# US 8,751,683 B2 · Failure protection in a provider backbone bridge network using selective redirection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,751,683 B2 - Document ID: US8751683B2 - Status: Granted - Kind: B2 - Application number: 11/972,173 - Filed: 2008-01-10 - Published: 2008-09-18 - Granted: 2014-06-10 - Earliest claimed: 2007-03-13 - Assignees: Alcatel Lucent - Applicants: Florin Balus; Kendall William Harvey; Joe Regan; Paul Kwok - Inventors: Florin Balus; Kendall William Harvey; Joe Regan; Paul Kwok - Web page: https://patentgrep.com/patent/US8751683B2 ## CPC - H04L 45/28: using route fault recovery - H04L 12/462: {LAN interconnection over a bridge based backbone} - H04L 45/00: Routing or path finding of packets in data switching networks (routing or path finding in wireless networks H04W40/00) - H04L 45/22: {Alternate routing} - G06F 3/0635: {by changing the path, e.g. traffic rerouting, path reconfiguration} - H04L 45/08: {Learning-based routing, e.g. using neural networks or artificial intelligence} - H04L 45/66: {Layer 2 routing, e.g. in Ethernet based MAN's} - H04L 2012/5627: {Fault tolerance and recovery} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract A technique for operating a network involves controlling the black-holing of traffic by selectively redirecting unicast traffic destined for a dual-homed customer equipment (CE) device from a first provider backbone bridge (PBB) provider edge (PE) device to a second PBB PE device in response to a service failure. Unicast traffic is selectively redirected from the first PBB PE device to the second PBB PE device for a time interval that is long enough to enable the customer source MAC address (CMAC)-to-backbone MAC address (BMAC) association of the second PBB PE device to be learned by other PBB PE devices. ## Claims ### Claim 1 A method for operating a network that utilizes provider backbone bridging (PBB) according to IEEE 802.1 ah to create a PBB domain, wherein the network includes a first customer edge (CE) device connected to first and second PBB provider edge (PE) devices such that the first CE device is dual-homed to the first and second PBB PE devices and a second CE device connected to a third PBB PE device, the method comprising: creating a backup link between the first and second PBB PE devices, the backup link identifying customer MAC addresses (CMACs) for which unicast Ethernet traffic can be redirected from the first PBB PE device to the second PBB PE device; detecting a service failure that requires a path change for customer Ethernet traffic to reach the first CE device from the second CE device; selectively redirecting only unicast Ethernet traffic, which is destined to the first CE device, from the first PBB PE device to the second PBB PE device via the backup link in response to the detected service failure; preventing multicast Ethernet traffic and broadcast Ethernet traffic from being redirected from the first PBB device to the second PBB PE device; and preventing the second PBB PE device from performing MAC learning on the redirected unicast Ethernet traffic. ### Claim 2 (depends on 1) The method of claim 1 wherein unicast Ethernet traffic is redirected for a limited pre-defined interval. ### Claim 3 (depends on 2) The method of claim 2 further comprising learning, at the third PBB PE device, CMAC-to-BMAC associations that map a CMAC from a customer domain to a BMAC of the first PBB PE device, wherein the limited pre-defined interval is a time interval that is longer than an aging time interval of the CMAC-to-BMAC associations at the third PBB PE. ### Claim 4 (depends on 1) The method of claim 1 further comprising, at the third PBB PE device, learning a new CMAC-to-BMAC association that maps the CMAC to the BMAC of the second PBB PE device. ### Claim 5 (depends on 4) The method of claim 4 further comprising sending unicast Ethernet traffic from the second CE device to the first CE device via the second PBB PE device according to the newly learned CMAC-to-BMAC association. ### Claim 6 (depends on 1) The method of claim 1 wherein selectively redirecting unicast Ethernet traffic comprises redirecting only known unicast Ethernet traffic that is associated with the backup link. ### Claim 7 (depends on 1) The method of claim 1 further comprising, at the second PBB PE device, flooding the redirected unicast Ethernet traffic only in customer domains corresponding to the redirected unicast Ethernet traffic. ### Claim 8 (depends on 1) The method of claim 1 further comprising preventing the second PBB PE device from forwarding the unicast Ethernet traffic towards the PBB domain. ### Claim 9 A network device for use in a network that utilizes provider backbone bridging (PBB) according to IEEE 802.1 ah to create a PBB domain, wherein the network includes a first customer edge (CE) device connected to first and second PBB provider edge (PE) devices such that the first CE device is dual-homed to the first and second PBB PE devices and a second CE device connected to a third PBB PE device, the network device comprising: means for creating a backup link between the first and second PBB PE devices, the backup link identifying customer MAC addresses (CMACs) for which unicast Ethernet traffic can be redirected from the first PBB PE device to the second PBB PE device; means for detecting a service failure that requires a path change for customer Ethernet traffic to reach the first CE device from the second CE device; means for selectively redirecting only unicast Ethernet traffic, which is destined to the first CE device, from the first PBB PE device to the second PBB PE device via the backup link in response to the detected service failure; means for preventing multicast Ethernet traffic and broadcast Ethernet traffic from being redirected from the first PBB device to the second PBB PE device; and means for preventing the second PBB PE device from performing MAC learning on the redirected unicast Ethernet traffic. ### Claim 10 (depends on 9) The network device of claim 9 wherein unicast Ethernet traffic is redirected for a limited pre-defined interval. ### Claim 11 (depends on 10) The network device of claim 10 wherein the limited pre-defined interval is a time interval that is longer than an aging time interval of CMAC-to-BMAC associations at the third PBB PE. ### Claim 12 (depends on 9) The network device of claim 9 wherein creating the backup link comprises identifying CMACs that are reachable from the second PBB PE device. ### Claim 13 (depends on 9) The network device of claim 9 wherein selectively redirecting Ethernet unicast traffic comprises redirecting only known unicast traffic that is associated with the backup link. ### Claim 14 A method for operating a network that utilizes provider backbone bridging (PBB) according to IEEE 802.1ah to create a PBB domain, wherein the network includes a first customer edge (CE) device connected to first and second PBB provider edge (PE) devices such that the first CE device is dual-homed to the first and second PBB PE devices and a second CE device connected to a third PBB PE device, the method comprising: at the third PBB PE device, learning a CMAC-to-BMAC association that maps a customer MAC (CMAC) from a customer domain to a backbone MAC of the first PBB PE device; sending unicast Ethernet traffic from the second CE device to the first CE device via the first PBB PE device according to the CMAC-to-BMAC association; detecting a service failure that requires a path change for customer Ethernet traffic to reach the first CE device from the second CE device; selectively redirecting only unicast Ethernet traffic, which is destined to the first CE device, from the first PBB PE device to the second PBB PE device via the backup link in response to the detected service failure and preventing multicast Ethernet traffic and broadcast Ethernet traffic from being redirected from the first PBB device to the second PBB PE device; at the second PBB PE device, preventing the second PBB PE device from performing MAC learning on the redirected unicast Ethernet traffic; at the third PBB PE device, learning a new CMAC-to-BMAC association that maps the CMAC to the BMAC of the second PBB PE device; and sending unicast Ethernet traffic from the second CE device to the first CE device via the second PBB PE device according to the newly learned CMAC-to-BMAC association. ### Claim 15 (depends on 14) The method of claim 14 wherein selectively redirecting unicast Ethernet traffic comprises creating the backup link between the first and second PBB PE devices, the backup link identifying customer MAC addresses (CMACs) for which unicast Ethernet traffic can be redirected from the first PBB PE device to the second PBB PE device. ### Claim 16 (depends on 15) The method of claim 15 wherein unicast Ethernet traffic is redirected for a limited pre-defined interval. ### Claim 17 (depends on 16) The method of claim 16 wherein the limited pre-defined interval is a time interval that is longer than an aging time interval of the CMAC-to-BMAC associations at the third PBB PE.