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Bonjour protocol

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This presentation describes the concept of zero configuration by explaining the bonjour protocol.

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Bonjour protocol

  1. 1. BONJOUR Prepared for Prof. Kaewon Choi By Salah Amean Ahmmed
  2. 2. 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.
  3. 3. 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
  4. 4. 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
  5. 5. 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.
  6. 6. 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
  7. 7. 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
  8. 8. 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.
  11. 11. 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
  12. 12. 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.
  13. 13. 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
  14. 14. 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.
  15. 15. 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.
  16. 16. 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.
  17. 17. 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.
  18. 18. 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
  19. 19. 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
  20. 20. 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
  21. 21. 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
  22. 22. 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
  23. 23. 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.
  24. 24. 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.
  25. 25. 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
  29. 29. ADVERTISING SERVICES  Applications provide a service name and port  follows same DNS specific to general model  ServiceName._ServiceType._TransportProtocolN ame.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
  30. 30. CHALLENGES
  31. 31. SOLUTION  Caching  mDNSresponder takes charge of caching,  Some requests are kept to the time of need  Suppression of duplicate responses  Back-off
  32. 32. CHALLENGES
  33. 33. BONJOUR BONJOUR GATEWAY DEMO  http://www.youtube.com/watch?v=i8vNlqV67uA
  34. 34. DEMO LAB310
  35. 35. REFERENCES  https://developer.apple.com/library/mac/documentation/cocoa/conc eptual/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