Method and apparatus for determining whether an alias is available to uniquely identify an entity in a communications system

• US 5,388,213 A
• Filed: 10/29/1993
• Issued: 02/07/1995
• Est. Priority Date: 06/06/1990
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Oppenheimer, Alan B., Findley, Sean J., Sidhu, Gursharan S.
• Primary Examiner(s): Richardson, Robert L.
• Assistant Examiner(s): Barry, Lance Leonard
• Application Number:
  US08/146,448
• Time in Patent Office: 466 Days
• Field of Search: 340/825.5, 340/825.52, 340/200, 340/325, 395/200, 395/325
• US Class Current: 709/245
• CPC Class Codes: H04L 12/18 for broadcast or conference , e.g. multicast
• CPC Class Codes: H04L 12/4604 LAN interconnection over a backbone network, e.g. Internet, Frame Relay
• CPC Class Codes: H04L 45/745 Address table lookup; Address filtering
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A method and apparatus for determining whether an alias (or entity name) is available for use in a communication system. A transmitting node or entity transmits a first signal including the alias over the communication system. The alias includes a zone name. If the transmitting node receives a reply signal to the first signal, then the alias is not available for use. Otherwise the alias is available for use. The transmitting node transmits the first signal to a first router connected to a first local network of the communication system. The first router forwards a second signal including the entity name from the first signal to other routers in the network until a second router connected to nodes having the zone name in the entity name is located. Each second router translates the second signal into a third signal which includes the alias, and using a first zone multicast address, multicasts the third signal to a first set of nodes. Each node of the first set of nodes determines whether the zone name contained within the alias is equal to a zone identifier for each node of the first set of nodes. Each node having the zone name determines whether the alias contained within the third signal is equal to alias information for the node. If an entity in the first set of nodes has the alias, then the entity transmits a reply signal, which includes its network address, to the transmitting node.

Claims

1. In a communication system for transferring data between a plurality of devices, a method used by a first entity for determining whether an alias is available to uniquely identify said first entity, said first entity being a networkable computer resource, the method comprising the steps of:

A) said first entity broadcasting a first signal to a first local area network, wherein said first entity is directly coupled to said first local network, wherein said first signal includes said alias, said alias including a zone name,

B) a first routing means of said first local area network translating said first signal into a second signal which includes said alias, said first routing means being coupled to at least one second routing means which is directly coupled to at least one second local area network of said communication system,

C) said first routing means forwarding said second signal to said at least one second routing means,

D) said at least one second routing means computing a zone multicast address from said zone name,

E) said at least one second routing means translating said second signal into a third signal which includes said alias and said zone multicast address,

F) if said at least one second local area network includes a first set of nodes having said zone multicast address, then

F1) said at least one second routing means multicasting said third signal over said second network,

F2) if a second entity of said first set of nodes has said alias, then said second entity transmitting a fourth signal to said first entity, said fourth signal including it network address of said second entity,

G) if said first entity receives said fourth signal, then

G1) said first entity entering said network address into a names table in said first entity, said names table associating said network address with said alias, and

G2) said first entity determining that said alias is not available to uniquely identify said first entity; and

H) if said first entity does not receive said fourth signal, said first entity determining that said alias is available to uniquely identify said first entity.

2. The method of claim 1 wherein said networkable computer resource includes a printer.

3. The method of claim 1 wherein said alias further comprises a type and object portion.

4. The method of claim 1 wherein said first signal comprises an identifier uniquely identifying said first signal, said fourth signal including said identifier to associate said fourth signal with said first signal.

5. In a communication system for transferring data between a plurality of devices, an apparatus in a first entity for associating an alias with a network address, said first entity being a networkable computer resource, the apparatus comprising:

a. transmission circuitry directly coupleable to a first local area network of said communication system;

b. reception circuitry coupleable to said first local area network; and

c. association circuitry coupled to said reception circuitry;

wherein said transmission circuitry broadcasts a first signal to said first local area network when said transmission circuitry is coupled to said first local area network, wherein said first signal includes said alias, said alias including a zone name,

wherein a first routing means of said first local area network translates said first signal into a second signal which includes said alias, and forwards said second signal to at least one second routing means,

wherein each at least one second routing means is directly coupled to at least one second local area network of said communication system,

wherein said at least one second routing means computes a zone multicast address from said zone name, translates said second signal into a third signal which includes said alias and said zone multicast address, and multicasts said third signal to a first set of nodes having said zone multicast address,

wherein if a second entity of said first set of nodes has said alias, then said second entity transmits a fourth signal to said first entity, said fourth signal including said network address of said second entity,

wherein if said second entity transmits said fourth signal, then said reception circuitry receives said fourth signal, and

wherein said association circuitry enters said network address into a names table in said first entity if said fourth signal is received, said names table associating said network address with said alias.

6. The apparatus of claim 5 wherein said networkable computer resource includes a printer.

7. The apparatus of claim 6 wherein said transmission circuitry further includes a means for including a type and object portion within said alias.

8. The apparatus of claim 6 wherein said transmission circuitry further includes a means for including a unique identifier in said first signal for uniquely identifying said first signal, wherein said fourth signal includes said unique identifier to associate it with said first signal.

9. In a communication system for transferring data between a plurality of devices, a method used by a first entity for associating an alias with a network address, said first entity being a networkable computer resource, comprising the steps of:

A) determining whether said first entity is directly coupled to a first local area network,

B) if said first entity is directly coupled to a first local area network, then

B1) said first entity broadcasting a first signal to said first local area network, wherein said first signal includes said alias, said alias including a zone name,

B2) a first routing means of said first local area network translating said first signal into a second signal which includes said alias,

B3) determining whether at least one second routing means is directly coupled to at least one second local area network of said communication system,

B4) if at least one second routing means is directly coupled to at least one second local area network of said communication system, then

B4a) said first routing means forwarding said second signal to said at least one second routing means,

B4b) said at least one second routing means computing a zone multicast address from said zone name,

B4c) said at least one second routing means translating said second signal into a third signal which includes said alias and said zone multicast address,

B4d) determining whether a first set of nodes on said second local area network has said zone multicast address.

B4e) if said first set of nodes has said zone multicast address, then

i) said at least one second routing means multicasting said third signal to said first set of nodes having said zone multicast address,

ii) if a second entity of said first set of nodes has said alias, then

said second entity transmitting a fourth signal to said first entity, said fourth signal including said network address of said second entity; and

said first entity receiving said fourth signal, said first entity entering said network address into a names table in said first entity, said names table associating said network address with said alias.

10. The method of claim 9 wherein said networkable computer resource includes a printer.

11. The method of claim 9 wherein said alias further comprises a type and object portion.

12. The method of claim 9 wherein said first signal comprises an identifier for uniquely identifying said first signal, said fourth signal including said identifier to associate said fourth signal with said first signal.

13. In a communication system for transferring data between a plurality of devices, a method used by a networkable printer for determining whether any entity in said communication system has a particular alias, comprising the steps of:

A) determining if said networkable printer is directly coupled to a first local area network of said communication system,

B) if said networkable printer is directly coupled to a first local area network of said communication system, then

B1) Said networkable printer broadcasting a first signal to said first local area network, wherein said first signal includes said particular alias, said particular alias including a zone name,

B2) a first routing means of said first local area network translating said first signal into a second signal which includes said particular alias,

B3) said first routing means forwarding said second signal to at least one second routing means directly coupled to at least one second local area network of said communication system,

B4) said at least one second routing means computing a zone multicast address from said zone name,

B5) said at least one second routing means translating said second signal into a third signal which includes said particular alias and said zone multicast address,

B6) said at least one second routing means multicasting said third signal to a first set of nodes having said zone multicast address,

B7) if an entity of said first set of nodes has said particular alias, then

said entity transmitting a fourth signal to said networkable printer, said fourth signal including said network address of said entity; and

said networkable printer receiving said fourth signal and entering said network address into a names table in said networkable printer, said names table associating said network address with said particular alias.

14. The method of claim 13 wherein said particular alias further comprises a type and object portion.

15. The method of claim 13 wherein said first signal comprises an identifier for uniquely identifying said first signal, said fourth signal including said identifier to associate said fourth signal with said first signal.

16. A method used by a networkable printer for determining whether any entity in a communication system has a particular alias, wherein said networkable printer is directly coupled to a first local area network of said communication system, comprising the steps of:

a. said networkable printer broadcasting a first signal to said first local area network, wherein said first signal includes said particular alias,

b. forwarding and multicasting said first signal by routers to a first set of nodes having a zone multicast address derived from said particular alias,

c. if an entity of said first set of nodes has said particular alias, then

c1) said entity transmitting a second signal to said networkable printer, said second signal including said network address of said entity;

c2) said networkable printer receiving said second signal, and

c3) said networkable printer entering said network address into a names table in said networkable printer, said names table associating said network address with said particular alias.

17. The method of claim 16 wherein said particular alias further comprises a type and object portion.

18. The method of claim 16 wherein said first signal comprises an identifier for uniquely identifying said first signal, said second signal comprising said identifier to associate said second signal with said first signal.

19. In a communication system for transferring data between a plurality of devices, an apparatus in a networkable printer for determining a network address of any entity in said communication system having a particular alias, the apparatus comprising:

a. transmission circuitry directly coupled to a first local area network of said communication system,

b. reception circuitry coupled to said first local area network; and

c. association circuitry coupled to said reception circuitry;

wherein said transmission circuitry broadcasts a first signal to said first local area network of said communication system, wherein said first signal includes said particular alias;

wherein said first signal is forwarded and eventually multicast by routers to a first set of nodes having a zone multicast address derived from said particular alias;

wherein if any entity of said first set of nodes has said particular alias, said any entity transmits a second signal to said networkable printer, said second signal including said network address of said any entity;

wherein said reception circuitry receives said second signal; and

wherein said association circuitry enters said network address into a names table in said networkable printer if said second signal is received, said names table associating said network address with said particular alias.

20. The apparatus of claim 19 wherein said transmission circuitry further includes a means for including a type and object portion within said particular alias.

21. The apparatus of claim 19 wherein said transmission circuitry further includes a means for including a unique identifier in said first signal for uniquely identifying said first signal, wherein said second signal includes said unique identifier to associate it with said first signal.

22. A method used by a networkable computer resource for avoiding alias duplication in a network, said networkable computer resource having at least one alias, said network having a plurality of zones, said networkable computer resource belonging to a first zone of said plurality of zones, the method comprising the steps of:

A) when an entity in said network is performing an alias registration operation, performing the steps of;

A1) determining if a packet multicast over said network in response to said alias registration operation includes a zone multicast address corresponding to said first zone;

A2) if said packet includes a zone multicast address corresponding to a zone other than said first zone, then ignoring said packet;

A3) if said packet includes a zone multicast address corresponding to said first zone, then performing the steps of;

A3a) determining if said packet is a look-up packet which includes a second alias;

A3b) if said packet is a look-up packet which includes said second alias, then performing the steps of;

i) determining if said second alias included in said look-up packet matches said at least one alias;

ii) if said second alias included in said look-up packet matches said at least one alias, then transmitting a response packet over said network, said response signal including a network address uniquely identifying said networkable computer resource;

B) initiating an alias registration operation to determine whether a particular alias is in use by any entity in said first zone before using said particular alias by performing the steps of;

B1) transmitting a broadcast request packet to cause a router in said network to multicast a lookup-packet containing said particular alias;

B2) receiving a lookup response packet from an entity using said particular alias if said particular alias is in use by any entity in said first zone; and

B3) determining that said particular alias in not in use by any entity if no lookup response packet is received.

23. The method of claim 22 wherein said second alias includes one or more alphabetic characters, the method further comprising the step of converting said one or more alphabetic characters to a selected case of either uppercase or lowercase prior to performing said step of determining if said second alias included in said look-up packet matches said at least one alias.

24. The method of claim 22 wherein said step of determining if said packet multicast by said entity in said network over said network includes said zone multicast address corresponding to said first zone includes the step of examining a zone name field of a network binding protocol tuple contained within said packet.

25. The method of claim 22 further comprising the step of maintaining a names table containing alias-to-entity address mappings of all network visible entities in the networkable computer resource, said names table storing said at least one alias.

26. The method of claim 25 wherein said step of determining if said second alias included in said look-up packet matches said at least one alias comprises the steps of:

comparing said second alias to all aliases contained in said names table; and

transmitting said response packet over said network if said second alias matches any alias in said names table.

27. A method used by a networkable computer resource for avoiding alias duplication in a network, said networkable computer resource having a first alias, said network having a plurality of zones, said networkable computer resource belonging to a first zone of said plurality of zones, the method comprising the steps of:

A) determining if a packet multicast by an entity in said network over said network includes a zone multicast address corresponding to said first zone;

B) if said packet includes said zone multicast address corresponding to a zone other than said first zone, then ignoring said packet;

C) if said packet includes said zone multicast address corresponding to said first zone, then performing the steps of;

C1) determining if said packet is a look-up packet which includes a second alias;

C2) if said packet is a look-up packet which includes said second alias, then performing the steps of;

i) determining if said second alias included in said look-up packet matches said first alias;

ii) if said second alias included in said look-up packet matches said first alias, then transmitting a response packet over said network, said response signal including a network address uniquely identifying said networkable computer resource.

28. The method of claim 27 wherein said second alias includes one or more alphabetic characters, the method further comprising the step of converting said one or more alphabetic characters to a selected case of either uppercase or lowercase prior to performing said step of determining if said second alias included in said look-up packet matches said first alias.

29. The method of claim 27 wherein said step of determining if said packet multicast by said entity in said network over said network includes said zone multicast address corresponding to said first zone includes the step of examining a zone name field of a network binding protocol tuple contained within said packet.

30. The method of claim 27 further comprising the step of maintaining a names table containing alias-to-entity address mappings of all network visible entities in the networkable computer resource.

31. The method of claim 30 further comprising the steps of:

comparing said second alias to all aliases contained in said names table; and

transmitting said response packet over said network if said second alias matches any alias in said names table.