(12) United States Patent
`Nurmann
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 6,560,642 B1
`May 6, 2003
`
`US006560642B1
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`9/1996 Norris ................... .. 395/200.1
`2/1999 Bereiter . . . . . . .
`. . . .. 709/220
`5/2000 Fijolek et al.
`709/225
`5/2000 Subramauiam et al.
`709/220
`9/2000 Mellquist .................. .. 709/220
`2/2001 Arbaugh et a1.
`.
`..... .. 713/2
`5/2001 Frajlong et al.
`.......... .. 709/220
`
`5,557,748 A
`5,875,306 A *
`6,058,421 A *
`6,070,187 A *
`6,115,545 A *
`6,185,678 B1 *
`6,230,194 B1 *
`* cited by examiner
`Primary Examiner—Nabil El-Hady
`(74) Attorney, Agent, or Firm—Christ0pher Whewell
`(57)
`ABSTRACT
`
`
`
`This invention relates to a method of establishing an Internet
`Protocol network with several IP hosts and with an IP
`gateway [or connecting the IP network to the Internet. The
`invention provides a method which no longer requires the
`knowledge of address mechanisms of the Internet protocol
`previously necessary for a successful establishment and thus
`protects disturbances of errors during the establishment of
`an Iutemet Protocol network.
`
`12 Claims, 4 Drawing Sheets
`
`(54)
`
`METHOD OF ESTABLISHING AN INTERNET
`PROTOCOL NETWORK UTHJZING IP
`GATEWAY THAT FUNCTIONS AS EITHER
`OR BOTH DHCP CLIENT AND DHCP
`SERVER
`
`(75)
`
`Inventor:
`
`Jens Nurmann, Aachen (DE)
`
`(73)
`
`Assignee: ELSA AG, Aachen (DE)
`
`( * )
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(21) Appl. N0.:
`Filed:
`
`(22)
`
`09/425,863
`
`Oct. 23, 1999
`
`(30)
`
`Foreign Application Priority Data
`
`Oct. 26, 1998
`
`(DE)
`
`....................................... .. 198 49 170
`
`Int. c1.7 ............................................ .. G06F15/177
`(51)
`(52) US. Cl.
`..................... .. 709/220; 709/221; 709/222;
`709/223; 709/224; 709/225
`(58) Field of Search ................................ .. 709/220-225
`
`
`
`'PsELII1P17utiiiAiL1EN1
`SIJEHE NA[H |}[P-SEEVEM
`
` 1F-EATEUA‘!
`
`1P—110RE$E 10.0.0254
`[P-NEIZMASKE 25500.0
`[I-ICP SERVER DNS-SERVER
`0100 1001300103350
`10-+031 'M]1N1E‘
`IP-H081 ‘MP’
`10-+051-000
`1P-A1RESSEID.|J.0.4
`19-1025305 10.0.0.3
`1P-AIZIEESSE 10.0.0.
`1P-NETZHASKE 2
`.0.0.0
`IP—1£1ZMASKE 25500.0
`10-115120100 25500.0
`100115011 10.0.0254
`10-010011 10.0.0254
`1P-mom 10.0.0254
`D18-SERVER 10.0.0254 [NS-SERVER 10.0.0. [1111-SE1211ERl1].11.11.254
`
`
`
`
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`1P-GATEIAY
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`10 0.0.3
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`
`SAMSUNG 1010
`
`1
`
`SAMSUNG 1010
`
`

`
`U.S. Patent
`
`May 6, 2003
`
`Sheet 1 of4
`
`US 6,560,642 B1
`
`2
`
`

`
`U.S. Patent
`
`May 6, 2003
`
`Sheet 2 of 4
`
`US 6,560,642 B1
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`U.S. Patent
`
`May 6, 2003
`
`Sheet 3 of 4
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`US 6,560,642 B1
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`
`U.S. Patent
`
`May 6, 2003
`
`Sheet 4 of 4
`
`US 6,560,642 B1
`
`
`
`IP-EATEHAY
`"PSEL|00'
`[HEP [LIENT
`SUEHE NAEH [I-[P-SERVEH
`
`IP-I-IJST '0NS'
`
`IP-HOST "DI-[P'
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`IP-H031 'NONAHE'
`
`
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`IP-ADRESSE l0.0.0.254
`IP-METZHASKE 255.0.0.0
`0|-[P SERVER. 0N3-SERVER
`SUEHE ABISESEHIBSSEN
`
`IP-HJST '[NS'
`IP-ADRESSE 10.0.0.2
`IP-BETZMASKE 255.0.0.0
`IP-EATEHAY l0.0.0.254
`0NS-SERVER I0.0.0.254
`
`IP-H031 "0H[P'
`IP-AIPESSE |0.0.0.3
`IP-KETZMASKE 25500.0
`IP-EATEHAY l0.0.0.254
`0NS-SERVER |0.0.0.254
`
`IP-HUST 'NONAME"
`IF-ADRESSE 10.0.0.4
`IF-NEIZHASKE 255.0.0.0
`IP-GATEWAY l0.0.0.254
`[NS-SERVER l0.0.0.254
`
`
`
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`11-10s1'01s'
`11-10125ss510.0.0.2
`11=-1151z1111s1<5255.0.0.0
`11=-01151111 10.0.0.1
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`10011011211101 01125115510121
`
`111-1031-0150
`11-10125535 10.0.0.3
`11>-11512111515 25500.0
`15-5111511111 10.0.0.1
`015-551111512 10.0.0.1
`
`11=-511511111
`11-10125555 10.0.0254
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`11>-1151z111s1<5 255.0.0.0
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`0113-551111511 10.0.0.1
`
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`FIGURE 4
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`5
`
`

`
`US 6,560,642 B1
`
`1
`METHOD OF ESTABLISHING AN INTERNET
`PROTOCOL NETWORK UTILIZING IP
`GATEWAY THAT FUNCTIONS AS EITHER
`OR BOTH DHCP CLIENT AND DHCP
`SERVER
`
`FIELD OF THE INVENTION
`
`'lhe present invention relates to a method of establishing 1
`an Internet Protocol (“IP”) network with several IP hosts and
`with an IP gateway for connecting the IP network to the
`internet.
`
`BACKGROUND INFORMATION
`
`Explanation of the concepts used in conjunction with the
`invention:
`
`2
`Usually, additional IP addresses are entered into each IP
`host, converted into symbolic names, e.g., for the Domain
`Name Service (DNS in short) of the IP addresses and vice
`versa. The Domain Name Service is practically indispens-
`able when working in the Internet.
`Another possibility for a new establishment of an IP
`network is that the user allocates an IP address and an IP
`network mask to only one IP host and uses this IP host for
`allocating IP addresses and [P network masks to additional
`0 IP hosts in the IP network. This is carried out by means of
`DHCP (DHCP: Abbreviation for Dynamic Host Configura-
`tion Protocol), which must be installed in the host. The
`DHCP is defined via RFC 2131 and RFC 2132 (See the
`explanations for "“RFC”). The IP host established manually
`by the user functions as DHCP server for the additional IP
`hosts, the DHCP clients. The allocation of the IP addresses
`to the IP hosts functioning as DHCP clients takes place from
`the DHCP server, in which the user transfers IP addresses
`left on the DHCP server from the latter to the DHCP
`
`IP
`address
`
`[P
`network
`mask
`
`An TI’ address is a 32-bit number which is regularly
`represented with four number separated by dots in the so-called
`“dotted notation”. Each of these numbers describes a complete
`bite 8 bits wide. The 32-bit number contains a network address
`as well as a host address which are held apart from one another
`by the IP network mask (Sec “IP network mask” for
`explanation).
`An IP network mask is a 32-bit number represented
`analogously to an IP address. It keeps the network address and
`the host address in the IP address apart from one another by
`logical AND operation, that is, all 1 bits of the network
`mask define the part of the IP address which belongs to the
`network address. (If the network mask is, e.g., 255.000; 255 =
`128+64+32+16+8+4+2+1<:>decimal=
`1 1 1 1 1 1 1 1 binary, the 8 front bits are set. If the network
`mask 255.0.0.0 is now logically “AND” linked, e.g., with an
`IP address 10.0.0.4, the restdt is 10.0.0.0. This result is then the
`network address whereas the host address is the entire IP address
`10.0.0.4. The mode of expression: Host 0.0.4 in the network
`l0.(l.0.I.'l is also customary.
`An ll’ stack is a method which makes possible the
`processing of IP data packets according to TCP/IP-based
`protocols (TCP/IP: Abbreviation for Transmission Control
`Protocol/Internet Protocol) in a computer. The open standards -
`also called RFC (RFC: Abbreviation for “requests for
`comments”) - contain all definitions of the TCP/ll’-based
`protocols. The RFC's are numbered consecutively and are
`available free of charge, e.g., via the Internet. RFC’s
`are never changed. There are at the most supplementary
`or replacing RFC’s.
`An IP host is a computer in which an IP stack has been
`installed.
`An IP gateway is a computer which can execute the
`switching of IP data packets between a computer and a network,
`here the Internet. This computer is provided with an IP stack so
`that it can convert the IP data packets from one transmission
`medium to another transmission medium, e.g., from a LAN
`(LAN: Abbreviation for Local Area Network) to an WAN
`(WAN: Abbreviation for Wide Area Network).
`An ll’ network consists of several [P hosts and an IP
`IP
`network gateway linked to each other for a data transmission.
`
`[P
`stack
`
`[P
`host
`[P
`gateway
`
`Several possibilities are known from the state of the art for
`establishing an IP network:
`The user manually allocates an IP address and an IP
`network mask to each IP host
`in the IP network. Each
`additional IP host which is to be tied into the IP network
`therefore requires an additional establishing cost. The work-
`ing cost includes the fact that the user must know and have
`understood the address mechanisms of the Internet protocol
`since an erroneous establishment of individual IP hosts can
`
`absolutely result in a disturbance in the entire IP network. If
`the user desires to connect the IP network to the Internet he
`requires an IP gateway for this whose IP address must also
`be entered manually in each IP host of the IP network.
`
`clients=IP hosts. This applies to the IP addresses of the IP
`hosts as well as to additional IP addresses, e.g., of a DNS
`server. The connection of the IP gateway to the IP network
`nevertheless requires a manual establishment since the II’
`gateway can not be established from a DHCP server. Even
`in this method of establishing an IP network the user must
`know and have understood the address mechanism of the
`Internet protocol. Only the establishing cost for the IP hosts
`is eliminated.
`
`Therefore, a central disadvantage of the known methods
`is the fact that the user must know and have understood the
`
`address mechanisms of the Internet protocol for a successful
`establishment of the II’ network. Any errors in the estab-
`lishment can absolutely result in a disturbance in the entire
`IP network. The known methods are therefore not suited for
`users without considerable knowledge of the Internet pro-
`tocol.
`
`The invention therefore has the basic problem of creating
`a method of establishing an IP network with several IP hosts
`and with an IP gateway which method requires no knowl-
`edge of the address mechanisms of the Internet protocol for
`a successful establishment and therewith protects against
`disturbances, resulting from errors during the establishing.
`The solution of this problem makes use of the fact that all
`information necessary for establishing an IP network with
`Internet connection converge in the IP gateway.
`The invention is also based on the concept, contrary to the
`traditional method, of at first not using a DHCP server for
`the establishment but rather of allowing the IP gateway to
`find out in the non-established state as DHCP client whether
`
`there is a DHCP server in the IP network already. If there is
`no DHCP server the IP gateway is activated automatically as
`DHCP server. The software (IP stack) for this is imple-
`mented in the firmware of the gateway so that the user is not
`burdened with the installation. The activated DHCP server
`allocates IP addresses and IP network masks to the IP hosts
`in a standard manner from a reserved address range so that
`the IP hosts and the IP gateway can exchange IP data packets
`with each other. Exclusively IP addresses which) are not
`given out in the Internet for IP hosts are normally located in
`the reserved address range.
`The problem is solved by the present invention.
`I-Iowever, If the IP gateway discovers as DHCP client that
`there is a DHCP server in the IP network already the IP
`gateway does not activate its own DHCP server and logs oif
`again in the found DHCP server because an establishment
`and administration of the IP network in a traditional way
`with an IP host as DHCP server is obviously intended.
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`US 6,5 60,642 B1
`
`3
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`In the annexed drawings:
`FIG. 1 shows the components of an IP network according
`to the prior art;
`FIG. 2 shows the components of an IP network according
`to the prior art;
`FIG. 3 shows a non-established IP network suitable for
`use in accordance with the present
`FIG. 4 shows an IP network suitable for use in accordance
`
`with the present invention.
`DETAILED DESCRIPTION
`
`In an embodiment of the invention an access to the
`
`Internet for the individual IP hosts can be prepared in that
`after the allocation of IP addresses and IP network masks to
`at least one IP host a program for configuring the Internet
`access is started. The program starts a broadcast call of the
`IP host to an address, reserved for the broadcast call, of the
`IP gateway functioning as DHCP server. The configuration
`program allocates an IP network mask and IP address to the
`IP gateway from the address range reserved for this under
`which the gateway is detectable if a non-configured IP
`gateway with active DHCP server is present at the reserved
`address for the broadcast call.
`The establishment of the Internet access for the entire IP
`
`network via only one IP host by means of the configuration
`program takes place as follows:
`The IP host selected for the configuration determines by
`means of the locality criterion whether an IP address of
`another IP host in another IP network (target IP address) is
`present with which one of the IP hosts of the local IP
`network would like to make contact. The target IP address
`can be accessible, e.g., via an Internet provider or by direct
`connection to the other IP network. It sends all IP packets
`determined for IP addresses which are not located in the
`
`local IP network of the IP host selected for the configuration
`to its responsible default IP gateway. The IP gateway must
`now decide using the target IP address where it must
`retransmit the IP packet to. To this end there is an IP routing
`table in the IP gateway which defines a linking of IP
`addresses and targets. The configuration tool now enters a
`default route in the IP gateway which route transfers all IP
`packets with target IP addresses outside of the local IP
`network to an Internet provider. This takes place, eg, in an
`ISDN dial connection to the Internet provider by means of
`the automatic design of the default route as soon as an IP
`packet is to be transferred to the Internet provider in case this
`connection is not already present.
`The user receives the data necessary for the configuration,
`including, among other things, a DNS IP address, from his
`Internet provider. The access to the Internet via the Internet
`provider functions thereby with an address translation tech-
`nology for IP addresses (known as IP masquerading) so that
`the IP addresses given out internally in the IP network are
`not passed on to the provider and into the Internet. As soon
`as the Internet access has been configured via the gateway,
`accesses to the Internet via the IP gateway are possible by
`any IP hosts in the IP network. The IP gateway administers
`thereby the IP masquerading out of and into the reserved
`address range as well as for inquiries for the conversion of
`symbolic names into IP addresses and vice versa (DNS).
`The main advantage of the invention is the fact that the
`expense for establishment is significantly reduced since all
`IP addresses and IP network masks in the IP gateway
`necessary for the operation of the IP network have been filed
`
`4
`in the address range reserved to this end. A further central
`advantage is the fact
`that misconfigurations are avoided
`since all IP addresses and IP network masks for further IP
`
`hosts in the IP network are centrally given out by the IP
`gateway.
`The method is designed so that it can also be used without
`problems in already existing IP networks for their
`re-establishment.
`
`10
`
`FIGS. 1 to 4 are referred to in order to explain the state
`of the art and the invention.
`
`In the traditional establishing of an IP network several
`individual configurations are necessary in the IP hosts and
`the IP gateway in a certain sequence before IP packets can
`be transmitted within the IP network and, if necessary, to
`another transmission medium, e.g.,
`the Internet. FIG. 1
`shows the components of an IP network which the user of
`traditional methods must configure.
`FIG. 2 shows the typical scope of a ready-configured IP
`network with connection to the Internet. In addition to the IP
`
`address and the IP network mask for the particular IP host
`the IP address of the IP gateway must be manually entered
`in each IP host of the IP network for the Internet connection.
`
`In addition, the address for the domain name service (DNS
`in short) must be entered in each IP host. The DNS converts
`IP addresses into symbolic names and vice versa.
`FIG. 3 shows a non-established IP network, that is, the
`initial situation for the method in accordance with the
`invention. The symbolic names of the IP hosts “DNS,
`DHCP, NoName” are entered manually by the user. Usually,
`a modern IP stack installed in each of the connected IP hosts
`provides an inquiry to the user about such a symbolic name
`during the installation. In addition, the IP stacks can operate
`as a DHCP client. The IP gateway functions for the con-
`nection to the Internet.
`
`FIG. 4 illustrates that, counter to the traditional method,
`at first no DHCP server is used for the establishment but
`rather the IP gateway finds out in the non-established state
`as DHCP client whether there is a DHCP server in the IP
`network already (first line of FIG. 4). If there is no DHCP
`server the IP gateway is automatically activated as a DHCP
`server under the IP address 10.0.0.254 with the network
`mask 225.000 and assures that
`in the future all DNS
`inquiries are passed on to a DNS server. As regards the local
`IP network with its IP hosts the IP gateway acts as a DNS
`server; as regards the Internet the IP gateway acts as a DNS
`client which routs onward the DNS inquiries of the IP hosts
`of the local IP network. The professional terminology states
`that the IP gateway establishes a DNS forwarder (second
`line of FIG. 4).
`The activated DIICP server allocates IP addresses
`10.0.0.2, 10.0.0.3, 10.0.0.4 and IP network masks 225.0.0.0
`to the IP hosts “DNS, DHCP, NoName” according to the
`standard from a reserved address range so that the IP hosts
`and the IP gateway can exchange IP data packets among
`each other.
`In addition, the access to the Internet for the IP hosts
`“DNS, DHCP, NoName” is prepared in that after the allo-
`cation of the IP addresses and IP network masks a program
`for configuring the Internet access is started, e.g., on the IP
`host “DNS”. The program starts a broadcast call of the IP
`host “DNS” to an address of the IP gateway functioning as
`DHCP server which address is reserved for the. broadcast
`
`call. The configuration program allocates the IP network
`mask 255.0.0.0 and IP address 10.0.0.1 from the address
`range reserved for this purpose to the IP gateway under
`which the gateway is detectable by the IP hosts for the
`
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`

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`US 6,560,642 B1
`
`5
`Internet access. Aprerequisite for this is that the IP gateway
`has not yet been configured and that an active DHCP server
`is present (third line of FIG. 4).
`After the conclusion of the complete configuration the IP
`network like the one in FIG. 4, line four, is present.
`What is claimed is:
`
`1. A method of establishing an IP network with several IP
`hosts and with an IP gateway for connecting the IP network
`to the Internet, characterized in that:
`An IP stack is installed in each IP host which stack can
`function as a DHCP client,
`An IP stack is installed in the IP gateway which stack can
`function both as a DHCP client and as a DHCP server,
`After having been activated, the IP gateway functions at
`first as a DHCP client and checks whether a DHCP
`
`server is present in the IP network, and
`If no DHCP server is present in the IP network the DHCP
`server in the IP gateway activates itself and allocates IP
`addresses and IP network masks to each activated IP
`host from a reserved address range.
`2. The method according to claim 1, characterized in that
`the IP address allocated to each IP host is routed onward to
`
`the Internet by means of known address translation tech-
`nologies.
`3. A method of establishing an IP network with several IP
`hosts and with an IP gateway for connecting the IP network
`to the Internet, characterized in that:
`An IP stack is installed in each IP host which stack can
`function as a DHCP client,
`An IP stack is installed in the IP gateway which stack can
`function both as a DHCP client and as a DHCP server,
`After having been activated, the IP gateway functions at
`first as a DHCP client and checks whether a DHCP
`server is present in the IP network, and
`If no DHCP server is present in the IP network the DHCP
`server in the IP gateway activates itself and allocates IP
`addresses and IP network masks to each activated IP
`host from a reserved address range and further charac-
`terized in that after the allocation of the IP addresses
`and IP network masks a program for configuring the
`Internet access is started on at least one IP host which
`program starts a broadcast call of the IP host to an
`address, reserved for the broadcast call, of the IP
`gateway functioning as DHCP server and that
`the
`configuration program allocates an IP address and an IP
`network mask from the reserved address range to the IP
`gateway under which the gateway can be detected if a
`non-configured IP gateway with active DHCP server is
`present at the reserved address.
`4. The method according to claim 3, characterized in that
`the IP address allocated to each IP host is routed onward to
`
`the Internet by means of known address translation tech-
`nologies.
`5. An IP network capable of being connected to the
`Internet, comprising:
`a) a plurality of IP host computers each having a first IP
`stack installed therein, wherein said first IP stack is
`capable of functioning as a DHCP client;
`b) at
`least one IP gateway, having a second IP stack
`installed therein, wherein said second IP stack is
`capable of functioning as either or both a DHCP client
`and as a DHCP server,
`
`10
`
`15
`
`25
`
`30
`
`35
`
`40
`
`45
`
`6
`wherein said IP gateway includes a means for determining
`whether a DHCP server is present in said network.
`6. An IP network according to claim 5 wherein said IP
`gateway f11rther includes a means for activating itself as
`DHCP server.
`
`7. An IP network according to claim 5 wherein an IP
`gateway is functioning as DHCP server, and further com-
`prising a means for allocating an IP address and an IP
`network mask to each IP host in said network.
`
`8. An IP Network according to claim 7 wherein said IP
`address and said IP network mask are selected from a
`
`reserved address range.
`9. Aprocess for establishing an IP network comprising the
`steps of:
`a) providing a plurality of IP hosts, wherein each IP host
`includes a first IP stack that is capable of functioning as
`a DHCP client;
`b) providing an IP gateway connected to said hosts,
`wherein said gateway includes a second IP stack that is
`capable of functioning as either a DHCP client, or as a
`DHCP server;
`
`c) causing said IP gateway to detect whether a DHCP
`server is present in said network;
`d) causing said IP gateway to become active as a DHCP
`server in cases when no DHCP server is detected; and
`e) causing said IP gateway to allocate IP addresses and IP
`network masks to each [P host in said network.
`10. A process for establishing an IP network comprising
`the steps of:
`a) providing a plurality of IP hosts, wherein each IP host
`includes a first IP stack that is capable of functioning as
`a DHCP client;
`b) providing an IP gateway connected to said hosts,
`wherein said gateway includes a second IP stack that is
`capable of functioning as either a DHCP client, or as a
`DHCP server;
`c) causing said IP gateway to detect whether a DHCP
`server is present in said network;
`d) causing said IP gateway to become active as a DHCP
`server in cases when no DHCP server is detected;
`e) causing said IP gateway to allocate IP addresses and IP
`network masks to each IP host in said network; and
`f) initiating a program for configuring Internet access on
`at least one IP host,
`wherein said program starts a broadcast call of the IP host to
`an address, said address having been previously reserved for
`such a broadcast call, to an address of the IP gateway (when
`said IP gateway is functioning in its DHCP server capacity),
`and wherein said program allocates an IP address and an IP
`network mask from a reserved address range to the IP
`gateway through which a non-configured IP gateway may be
`detected when an active DHCP server is present at the
`reserved address.
`
`60
`
`11. The process of claim 10 wherein the IP address
`allocated to said IP hosts is routed to the Internet by means
`of known address translation technologies.
`12. The process of claim 9 wherein the IP address
`allocated to said IP hosts is routed to the Internet by means
`of known address translation technologies.
`
`*
`
`*
`
`*
`
`*
`
`*
`
`8