DUPLICATE IP ADDRESS DETECTION BY A DHCP RELAY AGENT

• US 20130166737A1
• Filed: 12/10/2012
• Published: 06/27/2013
• Est. Priority Date: 12/22/2011
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Christenson, David A., Venuto, James
• Granted Patent: US 9,774,487 B2
• Time in Patent Office: Days
• US Class Current: 709/224
• CPC Class Codes: H04L 61/103 across network layers, e.g. resolution of network layer into physical layer addresses or address resolution protocol [ARP]
• CPC Class Codes: H04L 61/5014 using dynamic host configuration protocol [DHCP] or bootstrap protocol [BOOTP]
• CPC Class Codes: H04L 61/5046 Resolving address allocation conflicts; Testing of addresses testing when self-assigning an address H04L61/5092
• CPC Class Codes: H04L 67/025 for remote control or remote monitoring of applications
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06
• CPC Class Codes: H04N 21/61 Network physical structure; Signal processing H04B takes precedence

Abstract

Techniques are described for detecting duplicate IP addresses at a DHCP relay agent. Embodiments identify a list of DHCP clients that have valid IP address leases from one or more DHCP servers. Additionally, network traffic from a first node passing through the DHCP relay agent is monitored. Embodiments then determine whether the first node is using a duplicate IP address, based on the monitored network traffic and the identified list of DHCP clients.

Claims

1. A method of detecting duplicate IP addresses, comprising:

identifying a list of DHCP clients that have valid IP address leases from one or more DHCP servers;

monitoring, at the DHCP relay agent, network traffic from a first node passing through the DHCP relay agent; and

determining whether the first node is using a duplicate IP address, based on the monitored network traffic and the identified list of DHCP clients.

2. The method of claim 1, wherein identifying the list of DHCP clients that have valid IP address leases further comprising:

retrieving DHCP server configuration information specifying a configuration of one or more DHCP servers; and

monitoring, at a DHCP relay agent, DHCP lease traffic between the one or more DHCP servers and one or more DHCP clients passing through the DHCP relay agent to collect DHCP lease data.

3. The method of claim 1, further comprising:

upon determining that the first node is using a duplicate IP address, generating a notification identifying the first node and the duplicate IP address.

4. The method of claim 1, further comprising:

upon determining that the first node is using a duplicate IP address, dropping, at the DHCP relay agent, all subsequent packets received from the first node.

5. The method of claim 1, further comprising:

retrieving a list of IP addresses that one or more DHCP servers are configured to lease to clients;

determining whether the first node is using a potential duplicate IP address, based on the retrieved list of IP addresses; and

upon determining that the first node is using a potential duplicate IP address, dropping, at the DHCP relay agent, all subsequent packets received from the first node.

6. The method of claim 1, further comprising:

retrieving a list of IP addresses that one or more DHCP servers are configured to lease to clients;

determining whether the first node is using a potential duplicate IP address, based on the retrieved list of IP addresses; and

upon determining that the first node is using a potential duplicate IP address, transmitting a request for the potential duplicate IP address on behalf of the first node to a DHCP server.

7. The method of claim 1, wherein the one or more DHCP servers are located on a first subnet, wherein the one or more DHCP clients are located on a second subnet that is different from the first subnet, and wherein the DHCP relay agent is configured to relay traffic between the first subnet and the second subnet.

8. The method of claim 1, further comprising:

transmitting an ARP announcement on behalf of one of the DHCP clients in the list of DHCP clients having valid IP address leases, wherein at least one entity on the subnet is configured to update an ARP cache based on the transmitted ARP announcement.