IP Library › Granted Patent US 12695721
Granted Patent B2
US 12695721 · App. 18/826,319 · Granted Jul 28, 2026

Synchronizing dynamic host configuration protocol snoop information

Inventors: Ali Sajassi (Alamo, CA); Samir Thoria (Saratoga, CA); Lukas Krattiger (Pleasanton, CA); Manoj Kumar Pandey (San Ramon, CA)
Assignee: Cisco Technology, Inc.
H04L61/5053H04L61/5014H04L63/0236H04L63/101H04L2101/622
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Quick Facts
Patent No.
US 12695721
App. No.
18/826,319
Granted
Jul 28, 2026
Kind
B2
Abstract

Systems and techniques are provided for synchronizing DHCP snoop information. In some examples, a method can include, performing, by a first PE device from a plurality of PE devices, DHCP snooping of a first plurality of DHCP messages between a DHCP client and a DHCP server, wherein the plurality of PE devices is part of an ethernet segment for multihoming the DHCP client. In some aspects, the method includes determining, based on snooping the first plurality of DHCP messages, an association between an IP address corresponding to the DHCP client and a MAC address corresponding to the DHCP client. In some examples, the method includes sending, by the first PE device to at least one other PE device from the plurality of PE devices, a first route advertisement that includes the association between the IP address corresponding to the DHCP client and the MAC address corresponding to the DHCP client.

Claims (50)

1 . A method comprising:

performing, by a first provider edge device (first PE device) from a plurality of PE devices, dynamic host configuration protocol snooping (DHCP snooping) between a DHCP client and a DHCP server, wherein the DHCP snooping comprises:

receiving, by the first PE device, a first message broadcasted by the DHCP server to the plurality of PE devices, wherein the first message is directed to the DHCP client;

determining, by the first PE device, that the first message corresponds to a second message forwarded by the first PE device from the DHCP client to the DHCP server; and

sending, by the first PE device, the first message to the DHCP client;

determining, based on the DHCP snooping, that the DHCP client is secure;

sending, by the first PE device to at least one other PE device, a first route advertisement that includes an indication; and

configuring the at least one other PE device to validate network traffic associated with the DHCP client based on the indication.

2 . The method of claim 1 , wherein each of the plurality of PE devices is configured as a DHCP relay agent.

3 . The method of claim 1 , wherein the plurality of PE devices is configured with an access control list (ACL) for evaluating DHCP messages.

4 . The method of claim 1 , further comprising:

receiving, by the first PE device from the at least one other PE device from the plurality of PE devices, a second route advertisement that includes an association between an internet protocol address (IP address) corresponding to the DHCP client and a media access control address (MAC address) corresponding to the DHCP client.

5 . The method of claim 4 , wherein the at least one other PE device is configured to perform snooping of a second plurality of DHCP messages, wherein the second plurality of DHCP messages are associated with a lease renewal of the IP address corresponding to the DHCP client.

6 . The method of claim 4 , further comprising:

receiving, by the first PE device, a DHCP request message from the DHCP client, wherein the DHCP request message is associated with a lease renewal of the IP address corresponding to the DHCP client; and

sending, by the first PE device to the at least one other PE device, a third route advertisement that includes the association between the IP address corresponding to the DHCP client and the MAC address corresponding to the DHCP client, wherein the third route advertisement further includes an indication for synchronizing the DHCP request message among the first PE device and the at least one other PE device.

7 . An apparatus comprising:

a processor for executing instructions stored in memory, wherein execution of the instructions by the processor executes:

performing, by a first provider edge device (first PE device) from a plurality of PE devices, dynamic host configuration protocol snooping (DHCP snooping) between a DHCP client and a DHCP server, wherein the DHCP snooping comprises:

receiving, by the first PE device, a first message broadcasted by the DHCP server to the plurality of PE devices, wherein the first message is directed to the DHCP client;

determining, by the first PE device, that the first message corresponds to a second message forwarded by the first PE device from the DHCP client to the DHCP server; and

sending, by the first PE device, the first message to the DHCP client;

determining, based on the DHCP snooping, that the DHCP client is secure;

sending, by the first PE device to at least one other PE device, a first route advertisement that includes an indication; and

configuring the at least one other PE device to validate network traffic associated with the DHCP client based on the indication.

8 . The apparatus of claim 7 , wherein each of the plurality of PE devices is configured as a DHCP relay agent.

9 . The apparatus of claim 7 , wherein the plurality of PE devices is configured with an access control list (ACL) for evaluating DHCP messages.

10 . The apparatus of claim 7 , further comprising:

receiving, by the first PE device from the at least one other PE device from the plurality of PE devices, a second route advertisement that includes an association between an internet protocol address (IP address) corresponding to the DHCP client and a media access control address (MAC address) corresponding to the DHCP client.

11 . The apparatus of claim 10 , wherein the at least one other PE device is configured to perform snooping of a second plurality of DHCP messages, wherein the second plurality of DHCP messages are associated with a lease renewal of the IP address corresponding to the DHCP client.

12 . The apparatus of claim 10 , further comprising:

receiving, by the first PE device, a DHCP request message from the DHCP client, wherein the DHCP request message is associated with a lease renewal of the IP address corresponding to the DHCP client; and

sending, by the first PE device to the at least one other PE device, a third route advertisement that includes the association between the IP address corresponding to the DHCP client and the MAC address corresponding to the DHCP client, wherein the third route advertisement further includes an indication for synchronizing the DHCP request message among the first PE device and the at least one other PE device.

13 . The apparatus of claim 7 , wherein the first message and the second message are an offer message and a discover message, respectively.

14 . A non-transitory computer readable medium comprising instructions, the instructions, when executed by a computing system, cause the computing system to:

performing, by a first provider edge device (first PE device) from a plurality of PE devices, dynamic host configuration protocol snooping (DHCP snooping) between a DHCP client and a DHCP server, wherein the DHCP snooping comprises:

receiving, by the first PE device, a first message broadcasted by the DHCP server to the plurality of PE devices, wherein the first message is directed to the DHCP client;

determining, by the first PE device, that the first message corresponds to a second message forwarded by the first PE device from the DHCP client to the DHCP server; and

sending, by the first PE device, the first message to the DHCP client;

determining, based on the DHCP snooping, that the DHCP client is secure;

sending, by the first PE device to at least one other PE device, a first route advertisement that includes an indication; and

configuring the at least one other PE device to validate network traffic associated with the DHCP client based on the indication.

15 . The non-transitory computer readable medium of claim 14 , wherein each of the plurality of PE devices is configured as a DHCP relay agent.

16 . The non-transitory computer readable medium of claim 14 , wherein the plurality of PE devices is configured with an access control list (ACL) for evaluating DHCP messages.

17 . The non-transitory computer readable medium of claim 14 , the instructions further causing the computing system to:

receive, by the first PE device from the at least one other PE device from the plurality of PE devices, a second route advertisement that includes an association between an internet protocol address (IP address) corresponding to the DHCP client and a media access control address (MAC address) corresponding to the DHCP client.

18 . The non-transitory computer readable medium of claim 17 , wherein the at least one other PE device is configured to perform snooping of a second plurality of DHCP messages, wherein the second plurality of DHCP messages are associated with a lease renewal of the IP address corresponding to the DHCP client.

19 . The non-transitory computer readable medium of claim 17 , the instructions further causing the computing system to:

receive, by the first PE device, a DHCP request message from the DHCP client, wherein the DHCP request message is associated with a lease renewal of the IP address corresponding to the DHCP client; and

send, by the first PE device to the at least one other PE device, a third route advertisement that includes the association between the IP address corresponding to the DHCP client and the MAC address corresponding to the DHCP client, wherein the third route advertisement further includes an indication for synchronizing the DHCP request message among the first PE device and the at least one other PE device.