# US 9,521,110 B2 · Method and system for handling a dynamic host configuration protocol internet protocol version 4 address release

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- Number: US 9,521,110 B2
- Document ID: US9521110B2
- Status: Granted
- Kind: B2
- Application number: 14/579,376
- Filed: 2014-12-22
- Published: 2015-04-23
- Granted: 2016-12-13
- Earliest claimed: 2008-08-14
- Assignees: Samsung Electronics Co., Ltd.
- Applicants: Samsung Electronics Co., Ltd.
- Inventors: Sungho Choi; Erik Guttman; Rahul Suhas Vaidya
- Web page: https://patentgrep.com/patent/US9521110B2

## CPC

- H04L 61/5014: using dynamic host configuration protocol [DHCP] or bootstrap protocol [BOOTP]
- H04L 61/251: between different IP versions
- H04L 61/5076: Update or notification mechanisms, e.g. DynDNS
- H04W 80/04: Network layer protocols, e.g. mobile IP [Internet Protocol]
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

Methods and apparatuses are provided for releasing an internet protocol (IP) address by a packet data network gateway (PGW) in a mobile communication system. The PGW allocates an IP version 4 (IPv4) address and an IP version 6 (IPv6) address to a terminal to establish a packet data network (PDN) connection between the terminal and the PGW. The PGW identifies a PDN type associated with the PDN connection if an event of releasing the IPv4 address has occurred. The PGW transmits, to a serving gateway (SGW), a binding revocation message, including information indicating release of the IPv4 address, with the PDN connection remaining, if the PDN type is IPv4 and IPv6. The PGW receives a binding revocation acknowledge message in response to the binding revocation request message, from the SGW.

## Claims

### Claim 1

A method for releasing an internet protocol (IP) address by a packet data network gateway (PGW) in a mobile communication system, the method comprising:
allocating an IP version 4 (IPv4) address and an IP version 6 (IPv6) address to a terminal to establish a packet data network (PDN) connection between the terminal and the PGW;
detecting release of the IPv4 address allocated to the terminal;
identifying a PDN type associated with the PDN connection in response to detecting the release of the IPv4 address;
transmitting to a serving gateway (SGW), a binding revocation message if the identified PDN type is IPv4 and IPv6, the binding revocation message including information indicating that the IPv4 address is released and the PDN connection is maintained; and
receiving, from the SGW, a binding revocation acknowledge message in response to the binding revocation request message.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
determining that the event of releasing the IPv4 address has occurred if the PGW receives a dynamic host configuration protocol (DHCP) release request from the SGW.

### Claim 3 (depends on 2)

The method of claim 2, wherein the DHCP release request message is relayed by a DHCP relay in the SGW to a DHCP server in the PGW.

### Claim 4 (depends on 1)

The method of claim 1, wherein the PGW is configured to act as a DHCP version 4 (DHCPv4) server.

### Claim 5 (depends on 1)

The method of claim 1, wherein the SGW is configured to act as a DHCPv4 relay agent.

### Claim 6

A packet data network gateway (PGW) in a mobile communication system, the PGW comprising:
a transceiver for transmitting and receiving a signal; and
a controller for allocating an IP version 4 (IPv4) address and an IP version 6 (IPv6) address to a terminal to establish a packet data network (PDN) connection between the terminal and the PGW, for detecting release of the IPv4 address allocated to the terminal, for identifying a PDN type associated with the PDN connection in response to detecting the release of the IPv4 address, for transmitting, to a serving gateway (SGW), a binding revocation message if the identified PDN type is IPv4 and IPv6, the binding revocation message including information indicating that the IPv4 address is released and the PDN connection is maintained, and for receiving, from the SGW, a binding revocation acknowledge message in response to the binding revocation message.

### Claim 7 (depends on 6)

The PGW of claim 6, wherein the controller determines that an event of releasing the IPv4 address has occurred if the PGW receives a dynamic host configuration protocol (DHCP) release request from the SGW.

### Claim 8 (depends on 7)

The PGW of claim 7, wherein the DHCP release request message is relayed by a DHCP relay in the SGW to a DHCP server in the PGW.

### Claim 9 (depends on 6)

The PGW of claim 6, wherein the PGW is configured to act as a DHCP version 4 (DHCPv4) server.

### Claim 10 (depends on 6)

The PGW of claim 6, wherein the SGW is configured to act as a DHCPv4 relay agent.