ECE 544 Protocol Design Project 2016 - PowerPoint Presentation

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ECE 544 Protocol Design Project 2016

Chengyao Wen

Hua Deng

Xiaoyu Duan

Network Architecture & Topology

Service Objectivek-out-of-n multicast (n = 3, k <= n)Multicast message to ‘best k’ destinationsRouting protocol chooses the ‘best’ multicast path

Network Assumptions

Assumptions

Unreliable network with packet loss prob. per link of p

Each end node is attached to only one router

All links have same characteristics (i.e. hop cost 1 and same MTU 1500 bytes)

Network scale

50 – 100 routers and <= 256 hosts

Protocol Concept

Overall Concept

Multicast message to ‘best k out of 3’ destinations

Static IP address allocation.

Control Packet

ACK

Hello

Hello_ACK

Routing_Update (RIP)

Data Packet

Distance Vector

Go-back-N ARQ

Syntax and Semantics

Control PacketsACKType (1 Byte): Packet Type Seq # (1 Byte): Data Packet Sequence NumberSrc (4 Bytes): Source IP AddressDst (4 Bytes): Destination IP Address

Syntax and Sematics

Control PacketHelloType (1 Byte): Packet TypeSrc (4 Bytes): Source IP AddressHello_ACKType (1 Byte): Packet TypeSrc (4 Bytes): Source IP AddressDst (4 Bytes): Destination IP Address

Syntax and Semantics

Control PacketRouting_UpdateType (1 Byte): Packet TypeLen (1 Byte): Packet LengthIP Addr 1 (4 Bytes): Destination IP Address 1Subnet 1 (4 Bytes): Subnet of Dst IP Address 1Next Hop 1 (4 Bytes): Next Hop Address of Route to Addr 1Hop Cnt 1 (1 Bytes): Total Number of Hop Counts to Addr 1

Syntax and Semantics

Data PacketDataType (1 Byte): Packet TypeLen (1 Byte): Packet LengthTTL (1 Byte): Time to Live (Hops #)K (1 Byte): Number of Destinations in the MulticastFlag (3 Bits): Indicate the validation of Dst1 to Dst3Src (4 Bytes): Source IP AddressDst 1 to 3 (12 Bytes): Destination IP Address 1 to 3 Data: Data Payload

Routing table

DestinationCostNext HopD12R1D23R2D33R2

Routing table of a router

Routing Algorithm

For

each router:

Let

# be the total number of valid

dst

addrs

of

pkt

if

(K=1) // the

pkt

is unicast

if

(K = #)

Directly forward the

pkt

to ‘next hop’ of the valid

dst

addr

;

else

Choose the

dst

with smallest cost, invalidate the rest

dst

and

forward to ‘next hop’ of the chosen

dst

;

else if

(K = #)

if

(all “next hop” for the rest valid

dst

are the same)

The router directly forwards the

pkt

to the next hop;

else

The router duplicates

pkt

, invalidates specific

dst

addr

and

changes K value to # and forwards to corresponding

‘next hop’;

Routing Algorithm

else if

(K = 2 and # = 3

)

if

(all ‘next hop’ are same for 3

dst

)

Directly

forward the

pkt

to ‘next hop

’;

else

Router operate ‘best k-

out-of

N’ routing

Split 3

dst

into groups with 2

dst

each

Compute total cost for each group

if

(‘next hop’ is same for

dst

in a group)

totCost

= Cost1 + Cost2 – 1

else

totCost

= Cost1 + Cost2

Choose the group with smallest

totCost

as the ‘best k

’

dst

and

router

invalidate the not chosen

dst

and repeat

the

algorithm

. (

If multiple groups with same

totCost

,

choose

the

group with

the same ‘next hop’)

Example Networks:

Network 1

According to the algorithm

1. R1 operates “ best K out of N” routing;2. totCost(D1, D2)=totCost(D1,D3)=totCost(D2,D3)=2 ;3. R1 chooses D1 and D2 (with the smallest node ID) and invalidates D2, D3 addr for pkt sending to R2 and invalidate D1, D3 addr for pkt sending to R3.4. In R2, R3, K= # = 1, routers just directly forward the pkt to “next hop”.

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Example Networks:

Network 2

There are two situations:

1.The routing table of R1:2.The routing table of R1

DestinationCostNext hopD12R2

DestinationCostNext hopD12R3

Example Networks:

Network 2

In situation 1According to the algorithm

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K out of N

1.

R1 operates

“best

K out

of N” routing;

2.

totCost(D1,D2) = totCost(D1,D3)=5 and totCost(D2,D3)=6-1=5 with the same “next hop” R3. So D2 and D3 are chosen and D1 addr is invalidated.3. In R3 and R5, K=#=2, both routers directly forward the pkt to “next hop”;

Example Networks:

Network 2

In situation 2According to the algorithm

1.In R1, K=2 and #=3 and all 3 dst have same ‘next hop’, R1 directly forwards the pkt to R3;2. R3 operates “best K out of N” routing;3. totCost(D1,D2)=totCost(D1,D3) = 3 and totCost(D2,D3) = 4- 1 = 3 with same “next hop”. So D2 and D3 are chosen and D1 addr is invalidated.4.In R5, K=#=2, R5 directly forwards the pkt to R6.

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K out of N

Summary

Key features

Routers periodically flood hello message

Routers use DV method to build routing table

Our algorithm

values shared links in ‘best k’ choosing

The method is ‘greedy’ and gets local optimal

Performance

Our algorithm chooses the overall optimal route and destinations in the given examples.

Implementation complexity

Routing table and

pkt

information are used to choose ‘best k’ destinations

Only simple addition and comparison are required for routers