Building-Block ProtocolsBuilding-Block Protocols

Ning YuInformation and Computer Sciences

University of Hawaii at Manoa

Summary

Network Protocols

Building-Block Protocols

Implementation

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By: Edoardo S. Biagioni

To decompose the existing networking protocols into simpler components. It should be possible to easily assemble these components into functional networking protocol stacks. Use of different components or the same components in different orders would lead to different protocols.

Summary

BasicBasic

IdeaIdea

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Network Protocols

The abstract objects that make up the layers of a network system are called protocols.

Definition:Definition:

Host1 Host2

High-level Object

Protocol

High-level Object

Protocol

•Peer-to-peer interface

defines the form and meaning of messages exchanged between protocol peers to implement the communication service.

•Service interface

defines the operations that local objects can perform on the protocol

Protocols generally add headers as the packet moves down the stack in send side, while the

receive side removes the header as the packet moves up the stack.

Protocols generally have two types of functions:

• format functions• control functions

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Building - Block Protocols

lengthlength

countercounter

CRCCRC

de/multiplexingde/multiplexing

checksumchecksum

constantconstant

voidvoid

flow controlflow control

swap

… … et al.et al.

Simply adds a fixed-size

constant header to all outgoing

packets

Removes/ Adds a header for

several higher-level protocol

stacks

Adds a standard CRC

header or trailer

Simply removes a fixed-size

constant header to all outgoing

packets

lengthlength

countercounter

CRCCRC

de/multiplexingde/multiplexing

checksumchecksum

constantconstant

acknowledgementacknowledgement

flow controlflow control

swapswap

… … et al.et al.

Advantages:Advantages:

•Easy assembly of custom protocolsEasy assembly of custom protocols

Advantages:Advantages:

•Easy assembly of custom protocolsEasy assembly of custom protocols

•Explicit interaction between blocksExplicit interaction between blocks

•Easier to write, test and verify

•Explicit interaction between blocksExplicit interaction between blocks

•Easier to write, test and verify

TCPExample

flow control

de/multiplexing

connections

urgent data

acknowledgement

retransmission

bit error detection

fragmentation

resequencing

Assemble Assemblegateway/interface

fragmentation

length

de/multiplexing

routing/loop prevention

Internet addressing

version

bit error detection

type of service

IPExample

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Data Structure

Block’s structure

char * header

int header_size

int (* protocol_function) ( char * spaceBegin, char * dataBegin, char * dataEnd, char * spaceEnd, struct send_protocol_stack * stack);

struct send_protocol_stack * next

send_protocol_stack

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Data Structure

Send stack push

struct send_protocol_stack * send_stack_push( char * header, int header_size, int (* protocol_function)( char * spaceBegin, char * dataBegin, char * dataEnd, char * spaceEnd, struct send_protocol_stack * stack), struct send_protocol_stack * stack);

send _protocol_stack

header_size

header

protocol_function()

next send_protocol_stack

4

send _protocol_stack

header protocol_function() send_protocol_stackheader_size

header

protocol_function()

6send_stack_pushsend_stack_push

header_size6

send_stack_push send_stack_push

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send _protocol_stack

header_size

header

protocol_function()

next send_protocol_stack

4

send _protocol_stack

header_size6header

protocol_function()

send_constant

send_constant

send_constant

send_reorder

send_udp

Data Structure

Send stack push

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Data Structure

receive stack push

receive_check

receive_demux

receive_void

receive_reorder

receive_void

receive_save

receive_reorder

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Implementation

Feasibility

send_constant

send_constant

send_constant

send_gettime

send_udp

receive_void

receive_rtt

receive_void

reflectreflect

receive_udpreceive_udp

send_constant

send_constant

send_constant

send_gettime

send_udp

receive_void

receive_save

receive_void

PingPing--PongPong

Client Server

uhunix2 uhics

Ping-Ponground-trip (us) min/avg/max =3580 /3759/5192

----uhunix2.its.hawaii.edu PING Statistics----round-trip (ms) min/avg/max = 3/3/8

The average Round trip time could be more than 5 ms when more print out

added.

uhunix2 Cleo (Linux)

Ping-Ponground-trip (us) min/avg/max = 2257/3203/10625

--- uhunix2.its.hawaii.edu ping statistics ---round-trip min/avg/max = 3.8/4.8/6.2 ms

Destination Address

48bits

Type

16bits

Source Address

48bits

Ethernet

The Ethernet’s data field carries:

a minimum of 46 byes

a maximum of 1500 bytes

If there are less than 46 bytes of data, the field will be padded to the minimum length

Contains the physical address of the device that is to receive the

packet

Contains the hardware address of the device sending the packet

Indicates the type of management

information present in the packet.

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Simulating Ethernet Header

DestinationIP | port #

48bits

Type

16bits

SourceIP | port #

48bits

Assembly stack

Ethernet Stack

send_extend

send_trim

send_constant

send_constant

send_udp

send_constant

Ethernet send stack

receive_void

receive_demux

receive_void

IP ARP

Ethernet receive stack

ARP

The goal:

To enable each host on a network to built

up a table of mappings between

IP address and link-level addresses

Hardware type

0 16 32

ProtocolType

SourceHardwareAddr

HLEN PLEN Operation

SourceHardwareAddr SourceProtocolAddr

SourceProtocolAddr TargetHardwareAddr

TargetHardwareAddr

TargetProtocolAddr

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Implement ARP reply stack and request stack by using

send_constant

Implement ARP receive stack by using

receive_void receive_check

receive_save receive_switch

ARP stack

Implementation

Internet Protocol (IP)

Version

0 16 32

Length

Ident

TTL Protocol

Offset

SourceAddr

DestinationAddr

HLen TOS

Flags

Checksum

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IP stack Implement IP send stack by using

send_constant send_flag_offset

send_reordersend_counter

Implement IP receive stack by using

receive_demux

receive_reorder

receive_void

receive_flag_offset

Implementation

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A simple implementation of Building-Block Protocol

Stack Structure

Ethernet Stack

ARP Stack

IP Stack

ARP Stack

Ethernet Stack

IP Stack

table_lookup

No Global Variable is used !

Implementation

MAHALO