# US 9,438,557 B2 · Adaptive dynamic host configuration protocol assignment with virtual local area network pool > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,438,557 B2 - Document ID: US9438557B2 - Status: Granted - Kind: B2 - Application number: 14/263,622 - Filed: 2014-04-28 - Published: 2015-10-29 - Granted: 2016-09-06 - Earliest claimed: 2014-04-28 - Assignees: Aruba Networks, Inc. - Applicants: Aruba Networks, Inc. - Inventors: Avignan Chatterjee; Harsha Nagaraja; Isaac Theogaraj; Pradeep Iyer - Web page: https://patentgrep.com/patent/US9438557B2 ## CPC - H04L 61/5014: using dynamic host configuration protocol [DHCP] or bootstrap protocol [BOOTP] - H04L 12/4641: {Virtual LANs, VLANs, e.g. virtual private networks [VPN] (LAN interconnection over a bridge based backbone H04L12/462; encapsulation techniques H04L12/4633; routing of packets H04L45/00; packet switches H04L49/00; virtual private networks for security H04L63/0272)} - H04L 12/4679: {Arrangements for the registration or de-registration of VLAN attribute values, e.g. VLAN identifiers, port VLAN membership} - H04L 61/5061: Pools of addresses - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract The present disclosure discloses a method and network device for adaptive DHCP assignment with VLAN pool. Specifically, a network device can assign a client device to a first Virtual Local Area Network (VLAN). The network device then detects a first DHCP Discover message, transmitted by a client device, corresponding to a first VLAN. Also, the network device determines that no DHCP offer message, responsive to the first DHCP Discover message, is transmitted to the client device. Then, the network device transmits on behalf of the client device a second DHCP Discover message for the second VLAN to a DHCP server, and receives a DHCP Offer message in response to the second DHCP Discover message. The network device then assigns the client device to a second VLAN, and subsequently transmits the DHCP Offer message for the second VLAN to the client device. ## Claims ### Claim 1 A non-transitory computer readable medium comprising instructions which, when executed by one or more hardware processors, causes performance of operations comprising: assigning a client device to a first Virtual Local Area Network (VLAN); detecting a first DHCP Discover message, transmitted by the client device, corresponding to the first VLAN; determining that no DHCP offer message, responsive to the first DHCP Discover message, is transmitted to the client device; and responsive at least to determining that no DHCP offer message is transmitted to the client device in response to a threshold number of DHCP Discover messages transmitted by the client device, assigning the client device to a second VLAN. ### Claim 2 (depends on 1) The medium of claim 1, wherein assigning the second VLAN to the client device is further based on determining that an Internet Protocol (IP) address is available on the second VLAN. ### Claim 3 (depends on 1) The medium of claim 1, wherein assigning the client device to the second VLAN is further responsive to: transmitting, by a network device, a second DHCP Discover message corresponding to a second VLAN; receiving, by the network device, a DHCP offer message corresponding to the second DHCP Discover message. ### Claim 4 (depends on 1) The medium of claim 1, wherein the second DHCP Discover message is generated by a network device and incorrectly identifies the client device as a source of the second DHCP Discover message. ### Claim 5 (depends on 1) The medium of claim 1, wherein assigning the client device to the second VLAN is further response to: transmitting, by a network device, a plurality of DHCP Discover messages corresponding to a plurality of VLANs other than the first VLAN; and receiving, by the network device, at least a DHCP offer message corresponding to a second DHCP Discover message corresponding to the second VLAN. ### Claim 6 (depends on 1) The medium of claim 1, wherein the operations further comprise: transmitting, by a network device, a second DHCP Discover message corresponding to a second VLAN, receiving, by the network device, a first DHCP offer message corresponding to the second DHCP Discover message; transmitting, by the network device, a third DHCP Discover message corresponding to a third VLAN; receiving, by the network device, a second DHCP offer message corresponding to the third DHCP Discover message; transmitting, by the network device, a DHCP request message corresponding to the second DHCP offer message; receiving, by the network device, a DHCP assignment corresponding to the DHCP request message; and transmitting, by the network device, a DHCP release message corresponding to the DHCP assignment. ### Claim 7 (depends on 1) The medium of claim 1, wherein the detecting operation is performed by a controller associated with the client device. ### Claim 8 (depends on 1) The medium of claim 1, wherein the operations further comprise determining that no IP addresses are available on the first VLAN and refraining from assigning a client device to the first VLAN based on determining that no IP addresses are available on the first VLAN. ### Claim 9 (depends on 1) The medium of claim 1, wherein the operations further comprise determining that no IP addresses are available on the first VLAN and transmitting information to a plurality of network devices indicating that no IP addresses are available on the first VLAN. ### Claim 10 (depends on 9) The medium of claim 9, wherein determining that no IP addresses are available on the first VLAN is responsive to determining that no DHCP offer message is received in response to a plurality of DHCP Discover messages corresponding to the first VLAN and transmitted by one or more client devices. ### Claim 11 (depends on 1) The medium of claim 1, wherein the detecting operation is performed by snooping, by an intermediate device, a message transmitted by the client device to a DHCP server. ### Claim 12 (depends on 1) The medium of claim 1, wherein assigning the client device to the second VLAN is further based on selecting the second VLAN from a plurality of VLANs based on: a responsive time associated with DHCP Offer messages for DHCP Discover messages corresponding to the second VLAN. ### Claim 13 (depends on 1) The medium of claim 1, wherein assigning the client device to the second VLAN is further based on selecting the second VLAN from a plurality of VLANs based on: a link bandwidth between at least one network device outside of the second VLAN and at least on network device in the second VLAN. ### Claim 14 (depends on 1) The medium of claim 1, wherein assigning the client device to the second VLAN is further based on selecting the second VLAN from a plurality of VLANs based on: a number of client devices on the second VLAN. ### Claim 15 (depends on 1) The medium of claim 1, wherein assigning the client device to the second VLAN comprises updating information on a network device indicating that the client device is assigned to the second VLAN, and wherein the operations further comprise: transmitting, by a network device on behalf of the client device and to a DHCP server, a second DHCP Discover message for the second VLAN, receiving, by the network device, a DHCP Offer message in response to the second DHCP Discover message; and subsequent to assigning the client device to the second VLAN: transmitting, the DHCP Offer message for the second VLAN, to the client device. ### Claim 16 (depends on 15) The medium of claim 15, wherein the client device transmits a DHCP request message to the DHCP server in response to receiving the DHCP offer message from the network device. ### Claim 17 (depends on 15) The medium of claim 15, wherein assigning the client device to the second VLAN comprises: generating and storing a first set of one or more entries indicating that the client device is assigned to the second VLAN; subsequent to generating and storing the first set of entries, deleting a second set of one or more entries indicating that the client device is assigned to the first VLAN. ### Claim 18 A system comprising: a hardware processor; the hardware processor being configured to perform operations comprising: assigning a client device to a first Virtual Local Area Network (VLAN); detecting a first DHCP Discover message, transmitted by the client device, corresponding to the first VLAN; determining that no DHCP offer message, responsive to the first DHCP Discover message, is transmitted to the client device; and responsive at least to determining that no DHCP offer message is transmitted to the client device in response to a threshold number of DHCP Discover messages transmitted by the client device, assigning the client device to a second VLAN. ### Claim 19 (depends on 18) The system of claim 18, wherein the operations further comprise: transmitting, by a network device on behalf of the client device and to a DHCP server, a second DHCP Discover message for the second VLAN, receiving, by the network device, a DHCP Offer message in response to the second DHCP Discover message; and subsequent to assigning the client device to the second VLAN: transmitting, the DHCP Offer message for the second VLAN, to the client device.