# US 2014/0153573 A1 · System and method for scaling ipv6 addresses in a network environment > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0153573 A1 - Document ID: US20140153573A1 - Status: Published application - Kind: A1 - Application number: 13/705,273 - Filed: 2012-12-05 - Published: 2014-06-05 - Earliest claimed: 2012-12-05 - Assignees: Cisco Technology, Inc. - Inventors: Chengelpet V. Ramesh; Ming Zhang; Shyam Kapadia; Sankararaman Jayaraman - Web page: https://patentgrep.com/patent/US20140153573A1 ## CPC - H04L 45/748: using longest matching prefix - H04L 45/741: Routing in networks with a plurality of addressing schemes, e.g. with both IPv4 and IPv6 - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract An example method is provided and includes receiving, at an ingress switch in a network, a packet from an attached host that is coupled to a destination host, where the packet includes an Internet Protocol version 6 (IPv6) address of a destination host, comparing the IPv6 address with a plurality of entries in a longest prefix match (LPM) table, in which each entry includes a value string and a corresponding mask string configured to detect a match for a specific combination of a segment prefix and a switch-id in the IPv6 address, identifying an egress switch from a matching entry in the LPM table, and forwarding the packet to the egress switch. The IPv6 address includes a combination of segment prefix and switch-id associated with the egress switch. The segment prefix corresponds to an identifier of a network segment, and the switch-id corresponds to an identifier of a switch in the network. ## Claims ### Claim 1 A method, comprising: receiving, at an ingress switch in a network, a packet from an attached host that is coupled to a destination host, wherein the packet includes an Internet Protocol version 6 (IPv6) address of the destination host; comparing the IPv6 address with a plurality of entries in a longest prefix match (LPM) table, wherein each entry comprises a value string and a corresponding mask string configured to detect a match for a specific combination of a segment prefix and a switch-id in the IPv6 address, wherein the segment prefix comprises a first 48 bits and the switch-id comprises a penultimate 16 bits in the IPv6 address; identifying an egress switch from a matching entry in the LPM table; and forwarding the packet to the egress switch. ### Claim 2 (depends on 1) The method of claim 1, wherein the IPv6 address includes a combination of segment prefix and switch-id associated with the egress switch. ### Claim 3 (depends on 1) The method of claim 1, further comprising: receiving the packet at the egress switch; looking up a host table comprising IPv6 addresses and corresponding ports of directly attached hosts; and forwarding the packet to the IPv6 address of the destination host. ### Claim 4 (depends on 1) The method of claim 1, wherein if no match is found, a destination host is identified. ### Claim 5 (depends on 1) The method of claim 1, wherein the switch-id comprises an emulated switch-id for a host connected to an emulated switch, wherein the emulated switch comprises a pair of switches connected to the host and appearing as a single switch to the network. ### Claim 6 (depends on 1) The method of claim 1, wherein if no match is found in the LPM table, forwarding the packet to a border switch to send the packet out of the network. ### Claim 7 (depends on 1) The method of claim 1, wherein the segment prefix corresponds to an identifier of a network segment, and the switch-id corresponds to an identifier of a switch in the network. ### Claim 8 (canceled) ### Claim 9 (depends on 1) The method of claim 1, wherein the mask string comprises a first portion and a second portion, wherein the first portion corresponds to the segment prefix, and the second portion corresponds to the switch-id. ### Claim 10 (depends on 1) The method of claim 1, wherein the plurality of entries in the LPM table may be independent of subnets configured on the ingress switch. ### Claim 11 Logic encoded in non-transitory media that includes instructions for execution and when executed by a processor, is operable to perform operations comprising: receiving, at an ingress switch in a network environment, a packet from an attached host that is coupled to a destination host, wherein the packet includes an IPv6 address of a destination host; comparing the IPv6 address with a plurality of entries in a LPM table, wherein each entry comprises a value string and a corresponding mask string configured to detect a match for a specific combination of a segment prefix and a switch-id in the IPv6 address, wherein the segment prefix comprises a first 48 bits and the switch-id comprises a penultimate 16 bits in the IPv6 address; identifying an egress switch from a matching entry in the LPM table; and forwarding the packet to the egress switch. ### Claim 12 (depends on 11) The logic of claim 11, wherein the IPv6 address includes a combination of segment prefix and switch-id associated with the egress switch. ### Claim 13 (depends on 11) The logic of claim 11, the operations further comprising: receiving the packet at the egress switch; looking up a host table comprising IPv6 addresses and corresponding ports of directly attached hosts; and forwarding the packet to the IPv6 address of the destination host. ### Claim 14 (depends on 11) The logic of claim 11, wherein the mask string comprises a first portion and a second portion, wherein the first portion corresponds to the segment prefix, and the second portion corresponds to the switch-id. ### Claim 15 (depends on 11) The logic of claim 11, wherein the segment prefix corresponds to an identifier of a network segment, and the switch-id corresponds to an identifier of a switch in the network. ### Claim 16 An apparatus, comprising: a lookup module; a forward module; a memory element for storing data; and a processor that executes instructions associated with the data, wherein the lookup module, the forward module, the processor, and the memory element cooperate such that the apparatus is configured for: receiving, at the apparatus, a packet from an attached host that is coupled to a destination host, wherein the packet includes an IPv6 address of a destination host; comparing the IPv6 address with a plurality of entries in the LPM table, wherein each entry comprises a value string and a corresponding mask string configured to detect a match for a specific combination of a segment prefix and a switch-id in the IPv6 address, wherein the segment prefix comprises a first 48 bits and the switch-id comprises a penultimate 16 bits in the IPv6 address; identifying an egress switch from a matching entry in the LPM table; and forwarding the packet to the egress switch. ### Claim 17 (depends on 16) The apparatus of claim 16, wherein the IPv6 address includes a combination of segment prefix and switch-id associated with the egress switch. ### Claim 18 (depends on 16) The apparatus of claim 16, wherein the mask string comprises a first portion and a second portion, wherein the first portion corresponds to the segment prefix, and the second portion corresponds to the switch-id. ### Claim 19 (depends on 16) The apparatus of claim 16, wherein the segment prefix corresponds to an identifier of a network segment, and the switch-id corresponds to an identifier of a switch in the network. ### Claim 20 (canceled) ### Claim 21 (depends on 16) The apparatus of claim 16, wherein the egress switch receives the packet, looks up a host table comprising IPv6 addresses and corresponding ports of directly attached hosts, and forwards the packet to the IPv6 address of the destination host.