WO2002011393A2

WO2002011393A2 - Rarp server-independent gateway

Info

Publication number: WO2002011393A2
Application number: PCT/US2001/023898
Authority: WO
Inventors: Jacob M. Mcguire; Jay Soffian
Original assignee: Loudcloud, Inc.
Priority date: 2000-07-31
Filing date: 2001-07-31
Publication date: 2002-02-07
Also published as: AU2001279091A1; WO2002011393A3

Abstract

The present invention is directed to a system and method of assigning a network address to a client on a network using a plurality of protocols. An address request is translated from a broadcast-based network protocol to an address-based network protocol and an address assignment is translated from an address-based network protocol to a broadcast-based network protocol between a network client and a network server. This system and method, in one embodiment, provide a server-independent gateway between specific protocols, BOOTP, DHCP, and RARP, for providing an IP address to a device on a local network, such as an Ethernet network, for example. Also provided by the present invention is a system for handling requests from devices using multiple network protocols, which includes a network server connected to a network, a network client connected to the network, and a gateway connected to the network server and network client for translating communications between the network server and the network client.

Description

RARP SERVER-INDEPENDENT GATEWAYBETWEENDHCP AND RARP

FIELD OF THE INVENTION

The present invention relates generally to network communication protocols, interfaces between different protocols, and the configuration of network information on a server. Specifically, the present invention relates to adding new clients to a network and providing them with network addresses.

BACKGROUND OF THE INVENTION

Computer networks have become an integral part of everyday life. By way of various computer networks, activities such as data sharing, electronic commerce, multi-media broadcasting and other useful exchanges of data have been enabled. Some of these networks include, for example, local area networks (LAN), wide area networks (WAN), the Internet, and other similar networks that utilize data packets for transferring data from one computer location to another. In transferring data from one location on a network to another, a network data transfer protocol, or communications protocol, and an addressing scheme are necessary. One common protocol, made popular by the advent of the Internet, is the Transmission Control Protocol/Internet Protocol (TCP/IP). This protocol is widely accepted as a standard for communications via the Internet. Addresses are also a necessary element of communications on a network.

For example, the Internet protocol (IP) addressing scheme assigns a logical address to each device in communication with the Internet. An IP address has two portions: a network address portion, and a host address portion. The network address portion identifies a network, within which the device being addressed resides, and the host address portion uniquely identifies the device being addressed within that network. The combination of network address and host address is unique, such that no two devices have the same IP address. These addresses are 32 bits long and are usually written in a decimal notation, such as: A.B.C.D, where the variables A, B, C, and D are each an octet having a numerical value between 0 and 255. IP addresses expressed in this form are used in the source address and destination address fields contained within IP packets, and allow for unique addressing of each data packet to a specific device connected to the Internet. Within the IP packets, the IP addresses are expressed in network-byte communication order. Thus, since the address of a particular device on a network is crucial for correctly transmitting data packets to that device, obtaining a unique address identifier, such as an IP address, is important and must be correctly carried out so that the device on the network can communicate with other devices on the network. Accordingly, various protocols have been devised to assign unique logical network addresses, such as IP addresses for the Internet, to devices contained within a local network. Typically, a computer does not know its network address when booted, and only has information regarding its hardware interface address, such as an Ethernet address. To use a protocol such as the Internet Protocol (IP), the computer must be assigned a unique IP address.

Various address assignment protocols have been devised to assign a logical network address, such as an IP address, based on a particular device's hardware interface address, such as an Ethernet address. Two types of protocols that are commonly used for network address assignment are broadcast-based protocols and address-based protocols. Generally, broadcast-based protocols broadcast a request for network address assignment and then do not further utilize the network address that is assigned for communication with the server. Address-based protocols, on the other hand, broadcast a request for network address assignment and then can continue to use the assigned network address to communicate with the server for transmitting configuration information and other data. One specific type of broadcast-based protocol that is discussed in connection with embodiments of the present invention is the reverse address resolution protocol (RARP). Two specific types of address-based protocols discussed in connection with the present invention are the bootstrap protocol (BOOTP) and the dynamic host configuration protocol (DHCP), which is an evolution of BOOTP.

The reverse address resolution protocol (RARP) is a common address resolution protocol used by some computer systems, such as the Ultrasparc servers of Sun Microsystems, Inc. RARP is a broadcast-based protocol that is used to announce a client to the network and request a network address, and has the advantage of being light-weight, or simple. However, because of this simplicity, RARP does not have as many features as other protocols, such as DHCP. For instance, in a network using RARP, an RARP server must be on the same local network as the requesting client. The dynamic host configuration protocol (DHCP) exhibits more features than those associated with the RARP protocol. For example, DHCP clients may communicate with a DHCP server on a different network. Thus, in a system with multiple clients on different networks, only one DHCP server is needed, whereas in a similar situation using RARP, multiple RARP servers are needed for IP address assignment. This is in part due to the fact that DHCP allows for use of a network gateway or helper, such as a router, for example, and RARP does not.

Additionally, address-based network protocols, such as BOOTP and DHCP allow for dynamic configuration of IP addresses, thereby allowing IP addresses to be allocated on a temporary or permanent basis to the requesting client, as deemed necessary. Allocation of IP addresses on a temporary basis allows the entire network to more efficiently manage available IP addresses. An additional advantage of DHCP is that it provides a mechanism for a requesting client to obtain all of the configuration information required for the client to operate on the network.

It is desirable to provide the advantages of protocols such as BOOTP and DHCP to devices which employ RARP. It is therefore desirable to devise a system in which devices using a broadcast-based network protocol, such as RARP can be used with and enjoy the advantages of devices using an address-based network protocol, such as BOOTP and DHCP.

SUMMARY OF THE PRESENT INVENTION

In accordance with the present invention, these objectives are achieved by a system and method that is capable of operating with both types of protocols, address-based network protocols, such as BOOTP and DHCP, and broadcast- based network protocols, such as RARP, on the same network, and thereby utilize the advantages of both types of protocols and allow communication between devices using both types of protocols. In accordance with one embodiment of the present invention, a system and method of assigning a network address to a client on a network that uses a plurality of protocols is provided. When a request is issued from a network client using a broadcast-based network protocol, a hardware or device address is extracted from the request, and a request is generated using an address-based network protocol incorporating the hardware address previously extracted. The request according to the address-based network protocol is used to select the network address for the network client, and a response to the network client to provide the network address is generated using the broadcast-based network protocol. In accordance with another embodiment of the present invention, a system for handling requests from devices using multiple network protocols is provided. This system has a network server that uses an address-based network protocol, at least one network client connected to the network using a broadcast-based network protocol, and a gateway connected to the network for translating between the network client and network server. The gateway translates requests from the network client using the broadcast-based network protocol into requests using the address-based network protocol for handling by the network server. The gateway also translates responses from the network server into responses using the broadcast-based network protocol for the network client.

Through the use of the present invention various advantages are obtained. For example, network clients using multiple protocols may operate on the same network. Additionally, there is no need for an address assignment server on the network of each requesting client.

Further features of the present invention, and the advantages offered thereby, are explained in greater detail hereinafter with reference to specific embodiments illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a block diagram of a typical network using a reverse address resolution protocol (RARP).

Figure 2 is a flow diagram of the steps associated with the reverse address resolution protocol (RARP).

Figure 3 is a block diagram of a typical network using a dynamic host configuration protocol (DHCP).

Figure 4 is a flow diagram illustrating various steps of dynamic host configuration protocol (DHCP) address resolution. Figure 5 is a block diagram of one embodiment of the present invention. Figure 6 is a block diagram of another embodiment of the present invention.

Figure 7 is a flow diagram illustrating the various steps performed by the system and method of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

To facilitate an understanding of the principles and features of the present invention, it is explained hereinafter with reference to its implementation in an illustrative embodiment. In particular, the invention is described in the context of a local network, such as an Ethernet network, in which a DHCP server assigns IP addresses to BOOTP, DHCP, and RARP clients on the local network for communication with an external network, such as the Internet. It will be appreciated, however, that this is not the only embodiment in which the invention can be implemented. Rather, it can find utility in a variety of computer and network configurations, as will become apparent from an understanding of the principles which underscore the invention.

A typical network, which employs the RARP protocol to assign network addresses, is illustrated in Figure 1. In this network, an RARP server 102 is connected, via a local network 104, to various clients 106, 108, 110. The local network 104 may comprise any of a variety of different types of physical networks. For example, the network 104 may be an Ethernet network or other suitable broadcast-based networks, wherein devices request network address assignment using a broadcast-based network protocol.

Also, optionally the network 104 may be connected to an external network 112 as illustrated by the broken line 114. This external network may be a variety of networks external to the local network 104. For example, the external network 112 may comprise the Internet or portions thereof. A flow diagram illustrating the manner in which the RARP network performs address assignment is shown in Figure 2. First, as shown in step 202, a network client broadcasts a message over the local network containing its physical device address, or its Ethernet address, which is contained on its network interface card (NIC). Additionally, other identifiers suitable for use by devices on a broadcast-based network using a broadcast-based network protocol may be used as physical device addresses. Typically, the message broadcast by the network client may be carried out as part of the client's normal boot process. As shown in step 204, an RARP server looks up the device identifier provided in the broadcast message from the network client in a mapping file. This file may be locally stored on the RARP server, such as the server 102 shown in Figure 1, for example, or in a central server. In the case that the local network 104 is an Ethernet network, the Ethernet address may be located in a file name "/etc/ethers. " This file provides a mapping between each Ethernet address and an available IP address. In step 206, the RARP server finds the network address corresponding to the device identifier of the network client broadcasting the message in step 202. This network addresses may be an IP address used in communication via the Internet, for example. Once the network address has been determined by the RARP server, in step 208, the RARP server responds to the requesting client of step 202, transmitting the logical network address corresponding to its physical device identification.

As shown in step 210, upon receiving the network address from the RARP server, the network client may communicate via the external network 112 using the network address provided. It should be recognized by those skilled in the art that the local network discussed in connection with Figures 1 and 2 may comprise an Ethernet network, or other similar, broadcast-based network. In the case of an Ethernet network, the device identifier associated with a network client comprises an Ethernet address. Additionally, the external network discussed in connection with Figures 1 and 2 may advantageously comprise the Internet, or other similar network. Hence, the network address discussed in connection with Figure 2 may comprise an IP address, for example. However, as will also be appreciated by those skilled in the art, the present invention need not be limited to any of the specific embodiments described wherein the local network is an Ethernet network and the external network is the Internet. Rather, the networks of the present invention may comprise any suitable broadcast-based network and address-based network. Figure 3 is a block diagram of a network that operates in accordance with the DHCP or BOOTP protocols. For the sake of simplicity, only DHCP will be referenced in the following discussion. However, it will be recognized that the illustrative example is equally applicable to BOOTP. As with the RARP network of Figure 1, the DHCP network of Figure 3 comprises a server 302 connected by way of a network 304 to various clients 306, 308, 310. The server 302 is a DHCP server using the DHCP protocol. The network 304 may comprise any suitable local network such as those discussed in connection with the network 104 shown in Figure 1.

In one embodiment of the present invention, the network 304 may optionally be connected to an external network 312, as shown by the broken line 314. This external network 312 may comprise the Internet, or other similar network.

In Figure 4, a flow diagram illustrating the basic steps of address assignment in a DHCP network are shown. In step 402, a client broadcasts a message over the network requesting a network address. This request includes a device identifier for the client, and a session identifier for the client. A decision is made, as illustrated by decision box 404, whether more than one DHCP server is present on the network. If there is more than one DHCP server on the network, as indicated by step 406, a specific DHCP server is chosen to provide a network address to the requesting client. For instance, each server may generate an initial response to the request from the DHCP client. Upon receiving multiple responses, the client can select one of the servers to continue further processing of the request and issue an IP address. If there is not more than one DHCP server on the network, or once a DHCP server has been chosen, at step 408 the DHCP server responds to the client with the network address and configuration information. Figure 5 is a block diagram illustrating one embodiment of a network in which the present invention can be employed. In Figure 5, at least one RARP client 504 is connected to a network 508 in which logical network addresses are assigned by a DHCP server 502. To enable the RARP client 504 to employ the services of the DHCP server, a DHCP proxy 506 operates as a gateway between the RARP client 504 and the DHCP server 502, acting as a translator between the two protocols used by these two respective devices. In this configuration, any network address assignment, such as IP address assignment, for example, is carried out by the DHCP server 502 in response to requests broadcast from the RARP client 504 that are relayed via the DHCP proxy 506. Likewise, any transmissions of such address information from the DHCP server 502 is communicated to the RARP client 504 by way of a DHCP proxy 506. For the sake of illustration, the DHCP server and the DHCP proxy are depicted as separate logical devices on the network. It will be appreciated, however, that they can be embodied in the same physical device. In addition, the proxy 506 may use address-based protocols other than DHCP, such as BOOTP, and the like.

In Figure 6, a second embodiment of a network which employs the present invention is shown, wherein a DHCP server 602 is located on one network 604, and an RARP client 606 and an RARP-to-DHCP proxy 607 are contained on another network 608. In this embodiment, a DHCP helper 610 is used for mediating requests and data transmissions between the DHCP server 602 and the RARP client 606, as relayed by the RARP-to-DHCP proxy 607. This DHCP helper 610 may be, for example, a network router that interconnects the two local networks. In an embodiment of the present invention, the proxy 607 is used to assist the DHCP helper 610 in converting RARP requests to DHCP requests. For instance, the DHCP helper 610 may be a router, which has no method of internally storing data, such as a hard drive or the like. In such a case, the proxy 607 may be used to provide such functionality. However, if the DHCP helper 610 resides on a router with storage capabilities, the present invention may employ an alternative embodiment in which the functionality of the RARP-to-DHCP proxy 607 is actually contained within the DHCP helper 610.

It will be understood by those skilled in the art that the network 604 and network 608 may be individual local area networks, or subnetworks in a larger network, e.g. , a WAN. Similarly, the network 604 may comprise any of a variety of different types of networks, such as Ethernet networks, FDDI networks, token ring networks, asynchronous transfer mode networks (ATM), frame relay networks, cable networks, and the like. The term client, as used in connection with the present invention, may include any computer on a network that relies on the DHCP server 502, 602 to provide a network address. For example, the RARP client 504, 604 could be a file server, such as the Ultrasparc server of Sun Microsystems, or other similar server. Additionally, it will be understood by those skilled in the art that protocols other than RARP and DHCP may be used in the embodiment shown in Figure 6. For example, another address-based network protocol, such as BOOTP, may be used instead of DHCP and another broadcast- based network protocol may be used instead of RARP. Figure 7 is a flow diagram of the method performed by the various embodiments of the present invention, such as those shown in Figures 5 and 6, for example. In step 702 of Figure 7, an RARP client generates a request using a broadcast-based network protocol, such as an RARP request, in the normal manner. In step 704 a DHCP gateway, e.g. , the DHCP client of Figure 5 or the DHCP helper, or network router, asserted by the RARP-to-DHCP proxy of Figure 6, receives that RARP request from the client and, in step 706, extracts the device identifier from the RARP request. Once the device identifier has been extracted from the RARP request by the RARP-to-DHCP proxy, it generates and transmits a conventional address-based network protocol, such as a DHCP request or BOOTP request using the device identifier that has been extracted, as shown in step 708. The DHCP server then carries out normal processing to select an unused logical network address for the requesting client, using the extracted identifier of the client device, as shown in step 710. For instance, the DHCP server might perform the steps of parsing state and configuration files, and selecting an unused network address. In step 712, the DHCP server transmits the network address to the DHCP gateway, which is received by such in step 714. In step 716, the DHCP gateway generates a standard RARP response to communicate the network address received from the DHCP server. In step 718, the RARP client receives the network address communicated by the DHCP server, and is able to communicate via the network using this network address.

It will be recognized by those skilled in the art that different protocols could be used in the method described in Figure 7 and the configurations shown in Figures 5 and 6. For example, a client using any suitable broadcast-based network protocol could transmit a request for a network address to be granted by a server using an address-based network protocol, by way of a gateway helper or proxy for translation purposes. Therefore, the present invention is not limited to the protocols described herein, but could equally provide for translation between various suitable network address assignment protocols.

From the foregoing, it can be seen that the present invention provides a system and method for communication between two different computer network communications protocols by way of a server-independent gateway. In one embodiment, the present invention provides communication between devices using RARP and DHCP address assignment protocols. The present invention provides a method of assigning a logical network address to a client on a network, wherein the network uses a plurality of protocols for address assignment. Further, the present invention provides a system for handling requests from devices using multiple network protocols, wherein the system comprises a network, a network server using an address-based network protocol, a network client using a broadcast-based network protocol, and a gateway, which is generally assisted by a proxy, for translating between the network server and network client. It will be appreciated by those of ordinary skill in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. For example, the invention has been described in the context of network communications protocols used in a local network, such as an Ethernet network, and an external network, such as the Internet. The particular type of network, either local or external, in which the present invention is used need not be limited to the examples given herein, but rather can include any networks suitable for operation with various computer devices connected via networks. Additionally, specific protocols have been described in connection with embodiments of the present invention; namely, RARP, BOOTP, and DHCP. However, it will be appreciated by those skilled in the art that the present invention need not be limited to these protocols, but rather may be implemented for use with various protocols suitable for the data communications of the present invention of which these examples are a subset.

The present invention also need not be limited to translation between two protocols, but rather could be used to facilitate communication between clients and a server on a network using multiple protocols. The present invention, in such multi-protocol systems would operate in the same manner described herein, by extracting device information from a client's address request, translating the request into a protocol understood by the server, and translating the server's response into a protocol understood by the requesting client. The translations in such a multi-protocol network can be performed between any number of protocols. Additionally, the present invention may make use of multiple clients on a network and not solely one.

The presently disclosed embodiments are, therefore, considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims, rather than the foregoing description, and all changes that come within the meaning in range of equivalents thereof are intended to be embraced therein.

Claims

WHAT IS CLAIMED IS:

1. A method of assigning a network address to a client on network, using a plurality of protocols, comprising the steps of: receiving a request for a network address from a network client using a broadcast-based network protocol; extracting an identification of the client from said request; generating a request using an address-based network protocol, incorporating said extracted identification; processing said request using said address-based network protocol to select network address for said network client; and generating a response to said network client using said broadcast-based network protocol, including said network address.

2. The method of claim 1, wherein said step of processing comprises parsing state and configurations files to assign said network address.

3. The method of claim 1, further comprising the step of selecting an unused network address for the client.

4. The method of claim 1, wherein said broadcast-based network protocol comprises a reverse address resolution protocol (RARP).

5. The method of claim 4, wherein said address-based network protocol comprises a dynamic host configuration protocol (DHCP).

6. The method of claim 4, wherein said address-based network protocol comprises a bootstrap protocol (BOOTP).

7. The method of claim 1, wherein said address-based network protocol comprises a dynamic host configuration protocol (DHCP).

8. The method of claim 1, wherein said address-based network protocol comprises a bootstrap protocol (BOOTP).

9. The method of claim 1, wherein said client comprises an Ethernet network client.

10. The method of claim 9, wherein said identification of the client comprises an Ethernet network identification.

11. The method of claim 1, wherein said network comprises a TCP/IP network.

12. The method of claim 11, wherein said network address comprises an Internet protocol (IP) address.

13. A system for assigning a network address to a client on a network, using a plurality of protocols, comprising: means for receiving a request for a network address from a network client using a broadcast-based network protocol; means for extracting an identification of the client from said request; means for generating a request using an address-based network protocol, incorporating said extracted identification; means for processing said request using said address-based network protocol to select a network address for said network client; and means for generating a response to said network client using said broadcast-based network protocol, including said network address.

14. The system of claim 13, wherein said broadcast-based network protocol comprises a reverse address resolution protocol (RARP).

15. The system of claim 14, wherein said address-based network protocol comprises a dynamic host configuration protocol (DHCP).

16. The system of claim 14, wherein said address-based network protocol comprises a bootstrap protocol (BOOTP).

17. The system of claim 13, wherein said address-based network protocol comprises a dynamic host configuration protocol (DHCP).

18. The system of claim 13, wherein said address-based network protocol comprises a bootstrap protocol (BOOTP).

19. The system of claim 13, wherein said client comprises an Ethernet network client.

20. The system of claim 19, wherein said identification of the client comprises an Ethernet address.

21 The system of claim 13 wherein said external network comprises a TCP/IP network.

22. The system of claim 21, wherein said network address comprises an Internet protocol (IP) address.

23. A system for handling requests from devices using multiple network protocols, wherein said system comprises: at least one device connected to a network; a network server communicating using a broadcast-based network protocol; at least one network client, communicating using an address-based network protocol; and a gateway connected to said network server and said at least one network client for translating requests from said network client, using said address-based network protocol, into requests using said broadcast-based network protocol for handling by said network server, and for translating responses from said network server using said broadcast-based network protocol into responses using said address-based network protocol for said network client.

24. The system of claim 23, comprising a proxy for assisting said gateway in translating requests and responses between the protocols.

25. The system of claim 23, wherein said requests from said network client comprise requests for assignment of a network addresses.

26. The system of claim 23, wherein said requests comprises reverse address resolution protocol (RARP) requests.

27 The system of claim 26, wherein said address-based network protocol comprises a dynamic host configuration protocol (DHCP).

28. The system of claim 26, wherein said address-based network protocol comprises a bootstrap protocol (BOOTP).

29. The system of claim 23, wherein said address-based network protocol comprises a dynamic host configuration protocol (DHCP).

30. The system of claim 23, wherein said address-based network protocol comprises a bootstrap protocol (BOOTP).

31. The system of claim 23, wherein said network server and network client are connected by way of an Ethernet network.

32. The system of claim 31, wherein said network address is issued based on an Ethernet network device identification.

33. The system of claim 23, wherein said network comprises a TCP/IP network.

34. The system of claim 23, wherein said requests from said network client request a network address.

35. The system of claim 34, wherein said network address comprises an

Internet protocol (IP) address.

36. The system of claim 23, wherein said gateway is located on a router between portions of a local network.

37. The system of claim 36, wherein said network server resides on one of said portions of said local network, and said network client resides on a separate one of said portions of said local network, said portions being separated by said router.

38. The system of claim 23, wherein said gateway is located on a router between two separate, local networks.

39. The system of claim 38, wherein said network server resides on one of said two separate, local networks, and said network client resides on a separate one of said two separate, local networks, the two local networks being separated by said router.

40 An address server gateway for use in a computer system of a type having at least one device which employs a broadcast-based network protocol to transmit requests for a network address and a server which operates in accordance with an address-based network protocol to service requests for network addresses, comprising a gateway which (i) receives a request transmitted in accordance with said broadcast-based network protocol and extracts therefrom an identification of the device which transmitted the received request; (ii) generates a request that conforms to said address-based network protocol and includes the extracted identification; (iii) receives a response from the server that provides a requested address; and (iv) transmits the requested address provided by the response in accordance with said broadcast-based network protocol.

41. The address server gateway of claim 40, wherein said device is located on a first network and said server is located on a second network, and wherein said gateway is contained within a router that connects the first and second networks.

42. The address server of claim 40, wherein said broadcast-based network protocol is RARP.

43. The address server of claim 42, wherein said address-based network protocol is DHCP.

44. The address server of claim 42, wherein said address-based network protocol is BOOTP.

45. The address server of claim 40, wherein said address-based network protocol is DHCP.

46. The address server of claim 40, wherein said address-based network protocol is BOOTP.

47. The address server of claim 40, wherein said identification is an Ethernet address.

48. The address server of claim 40, wherein said requested address is an IP address.

49. A computer program for use in a computer system of a type having at least one device which employs a broadcast-based network protocol to transmit requests for a network address and a server which operates in accordance with an address-based network protocol to service requests for network addresses, which executes the following steps:

(i) receiving a request transmitted in accordance with said broadcast-based network protocol and extracting therefrom an identification of the device which transmitted the received request;

(ii) generating a request that conforms to said address-based network protocol and includes the extracted identification;

(iii) receiving a response from the server that provides a requested address; and (iv) transmitting the requested address provided by the response in accordance with said broadcast-based network protocol.

50. The computer program of claim 49, wherein said first protocol is RARP.

51. The computer program of claim 50, wherein said second protocol is DHCP.

52. The computer program of claim 50, wherein said second protocol is BOOTP.

53 The computer program of claim 49, wherein said second protocol is DHCP.

54. The computer program of claim 49, wherein said second protocol is

BOOTP.

55. The computer program of claim 49, wherein said identification is an Ethernet address.

56. The computer program of claim 49, wherein said requested address is an IP address.