Network-based DHCP server recovery
To recover existing IP configuration information directly from an existing network in response to DHCP server failure, unique identifiers corresponding to hosts that a DHCP server provisioned with IP configuration information may be stored on the network in non-volatile memory such that current configuration information associated with the hosts may be obtained from the network in response to the DHCP server failure. For example, in a standalone deployment, messages may be sent to each host, which may respond with the current configuration information. In other scenarios, a summary node may provide summarized configuration information and messages may only be sent to hosts not included among the summarized configuration information, or configuration information may be synchronized among redundant DHCP servers such that messages may be sent to certain hosts based on differences between the configuration information on a mate DHCP server and a DHCP server recovering from failure.
1. A method for providing network-based Dynamic Host Configuration Protocol (DHCP) server recovery, comprising:
storing unique identifiers that correspond to one or more hosts in a network that a DHCP server has provisioned with Internet Protocol (IP) configuration information in non-volatile memory, wherein the unique identifiers uniquely identify the one or more hosts in a routing domain associated with an Open Shortest Path First (OSPF) area, a routing IP address, a subnet mask, and a gateway, wherein the DHCP server provisions the IP configuration information to the one or more hosts in a standalone deployment;
obtaining, from the network, DHCP configuration information currently present on the one or more hosts that correspond to the unique identifiers stored in the non-volatile memory in response to the DHCP server failing;
repopulating a DHCP database associated with the DHCP server based on the DHCP configuration information currently present on the one or more hosts;
sending a configuration query message to each host that corresponds to a unique identifier stored in the non-volatile memory; and
receiving a response to the configuration query message from at least one host that corresponds to a unique identifier stored in the non-volatile memory, wherein the response to the configuration query message includes the DHCP configuration information currently present on the at least one host.
2. The method recited in claim 1 , further comprising:
receiving, from a DHCP summary node, summarized DHCP configuration information that corresponds to one or more hosts in a subnetwork managed with the DHCP summary node, wherein the DHCP configuration information currently present on the one or more hosts includes the summarized DHCP configuration information received from the DHCP summary node.
3. The method recited in claim 1 , wherein the DHCP server comprises a recovering DHCP server that provisions the IP configuration information to the one or more hosts in combination with a mate DHCP server in a redundant deployment, wherein the mate DHCP server is a failover resource that communicates for the DHCP server in response to a failure associated therewith.
4. The method recited in claim 3 , wherein obtaining the DHCP configuration information currently present on the one or more hosts comprises:
updating a local span of configuration list that includes the unique identifiers corresponding to the hosts that the recovering DHCP server has provisioned based on a mate span of configuration list received from the mate DHCP server in response to identifying one or more differences between the local span of configuration list and the mate span of configuration list;
sending a configuration query message to each host that corresponds to a unique identifier in the updated local span of configuration list; and
receiving a response to the configuration query message from at least one host that corresponds to a unique identifier in the updated local span of configuration list, wherein the response to the configuration query message includes the DHCP configuration information currently present on the at least one host.
5. The method recited in claim 4 , wherein obtaining the DHCP configuration information currently present on the one or more hosts further comprises:
updating the mate span of configuration list on the mate DHCP server based on the one or more differences between the local span of configuration list and the mate span of configuration list in response to mate DHCP server failing.
6. The method recited in claim 3 , further comprising:
receiving, from a DHCP summary node, summarized DHCP configuration information that corresponds to one or more hosts in a subnetwork managed with the DHCP summary node, wherein the DHCP configuration information currently present on the one or more hosts includes the summarized DHCP configuration information received from the DHCP summary node.
7. The method recited in claim 1 , further comprising:
receiving, from a DHCP summary node, summarized DHCP configuration information that corresponds to one or more hosts in a subnetwork managed with the DHCP summary node, wherein the DHCP configuration information currently present on the one or more hosts includes the summarized DHCP configuration information received from the DHCP summary node.
8. The method recited in claim 1 , wherein obtaining the DHCP configuration information currently present on the one or more hosts comprises:
determining that the DHCP configuration information currently present on at least one host that corresponds to a unique identifier stored in the non-volatile memory cannot be obtained from the network; and
provisioning the at least one host with new DHCP configuration information, wherein the DHCP configuration information currently present on the one or more hosts includes the new DHCP configuration information provisioned to the at least one host.
9. A Dynamic Host Configuration Protocol (DHCP) server, comprising:
non-volatile memory configured to store unique identifiers that correspond to one or more hosts in a network that the DHCP server has provisioned with Internet Protocol (IP) configuration information, wherein the unique identifiers uniquely identify the one or more hosts in a routing domain associated with an Open Shortest Path First (OSPF) area, a routing IP address, a subnet mask, and a gateway, wherein the DHCP server provisions the IP configuration information to the one or more hosts in a standalone deployment; and
one or more processors configured to:
obtain, from the network, DHCP configuration information currently present on the one or more hosts that correspond to the unique identifiers stored in the non-volatile memory in response to the DHCP server failing;
repopulate a DHCP database associated with the DHCP server based on the DHCP configuration information currently present on the one or more hosts;
send a configuration query message to each host that corresponds to a unique identifier stored in the non-volatile memory; and
receive a response to the configuration query message from at least one host that corresponds to a unique identifier stored in the non-volatile memory, wherein the response to the configuration query message includes the DHCP configuration information currently present on the at least one host.
10. The DHCP server recited in claim 9 , wherein the DHCP server provisions the IP configuration information to the one or more hosts in a standalone deployment and the one or more processors are further configured to:
receive, from a DHCP summary node, summarized DHCP configuration information that corresponds to one or more hosts in a subnetwork managed with the DHCP summary node, wherein the DHCP configuration information currently present on the one or more hosts includes the summarized DHCP configuration information received from the DHCP summary node.
11. The DHCP server recited in claim 9 , wherein the DHCP server comprises a recovering DHCP server that provisions the IP configuration information to the one or more hosts in combination with a mate DHCP server in a redundant deployment, wherein the mate DHCP server is a failover resource that communicates for the DHCP server in response to a failure associated therewith, and the one or more processors are further configured to:
update a local span of configuration list that includes the unique identifiers corresponding to the hosts that the recovering DHCP server has provisioned based on a mate span of configuration list received from the mate DHCP server in response to identifying one or more differences between the local span of configuration list and the mate span of configuration list;
send a configuration query message to each host that corresponds to a unique identifier in the updated local span of configuration list; and
receive a response to the configuration query message from at least one host that corresponds to a unique identifier in the updated local span of configuration list, wherein the response to the configuration query message includes the DHCP configuration information currently present on the at least one host.
12. The DHCP server recited in claim 11 , wherein the one or more processors are further configured to:
update the mate span of configuration list on the mate DHCP server based on the one or more differences between the local span of configuration list and the mate span of configuration list in response to mate DHCP server failing.
13. The DHCP server recited in claim 9 , wherein the DHCP server comprises a recovering DHCP server that provisions the IP configuration information to the one or more hosts in combination with a mate DHCP server in a redundant deployment, wherein the mate DHCP server is a failover resource that communicates for the DHCP server in response to a failure associated therewith, and the one or more processors are further configured to:
receive, from a DHCP summary node, summarized DHCP configuration information that corresponds to one or more hosts in a subnetwork managed with the DHCP summary node, wherein the DHCP configuration information currently present on the one or more hosts includes the summarized DHCP configuration information received from the DHCP summary node.
14. The DHCP server recited in claim 9 , wherein the one or more processors are further configured to:
determine that the DHCP configuration information currently present on at least one host that corresponds to a unique identifier stored in the non-volatile memory cannot be obtained from the network; and
provision the at least one host with new DHCP configuration information, wherein the DHCP configuration information currently present on the one or more hosts includes the new DHCP configuration information provisioned to the at least one host.
15. A non-transitory computer-readable storage medium having computer-executable instructions recorded thereon, wherein executing the computer-executable instructions on a Dynamic Host Configuration Protocol (DHCP) server causes the DHCP server to:
store, in non-volatile memory, unique identifiers that correspond to one or more hosts in a network that the DHCP server has provisioned with Internet Protocol (IP) configuration information, wherein the unique identifiers uniquely identify the one or more hosts in a routing domain associated with an Open Shortest Path First (OSPF) area, a routing IP address, a subnet mask, and a gateway, wherein the DHCP server provisions the IP configuration information to the one or more hosts in a standalone deployment;
obtain, from the network, DHCP configuration information currently present on the one or more hosts that correspond to the unique identifiers stored in the non-volatile memory in response to the DHCP server failing;
repopulate a DHCP database associated with the DHCP server based on the DHCP configuration information currently present on the one or more hosts;
send a configuration query message to each host that corresponds to a unique identifier stored in the non-volatile memory; and
receive a response to the configuration query message from at least one host that corresponds to a unique identifier stored in the non-volatile memory, wherein the response to the configuration query message includes the DHCP configuration information currently present on the at least one host.
16. The non-transitory computer-readable storage medium recited in claim 15 , wherein the DHCP server comprises a recovering DHCP server that provisions the IP configuration information to the one or more hosts in combination with a mate DHCP server in a redundant deployment, wherein the mate DHCP server is a failover resource that communicates for the DHCP server in response to a failure associated therewith.