BONJOUR

Prepared for

Prof. Kaewon Choi

By

Salah Amean Ahmmed

INTRODUCTION

IP like electricity or water Just plug and it work Bonjour is truly revolutionary, it is one of the things that is going to have

the largest impact on application designing over the next couple of years.

BACKGROUND Bonjour is Apple’s implementation of a suite of

zero-configuration networking protocols. Bonjour is designed to make network

configuration easier for users. For example, Bonjour lets you connect a printer to your

network without the need to assign it a specific IP address or manually enter that address into each computer

With zero-configuration networking, Nearby computers can discover its (printers)

existence and automatically determine the printer’s IP address

They can automatically discover the new address in the future even when changes happen

BACKGROUND

Apps can also leverage Bonjour to automatically detect other instances of the app (or other services) on the network.

For example, two users running an iOS photo sharing app could share photos over Bluetooth personal area network without the

need to manually configure IP addresses on either device

WHY BONJOUR?

The transition from platform-specific protocols(AppleTalk) to IP happened over the past two decades

Currently computers and other network devices all use TCP/IP for communication.

In that transition, however, one piece of functionality was lost

the ability to add devices to a local network and then connect to those devices from computers and other devices on the network, all with little or no configuration.

CONCEPT For IP to work, devices need to be assigned

addresses either manually or dynamically(DHCP). A dynamically assigned address can change, Without Bonjour,

Printers and other devices had to be manually configured with a static address so that computers on the network could reach them.

DNS server has to be configured so that computer users didn’t have to connect to the printer by IP address.

Thus, a seemingly minor task required significant configuration.

Sometimes it isn’t practical to have complicated configuration for minor tasks such as printing a paper

CAPABILITY OF BONJOUR Without wasting people time to get configuration

done, people should be to be able to plug in the printer, plug two laptops together, or look for a file server or game server on the local network

To support this, people need a simple and reliable way to configure and browse for services over IP networks.

User want to discover available services and Choose one from a list, instead of having to know

each service’s name or IP address in advance. It is in everyone’s interest for IP to have this

capability

ZERO CONFIGURATION: AN EXAMPLE In step 1, you open up your laptop in your

neighbor’s house, and the laptop either Obtains an address from DHCP server in the

router or, In the absence of a DHCP server, assigns itself

an available local address In step 2, the network is queried for

available printers so that when you open the Print dialog, your neighbor’s

printer is listed In step 3, you turn on music sharing on your

computer, and your neighbor’s computer sees it and connects.

ZERO CONFIGURATION: AN EXAMPLE

ZERO CONFIGURATION: AN EXAMPLE

WHAT IS ZEROCONF NETWORK?

No external supporting infrastructure No manual configuration No (conventional)DHCP Server No conventional DNS server

Limited Network Scope Not too many users Not too many hosts;

Simply by connecting two laptops using Ethernet cable

THREE LEGS OF BONJOUR

Addressing : address is need to identify host on the network

Naming: using names instead of the IP address

Browsing: we need to discover what is in the network.

ADDRESSING

Self-Assigned Link-Local Addressing Pick random address in 169.254/16 Claim this address by ARP ARP to see if anyone else is using it if someone else is using it, try again ongoing conflict checking

Http://www.zeroconf.org/ One of the important issues regarding this sort of

addressing is that they are meant for local usage only typically a small LAN or a single LAN segment

For example when we print a document from host A to a host B on the local network, then this addressing scheme is sufficient

IPV4 LINK-LOCAL AVAILABILITY Self-Assigned IPv4 Link-local Addressing first appeared in

Mac OS8.5,1998 Windows 98, 1998 Mac OS X 10.0

IPv6 already has link-local addressing This is not to compete with it but to encourage

apps to support IPv6 But low cost devices that has no support for IPv6 Major operating systems supports local link

addressing Hardware manufacturers should implement link-

local addressing on their devices to obtain the full benefit of Bonjour.

ADDRESSING WITH ZEROCONF

Device that supports link-local addressing benefits from this feature automatically.

When your host computer encounters a local network, it finds an unused local address and adopts it.

No action on your part is required.

NAMING

Multicast DNS is the proposed solution to the translation of name-to-address on local networks

Because these DNS queries are sent to a multicast address, no single DNS server with global knowledge is

required to answer the queries. Each service or device can provide its own

DNS capability when it sees a query for its own name,

it provides a DNS response with its own address.

NAMING AND RESPONDER

Responder handles mDNS queries for any network service on the device

This daemon takes charge of interpreting mDNS queries and multicast messages

Automatically advertises the availability of your service

so that any queries for your name are directed to the correct IP address and port number automatically.

NAMING

Uniqueness of names is essential for name-to-address to work properly

Names in bonjour have local significance only Pick desired name in ".local."subdomain Issue Query to see if anyone else is using it if someone is else already using it, pick

another ongoing conflict checking

NAMING EXAMPLE

A printer with the default name XYZ-LaserPrinter.local to Local network.

XYZ-LaserPrinter.local, then XYZ-LaserPrinter-2.local,

XYZ-LaserPrinter-3.local is unused,thus becomes the name

Bonjour renames automatically

BROWSING

“what we want to do?” is to just browse what is inside the network rather just type is in the browser some numbers or names

Long list of attempts allows automatic detection of devices/services on networks

RLP (resource location protocol) SDP (Service discovery protocol) SSDP (Simple service discovery protocol) SDS Service discovery services

DEVICE-CENTRIC VS. SERVICE CENTRIC

In device centric A client queries to the server, and checks

what is available on the server Server responds with list of running

service( HTTP, ftp, etc.) Digging inside the server for some relevant

information Decides what services to use The Response:

May not be exactly what the user needs Cause a lot of unneeded network traffic

DEVICE-CENTRIC VS. SERVICE CENTRIC

In service centric: It makes more sense to query for “What print

services are available?” than “what services are you running” then go

though list of available services In this scheme, a single query produce only

relevant replies Services are not tied to specific IP addresses

or even host names (e.g., load-balancing situation)

Queries are made according to the type of service needed, not the hosts providing them

SERVICE DISCOVERY

Service discovery in Bonjour is accomplished by “browsing.”

An mDNS query is sent out for a given service, type and domain

Any matching services reply with their names

The result is a list of available services to choose from.

BONJOUR SERVICE DISCOVERY

Bonjour takes the service-oriented approach. Queries are made according to the type of service needed, not the hosts providing them.

Applications store service instance names, not addresses, so if the IP address, port number, or even host name has changed, the application can still connect.

User’s browsing experience is made more useful and trouble-free.

SERVICE DISCOVERY ADVANTAGES

Allows applications to find all available instances of a particular type of service and

To maintain a list of named services and port numbers So with changes, effect won’t hurt

SERVICE DISCOVERY EXAMPLE

PUBLISHING A SERVICE

PUBLISHING A SERVICE-CONT’

ADVERTISING SERVICES

Applications provide a service name and port follows same DNS specific to general model ServiceName._ServiceType._TransportProtocol

Name.Domain ServiceName is human readable descriptive

name Maximum of 63byte All characters are allowed

HP officeJet8500._ipp._tcp.local. service name is HP officeJet8500 services type(internet printing protocol) is ipp Transport Protocol is tcp Domain is .local

CHALLENGES

SOLUTION

Caching mDNSresponder takes charge of caching, Some requests are kept to the time of need

Suppression of duplicate responses Back-off

CHALLENGES

BONJOUR BONJOUR GATEWAY DEMO

http://www.youtube.com/watch?v=i8vNlqV67uA

DEMO LAB310

REFERENCES https://developer.apple.com/library/mac/documentation/

cocoa/conceptual/NetServices/Articles/NetServicesArchitecture.html

http://www.zeroconf.org/QDIPv4LL.html http://www.youtube.com/watch?v=pdbTyxYmF84 http://www.ietf.org/rfc/rfc3927.txt http://www.aerohive.com/solutions/technology-behind-

solution/bonjour-gateway http://blogs.enterasys.com/apple-bonjour-devices-in-the-

enterprise-part-1/ http://en.wikipedia.org/wiki/Zero-configuration_networking