Obtaining Internet Protocol Subnet Scope

Abstract

A method for obtaining and utilizing internet protocol (IP) subnet information, the method may include obtaining by a layer two cable modem termination system (L2 CMTS) information about IP subnets that comprise DHCP leased IP addresses assigned to devices serviced by the L2 CMTS; and maintaining, by the L2 CMTS and based on the information about the IP subnets, a data structure that reflects the IP subnets that comprise the IP addresses that are allocated to the devices serviced by the L2 CMTS.

We claim: 
     
         1 . A method for obtaining and utilizing internet protocol (IP) subnet information, the method comprises:
 obtaining by a layer two cable modem termination system (L2 CMTS) information about IP subnets that comprise Dynamic Host Configuration Protocol (DHCP) leased IP addresses assigned to devices serviced by the L2 CMTS; and   maintaining, by the L2 CMTS and based on the information about the IP subnets, a data structure that reflects the IP subnets that comprise the IP addresses that are allocated to the devices serviced by the L2 CMTS.   
     
     
         2 . The method according to  claim 1  wherein the devices serviced by the L2 CMTS are cable modems. 
     
     
         3 . The method according to  claim 1  wherein the devices serviced by the L2 CMTS are cable modems and additional devices coupled to the cable modems. 
     
     
         4 . The method according to  claim 1  wherein the maintaining of information about the IP subnets comprises relaying, by the L2 CMTS, DHCP messages between devices serviced by the L2 CMTS and at least one DHCP server, wherein a DHCP message exchanged between a device serviced by the L2 CMTS and a DHCP server comprises (a) an IP address dynamically allocated to the device by the DHCP server, and (b) an IP subnet identifier that identifies an IP subnet that comprises the device IP address. 
     
     
         5 . The method according to  claim 1  further comprising establishing by the L2 CMTS a status of a DHCP relay agent. 
     
     
         6 . The method according to  claim 1  further comprising receiving a request, from a requesting entity, related to IP subnets serviced by the L2 CMTS, retrieving from the data structure information related to the IP subnets serviced by the L2 CMTS; and sending to the requesting entity a response indicative of the information related to the IP subnets serviced by the L2 CMTS. 
     
     
         7 . The method according to  claim 1  further comprising receiving a request, from a requesting entity, related to an IP address of a device serviced by the L2 CMTS; and sending a response with information related to the IP subnet comprising the IP address of the device. 
     
     
         8 . The method according to  claim 1  wherein the maintaining of information about the IP subnets comprises requesting by the L2 CMTS and from a layer three edge router information about the IP subnets that comprise leased IP addresses assigned to devices serviced by the L2 CMTS and receiving by the L2 CMTS the information about the IP subnets. 
     
     
         9 . A layer two cable modem termination system (L2 CMTS) that comprises:
 a communication module and extraction modules that are arranged to obtain information about Internet protocol (IP) subnets that comprise Dynamic Host Configuration Protocol (DHCP) leased IP addresses assigned to devices serviced by the L2 CMTS; and   a data structure generator that is arranged to maintain, based on the information about the IP subnets, a data structure that reflects the IP subnets that comprise the IP addresses that are allocated to the devices serviced by the L2 CMTS.   
     
     
         10 . The L2 CMTS according to  claim 9  wherein the devices serviced by the L2 CMTS are cable modems. 
     
     
         11 . The L2 CMTS according to  claim 9  wherein the devices serviced by the L2 CMTS are cable modems and additional devices coupled to the cable modems. 
     
     
         12 . The L2 CMTS according to  claim 9  wherein the communication module is arranged to relay DHCP messages between devices serviced by the L2 CMTS and at least one DHCP server, wherein a DHCP message exchanged between a device serviced by the L2 CMTS and a DHCP server comprises (a) an IP address dynamically allocated to the device by the DHCP server, and (b) an IP subnet identifier that identifies an IP subnet that comprises the device IP address. 
     
     
         13 . The L2 CMTS according to  claim 9  further arranged to establish a status of a DHCP relay agent. 
     
     
         14 . The L2 CMTS according to  claim 9  wherein the communication module is further arranged to receive a request, from a requesting entity, related to IP subnets serviced by the L2 CMTS, retrieve from the data structure information related to the IP subnets serviced by the L2 CMTS; and send to the requesting entity a response indicative of the information related to the IP subnets serviced by the L2 CMTS. 
     
     
         15 . The L2 CMTS according to  claim 9  wherein the communication module is arranged to receive a request, from a requesting entity, related to an IP address of a device serviced by the L2 CMTS; and send a response with information related to the IP subnet comprising the IP address of the device. 
     
     
         16 . The L2 CMTS according to  claim 9  wherein the communication module is arranged to request from a layer three edge router information about the IP subnets that comprise leased IP addresses assigned to devices serviced by the L2 CMTS and receive by the L2 CMTS the information about the IP subnets. 
     
     
         17 . A non-transitory computer readable medium that stores instructions that once executed by a computer of a layer two cable modem termination system (L2 CMTS) cause the computer of the L2 CMTS to perform the stages of: obtaining information about IP subnets that comprise Dynamic Host Configuration Protocol (DHCP) leased IP addresses assigned to devices serviced by the L2 CMTS; and maintaining, based on the information about the IP subnets, a data structure that reflects the IP subnets that comprise the IP addresses that are allocated to the devices serviced by the L2 CMTS. 
     
     
         18 . The non-transitory computer readable medium according to  claim 17  that stores instructions for maintaining of information about the IP subnets comprises relaying DHCP messages between devices serviced by the L2 CMTS and at least one DHCP server, wherein a DHCP message exchanged between a device serviced by the L2 CMTS and a DHCP server comprises (a) an IP address dynamically allocated to the device by the DHCP server, and (b) an IP subnet identifier that identifies an IP subnet that comprises the device IP address. 
     
     
         19 . The non-transitory computer readable medium according to  claim 17  that stores instructions for receiving a request, from a requesting entity, related to IP subnets serviced by the L2 CMTS, retrieving from the data structure information related to the IP subnets serviced by the L2 CMTS; and sending to the requesting entity a response indicative of the information related to the IP subnets serviced by the L2 CMTS. 
     
     
         20 . The non-transitory computer readable medium according to  claim 17  that stores instructions for receiving a request, from a requesting entity, related to an IP address of a device serviced by the L2 CMTS; and sending to the requesting entity a response with information related to the IP subnet comprising the IP address of the device. 
     
     
         21 . The non-transitory computer readable medium according to  claim 17  that stores instructions for requesting by the L2 CMTS and from a layer three edge router information about the IP subnets that comprise leased IP addresses assigned to devices serviced by the L2 CMTS and receiving by the L2 CMTS the information about the IP subnets.