doc.: ieee 802.11-05/0386r2 submission bing zhang, et al. may 2005 slide 1 proactive mesh networks...

May 2005

Slide 1

doc.: IEEE 802.11-05/0386r2

Submission Bing Zhang, et al.

Proactive Mesh Networks (ProM)Date: 2005-05-13

Authors:

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Name Company Address Phone E-mail

Bing Zhang National Institute of Information and Communications Technology

3-5 Hikaridai, Seika-cho,

Soraku-gun, Kyoto, Japan +81-774-98-6820 [email protected]

Oyunchimeg Shagdar ATR Adaptive Communication Research Laboratories

2-2-2 Hikaridai, Seika-cho, Soraku-gun, Kyoto, Japan

+81-774-95-1501 [email protected]

Suhua Tang ATR Adaptive Communication Research Laboratories

2-2-2 Hikaridai, Seika-cho, Soraku-gun, Kyoto, Japan


Youiti Kado Oki Electric Industry Co., Ltd. 2-5-7 Honmachi, Chuo-ku, Osaka, Japan


Masanori Nozaki Oki Electric Industry Co., Ltd. 2-5-7 Honmachi, Chuo-ku, Osaka, Japan


May 2005

Slide 2

doc.: IEEE 802.11-05/0386r2


Outline

• A proactive layer-2 routing protocol – Accommodating legacy STA associated with Mesh AP

– Topology discovery

– WDS unicast/broadcast

• QoS support– Load balancing mechanism

– Delay based priority control

• Multiple radios with distributed channel assignment

• Conclusion

May 2005

Slide 3

doc.: IEEE 802.11-05/0386r2


Proactive Routing Protocol for Mesh Networks

May 2005

Slide 4

doc.: IEEE 802.11-05/0386r2


Architecture - Network Model -

Router

Server Mesh Portal

Mesh AP

Mesh AP

Mesh AP

Legacy STA

・・・ 802.11a(5.2GHz)

・・・ 802.11b/g(2.4GHz)

・・・ 802.11a(5.2GHz)

• Connecting Mesh Points based on proactive protocol

• Efficiently accommodating Legacy STA associated with Mesh AP

MP: Mesh Point

Legacy STA

MP

May 2005

Slide 5

doc.: IEEE 802.11-05/0386r2


Local Topology Discovery- Hello Message Exchange -

• Periodically exchanging Hello message – Advertising 1-hop neighbor information

• Upon receiving the Hello message from neighbors– Checking the link status with 1-hop neighbors

– Acquiring the 2-hop neighbor information

MP-A adds MP list from MP-B that is not included in its 1-hop MP list, into 2-hop MP list.

MP-A MP-B

DAMAC:FF

SAMAC:A

FC Du FCS1-hop Neighbor

MAC Address list

DAMAC:FF

SAMAC:B

FC Du FCS1-hop Neighbor MAC Address list

MP-B adds MP list from MP-A that is not included in its 1-hop MP list, into 2-hop MP list.

Hello frame from MP-A

Hello frame from MP-B

FC Du FCSRA DataTA SADA

WDS Frame RA: Receiver AddressTA: Transmitter AddressDA: Destination AddressSA: Source Address

May 2005

Slide 6

doc.: IEEE 802.11-05/0386r2


Local Topology Discovery- MPR Selection -

• MP determines the OLSR-based MPR (Multipoint Relay) set from its 1-hop neighbors.

• MP advertises its MPR information in the periodic HELLO messages.

MP-A

1-hop neighbor

MPR of MP-A

2-hop neighbor

May 2005

Slide 7

doc.: IEEE 802.11-05/0386r2


Topology Discovery - ASAT & TC Messages -

• Mesh AP generates an ASAT (Associated Station Address Table) message which records a MAC address table of legacy STA associated with it.

• MP generates a TC (Topology Control) message which includes the links to all MPs of its MPR selector set.

ASAT

Leagacy STAs

ASAT

Leagacy STAs

Mesh AP-A Mesh AP-C

MP-B

TC TC

May 2005

Slide 8

doc.: IEEE 802.11-05/0386r2


Topology Discovery- ASAT & TC Message Forwarding -

• MPR forwards the ASAT & TC messages from its MPR selectors.

• Flooding ASAT & TC messages in the network to construct the routes to all of MPs and legacy STAs

MP-ADA

MAC:FFSA

MAC:AFC Du FCS

MP-CDA

MAC:FFSA

MAC:BFC Du FCS

MP-A broadcasts the TC frames(1) MP-B retransmitted the TC frame by replacing SA with MAC:B

(2)

advertised link set

advertised link set

TC frame from MP-A TC frame from MP-B

Mesh AP-A MP-B

(MPR)DA

MAC:FFSA

MAC:AFC Du FCS

ASATSN, MAC:A

MP-C

DAMAC:FF

SAMAC:B

FC Du FCSASAT

SN, MAC:A

ASAT frame from Mesh AP-A ASAT frame from Mesh MP-B

Mesh AP-A broadcasts the ASAT frames

(1) MP-B retransmitted the ASAT frame by replacing SA with MAC:B

(2)

MP-B(MPR)

May 2005

Slide 9

doc.: IEEE 802.11-05/0386r2


Example of Unicast Routing1. STA1 sends a data frame of infra-mode to Mesh-AP1.

2. Mesh-AP1

– learn STA2’s association to Mesh-AP3 from its ASAT.

– transform STA1’s data frame into a WDS frame. – send the WDS frame to Mesh-AP2. (RA : Mesh-AP2, TA : Mesh-AP1, SA : STA1, DA : STA2)

3. Mesh-AP2

– learn STA2’s association to Mesh-AP3 from its ASAT.– forward the WDS frame to Mesh-AP3.(RA : Mesh-AP3, TA : Mesh-AP2, SA : STA1, DA : STA2)

4. Mesh-AP3

– de-transform the WDS frame into the data frame of infra-mode.

– forward the data frame to STA2.

STA1

Mesh-AP1 Mesh-AP2 Mesh-AP3

STA2

(1)

(2) (3)

(4)

May 2005

Slide 10

doc.: IEEE 802.11-05/0386r2


Example of Broadcast Routing

STA1

Mesh-AP1 Mesh-AP2 Mesh-AP3

STA4

(1)

(2) (3)

(4)

STA2 STA3

(2) (4)

1. STA1 sends a data frame to Mesh-AP1. (DA : broadcast address)

2. Mesh-AP1

– transform STA1’s data frame into a WDS frame.

– broadcast the WDS frame to Mesh-APs. (RA : broadcast address, TA : Mesh-AP1, SA : STA1, DA : broadcast address)

– broadcast the data frame to the associated STAs.

3. MPR Mesh-APs broadcast the WDS frame.(RA : broadcast address, TA : own address, SA : STA1, DA : broadcast address)

4. Mesh-APs

– de-transform the WDS frame into the original data frame.

– broadcast to the associated STAs.

May 2005

Slide 11

doc.: IEEE 802.11-05/0386r2


• Supporting multi-path routing for load balancing

– Every flow tends to choose the same minimum hop route. As a result, some MPs are heavily loaded.

– Introducing a flow based multi-path routing to distribute the traffic over the whole networks.

• Supporting delay based priority control

– Many applications (Voice, Video, etc.) are delay sensitive.

– Introducing an end-to-end delay based priority control scheme to reduce the Maximum delay for real time traffics.

QoS Support

May 2005

Slide 12

doc.: IEEE 802.11-05/0386r2


Load Balancing - Problem Specification -

• Why load balancing using multiple paths is required– MPs usually use only a path to each destination.– Traffics to the same destination run down into a single path.– It is desirable to balance the load using multiple paths.

13

2

7

5

0

4 6p2

p1

8

9

heavy Path Index

DA RA

p1 7 3

p2 7 4

Routing Table with Multiple Paths

May 2005

Slide 13

doc.: IEEE 802.11-05/0386r2


Load Balancing- Related Schemes -

• Existing Scheduling Schemes

– MPs randomly select an RA (= next-hop MP) for each packet destined to the same DA.

13

2

7

5

0

4 6

8

9

Path Index

DA RA

p1 7 3

p2 7 4

Routing Table with Multiple Paths

• Merit

– Easy to implement.

• Demerit

– It causes out-of-order frame delivery.

May 2005

Slide 14

doc.: IEEE 802.11-05/0386r2


Load Balancing - Pseudo Flow Based Scheme -

• Pseudo flow : – Type 1 : Identified by DA and SA– Type 2 : Identified by DA and TA (= previous-hop MP)

• MPs generate a pseudo flow table.• MPs determine next-hop MP for each pseudo flow based on the current

load condition.

13

2

7

5

0

4 6f2

f1f1

f2

8

9

Flow Index

DA SA RA

f1 7 8 3

f2 7 9 4

Pseudo Flow Table [type 1]

Flow Index

DA TA RA

f1 7 1 3

f2 7 2 4

Pseudo Flow Table [type 2]

• Merits– Utilizing WDS

header Info.– A pseudo

flow’s path is stable.

– In-order frame delivery.

• Demerit– Cross grained.

May 2005

Slide 15

doc.: IEEE 802.11-05/0386r2


Delay Based Priority Control - Problem Specification -

• Existing QoS schemes :

the same traffic class (ex. Voice)

= the same priority

• End-to-end delay increases with number of hops, congestion and so on!

Delay based priority control scheme should be considered!

1

4

6

5

3

2

Small number of hops:Allowed delay: 50ms; Actual delay: 20ms

• Small number of hops: packets reach their destinations with time to spare

• Large number of hops: packet might not be able to meet the delay requirement

• Small number of hops: packets reach their destinations with time to spare

• Large number of hops: packet might not be able to meet the delay requirement Large number of hops :

Allowed delay: 50ms Actual delay: 80ms

1 6 , Allowed delay: 50ms

2 3 , Allowed delay: 50ms

May 2005

Slide 16

doc.: IEEE 802.11-05/0386r2


• Intermediate nodes dynamically prioritize packets based on their delay requirement and the actual delay characteristics.

• the same traffic class 　　 the same delay requirement

• the actual delay varies with the number of hops and congestion.

• Prioritizing mechanism based on – number of hops

– time stamp

– congestion at intermediate nodes

Delay based Priority Control - Proposed Schemes -

May 2005

Slide 17

doc.: IEEE 802.11-05/0386r2


• Intermediate MPs prioritize packets based on number of hops– Number of hops is learnt from the

routing table.

– Larger number of hops : higher priority

• Forward packets based on their priority level

1

4

6

5

3

2

Routing table

Dest Number of hops

3 1

6 3

Delay based Priority Control - Prioritizing mechanism based on number of hops -

Priority level: higher

Allowed delay: 50ms Actual delay : 40ms

Allowed delay: 50ms Actual delay : 40ms

May 2005

Slide 18

doc.: IEEE 802.11-05/0386r2


Multiple Radios- Distributed Channel Assignment (CA) -

• Premise

– Multiple interfaces/radios, multiple channels

• Basic principle for CA

– Least used channel first

• Features of proposed scheme

– Minimizing co-channel interference

– Auto configuration of the mesh network

– Guarantee connectivity• Both ends of a link share the common channel

IF0

IF1IF1

CB

D

A

May 2005

Slide 19

doc.: IEEE 802.11-05/0386r2


Basic Steps - CA for a Single Link -

• Initiating Mesh-AP(A)S1: Get the common channels (send Request

message)S3: Check CA condition and select the least used

channelS4: Assign the channel to the link (send Reserve

message)S6: Actually set the channel S7: Update channel usage and forward CA message

(GlobalCA)

• Responding Mesh-AP(B)S2: Answer with RequestReply, containing the

available channelsS5: Answer with ReserveReplyS6: Actually set the channel S8: Update CA sequence number and continue CA

A BRequest

Reply

S1S2

GlobalCA over new channel S7

Reserve

Reply

S4S5

ChannelSelection

S3

ChangeChannel

S6ChangeChannel

S6

IF0IF1

IF1

CB

A

D

May 2005

Slide 20

doc.: IEEE 802.11-05/0386r2


Example with Distributed Channel Assignment

After CA

Before CA

wireline network

3 2

1

13 12

7

10

11

96

4

5

8

14

15

16

IF0/ CH0IF1/ CH1

1

3

2

610

1113

4

59

7

814

15

1216

wireline network

3 2

1

13 12

7

10

11

96

4

5

8

14

15

16

C0

C2

C1

C1

C0

C3

C3

C3

C1

C2

C1

C1

C1

C2

C0

C0

C2

C3

C2

1

3

610

1113

12

5

2

47

8

9

14

16

15

Mesh AP1 Mesh AP2

dst, next, hops, ifindex 5 2 2 0 2 2 1 0 4 2 2 0 3 3 1 1 6 3 2 1

Routing Table After CA

interface index = 0channel number = 0neighbor number = 1 neighbor[0] = 2

IF0 Information Table

interface index = 1channel number = 2neighbor number = 1 neighbor[1] = 3


dst, next, hops, ifindex 5 5 1 0 4 4 1 1 1 1 1 0 3 1 2 0 6 5 3 0

Routing Table After CA

interface index = 0channel number = 0neighbor number = 2 neighbor[0] = 5 neighbor[2] = 1


interface index=1channel number = 1neighbor number = 1 neighbor[1] = 4


May 2005

Slide 21

doc.: IEEE 802.11-05/0386r2


CA for Newly Joined Mesh AP

Procedures for New Mesh AP (Mesh-AP-17, 18)

• Mesh-AP-17,18

– monitor the default channel.

– passively scan other channels.

– select the least used channel.

– send Reserve message to the desired neighbor.

• Neighbors respond by sending a Reply.

wireline network

3 2

1

13 12

7

10

11

96

4

5

8

14

15

16

C0

C2

C1

C1

C0

C3

C3

C3

C1

C2

C1

C1

C1

C2

C0

C0

C2

C3

C2

17

18

1

3

6

2

47

17

10

59

8

18

14

15

16 12

13 11

wireline network

3 2

1

13 12

7

10

11

96

4

5

8

14

15

16

C0

C2

C1

C1

C0

C3

C3

C3

C1

C2

C1

C1

C1

C2

C0

C0

C2

C3

C2

17

18

12

3

6

4

5

10

1113

12

9

17

718

814

15

16

Mesh-AP17 and 18 newly joining

After CA

May 2005

Slide 22

doc.: IEEE 802.11-05/0386r2


Conclusions

• A proactive routing protocol – Accommodating the legacy STA associated with Mesh AP

– Optimizing the amount of link-state information

– Supporting unicast and broadcast

• QoS support– Flow based load balancing

• Alleviating out-of-order frame delivery

– Delay based priority control

• Prioritizing mechanism based on number of hops

• Multiple radios

– Assignning the channels with a distributed scheme

doc.: ieee 802.11-05/0386r2 submission bing zhang, et al. may 2005 slide 1 proactive mesh networks...

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