moves to a new foreign network.


Remote subscription

Remote Subscription


Out of synch problem

Out-of-synch problem


Compare

Compare


Proposals for multicast over mip1

Proposals for Multicast over MIP

  • Bidirectional Tunneling

  • In this scheme MHs send and receive multicast packets by way of their home agents (HAs), using unicast Mobile IP tunnels from their HAs.


Bidirectional tunneling

Bidirectional Tunneling


Tunnel convergence

Tunnel convergence


Compare1

Compare


Multicast support using mobile ip

Multicast support using Mobile IP

  • Multicast support using Mobile IP (MoM)

  • MoM is based on bidirectional tunneling

  • MoM selected HA among the given set of HA is called designated multicast service provider (DMSP)


Routing and multicast protocol and algorithm

MoM


Dmsp select

DMSP select

  • Classify

  • 1.Agent based

  • 2.Count-based

  • 3.Proximity-based

  • 4.Random-based


Compare2

Compare


Rbmom

RBMoM

  • Range-Based Mobile Multicast (RBMoM)

  • RBMoM provides a trade-off between the shortest delivery path and the frequency of multicast tree reconfiguration

  • It selects a router called a multicast HA(MHA)

  • Every MH can have only one MHA

  • MHA(Multicast HA) is responsible for tunneling multicast data to foreign networks


Select the new mha

Select the new MHA


Compare3

Compare


Proposals for multicast over mip2

Proposals for Multicast over MIP

  • Multicast for Mobility Protocols (MMP)

  • MMP uses a sparse mode multicast routing protocol Core Base Trees (CBT) to handle the movement of mobile nodes within a foreign network.

  • This scheme uses a shared-tree, to and from a centre point called the core of the network.

  • MMP relies on Mobile IP Agent Discovery procedure in order for mobile hosts to discover relevant Mobility Agents and obtain a multicast care-of-address.


Routing and multicast protocol and algorithm

MMP

1.BS transmit periodic beacons with Agent Advertisement messages

2.MN transmits a Registration Request to the base station

3.BS will send a Join request to the Core and create a permanent group

4.MN moves to another cell, it will initiate handoff when it receives a stronger beacon


Mobicast

MobiCast

  • MobiCast is designed for an internetwork environment with small wireless cells, with many cells grouped together and served by domain FAs (DFAs).


Mobicast1

Y

Y

Y

4.X-> DFA-> Y-> all AP

MobiCast

WHEN MN JOIN GLOUP X

1.MN send IGMP message to DFA

2.DFA replace MN join X

3. Construct multicast group Y and all APs join group Y


Reliable wireless multicast protocols

Reliable Wireless Multicast Protocols

  • Reliable Multicast Data Distribution Protocol (RMDP):

    • Uses Forward Error Correction (FEC) and Automatic Retransmission reQuest (ARQ) information to provide reliable transfer. Redundant information is inserted into the FEC, often enabling a receiver to reconstruct the original packet.

    • In the event that such information is not enough, an ARQ is sent to the multicast source which in turn, multicasts the requested packet to all receivers.


Reliable wireless multicast protocols1

Reliable Wireless Multicast Protocols

  • RM2

  • RM2 is a reliable multicast protocol that can be used for both wired and wireless environments.

  • RM2 is a hierarchical protocol that divides a multicast tree into subtrees where subcasting within these smaller regions is applied using a tree of retransmission servers (RSs)


Reliable wireless multicast protocols2

Reliable Wireless Multicast Protocols

  • RS having a retransmission subcast address shared by its members and which may be dynamically configured using the IETF’s Multicast Address Dynamic Client Allocation Protocol (MADCAP).

  • The receivers are required to send negative acknowledgments (NACKs), pointing out the packets to be retransmitted.


Routing and multicast protocol and algorithm

RM2


Compare4

compare


Conclusion

Conclusion

  • This article is an attempt to give an overview of current research in wired and wireless multicast field and show that this area is rapidly growing and evolving.

  • Future directions in wireless multicast need to consider QoS, security, and so on.


Routing and multicast protocol and algorithm

END

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