US-12621236-B2 - LAG 1+1 handoff between packet and OTN

US12621236B2US 12621236 B2US12621236 B2US 12621236B2US-12621236-B2

Abstract

A network element includes a plurality of ports including a first set of ports configured to connect to a router via a Link Aggregation and a second set of ports configured to communicatively connect to another network element via 1+1 protection over a Time Division Multiplexing (TDM) network; and circuitry interconnecting the plurality of ports and configured to perform a first bridge and select function to convert the Link Aggregation protection associated with the first set of ports to a single connection, and perform a second bridge and select function to convert the single connection to the 1+1 protection associated with the second set of ports. The first bridge and select function and the second bridge and select function are each configured to close one type of protection and open another type of protection.

Inventors

Alexander Young
Rajagopalan Kannan
Kalp Desai
Chandrasekhar Viswanathan
Matthew Yuen
Sitaram Patro
Matthew Danby Jemmeson

Assignees

CIENA CORPORATION

Dates

Publication Date: 20260505
Application Date: 20231211
Priority Date: 20231027

Claims (20)

1 . A network element comprising: a plurality of ports including a first set of ports configured to connect to a router via a Link Aggregation and a second set of ports configured to communicatively connect to another network element via 1+1 protection over a Time Division Multiplexing (TDM) network; and circuitry interconnecting the plurality of ports and configured to perform a first bridge and select function to convert the Link Aggregation protection associated with the first set of ports to a single connection, wherein the first bridge and select function comprises a virtual switch implementing an Ethernet Tree (ETREE) having two leaf ports on a fabric-facing side of the ETREE coupled to the single connection and a root port on a router-facing side of the ETREE coupled to the first set of ports, and wherein the circuitry is further configured to select between the leaf ports by ingress squelching which performs blocking in a break-before-make manner on an inactive path using an Interlaken (ILKN) interface in response to a status evaluation of the 1+1 protection based on at least one working-path status indicator and at least one protection-path status indicator, and perform a second bridge and select function to convert the single connection to the 1+1 protection associated with the second set of ports.
2 . The network element of claim 1 , wherein the first bridge and select function and the second bridge and select function are each configured to close one type of protection and open another type of protection, and wherein the ingress squelching via the Interlaken (ILKN) interface facilitates closing the Link Aggregation protection.
3 . The network element of claim 1 , further comprising a TDM switching fabric configured to switch the single connection.
4 . The network element of claim 1 , wherein, to perform the second bridge and select function, the circuitry is configured to implement (1) a bridge of the single connection to the second set of ports and (2) a select from the second set of ports to the single connection.
5 . The network element of claim 1 , wherein, to perform the first bridge and select function, the circuitry is configured to implement a packet Link Aggregation Group (LAG) which utilizes a virtual switch in the terminal network element and the Ethernet Tree (ETREE) to (1) select from the first set of ports to the single connection and (2) bridge from the single connection to the first set of ports.
6 . The network element of claim 1 , wherein the TDM network utilizes Optical Transport Network (OTN).
7 . The network element of claim 6 , wherein, to perform the first bridge and select function, the circuitry is configured to implement an OTN Link Aggregation Group (LAG) which (1) manually introduces errors on an inactive leg of the first set of ports to select from the first set of ports to the single connection and (2) bridges from the single connection to the first set of ports.
8 . The network element of claim 1 , wherein, to perform the first bridge and select function, the circuitry is configured to (1) manually introduce errors on an inactive leg of the first set of ports to select from the first set of ports to the single connection and (2) bridge from the single connection to the first set of ports.
9 . The network element of claim 1 , wherein, responsive to a failure in the TDM network, the circuitry is configured to holdoff protection switching to the Link Aggregation so that the 1+1 protection is implemented first.
10 . A method comprising steps of: performing a first bridge and select function to convert Link Aggregation protection associated a first set of ports, configured to connect to a router via a Link Aggregation, to a single connection, wherein the first bridge and select function comprises a virtual switch implementing an Ethernet Tree (ETREE) having two leaf ports on a fabric-facing side of the ETREE coupled to the single connection and a root port on a router-facing side of the ETREE coupled to the first set of ports, and wherein the steps further include selecting between the leaf ports by ingress squelching which performs blocking in a break-before-make manner on an inactive path using an Interlaken (ILKN) interface in response to a status evaluation of 1+1 protection based on at least one working-path status indicator and at least one protection-path status indicator; and performing a second bridge and select function to convert the single connection to the 1+1 protection associated with a second set of ports, configured to communicatively connect to a network element over a Time Division Multiplexing (TDM) network.
11 . The method of claim 10 , wherein the first bridge and select function and the second bridge and select function are each configured to close one type of protection and open another type of protection, and wherein the ingress squelching via the Interlaken (ILKN) interface facilitates closing the Link Aggregation protection.
12 . The method of claim 10 , wherein the steps further include switching the single connection via a TDM switching fabric; and implementing the first bridge and select function and the second bridge and select function, via the TDM switching fabric.
13 . The method of claim 10 , wherein the performing the second bridge and select function includes implementing (1) a bridge of the single connection to the second set of ports and (2) a select from the second set of ports to the single connection.
14 . The method of claim 10 , wherein the performing the first bridge and select function includes implementing a packet Link Aggregation Group (LAG) which utilizes a virtual switch and the Ethernet Tree (ETREE) to (1) select from the first set of ports to the single connection and (2) bridge from the single connection to first set of ports.
15 . The method of claim 10 , wherein the TDM network utilizes Optical Transport Network (OTN).
16 . The method of claim 15 , wherein the performing the first bridge and select function includes implementing an OTN Link Aggregation Group (LAG) which (1) manually introduces errors on an inactive leg of the first set of ports to select from the first set of ports to the single connection and (2) bridges from the single connection to the first set of ports.
17 . The method of claim 10 , wherein the performing the first bridge and select function includes manually introducing errors on an inactive leg of the first set of ports to select from the first set of ports to the single connection and (2) bridge from the single connection to the first set of ports.
18 . The method of claim 10 , wherein the steps further include responsive to a failure in the TDM network, holding off protection switching to the Link Aggregation so that the 1+1 protection is implemented first.
19 . A switching circuit configured to perform steps of: performing a first bridge and select function to convert Link Aggregation protection associated with a first set of ports, configured to connect to a router via a Link Aggregation, to a single connection, wherein the first bridge and select function comprises a virtual switch implementing an Ethernet Tree (ETREE) having two leaf ports on a fabric-facing side of the ETREE coupled to the single connection and a root port facing on a router-facing side of the ETREE coupled the first set of ports, and wherein the switching circuit is further configured to select between the leaf ports by ingress squelching which performs blocking in a break-before-make manner on an inactive path using an Interlaken (ILKN) interface in response to a status evaluation of 1+1 protection based on at least one working-path status indicator and at least one protection-path status indicator, and performing a second bridge and select function to convert the single connection to the 1+1 protection associated with a second set of ports, configured to communicatively connect to a network element over a Time Division Multiplexing (TDM) network.
20 . The switching circuit of claim 19 , wherein the first bridge and select function and the second bridge and select function are each configured to close one type of protection and open another type of protection, and wherein the ingress squelching via the Interlaken (ILKN) interface facilitates closing the Link Aggregation protection.

Description

FIELD OF THE DISCLOSURE The present disclosure relates generally to networking and computing. More particularly, the present disclosure relates to systems and methods for a Link Aggregation Group (LAG) 1+1 handoff between a packet network and Optical Transport Network (OTN). BACKGROUND OF THE DISCLOSURE Networks are realized at various layers including Layer 1 which uses Time Division Multiplexing (TDM) such as OTN and Layer 2 for packets such as Ethernet. Of note, an end-to-end service may include various domains such as a packet domain, i.e., User-Network Interface (UNI), at a first router or packet switch and at a second router or packet switch, and an optical domain, i.e., Network-Network Interfaces (NNIs), interconnecting the first router/packet switch and the second router/packet switch. The end-to-end service can require protection where the service is able to reroute due to faults (e.g., fiber cut, equipment failure, etc.). An example of protection includes so called 1+1 where there is a working path with a corresponding protection path. If there is a fault on the working path, the service switches to the protection path. For example, 1+1 can be used in an OTN network. Another example of protection includes a Link Aggregation Group (LAG) in the packet domain. Link Aggregation is described, e.g., in IEEE 802.1AX-2020, Standard for Local and Metropolitan Area Networks-Link Aggregation, the contents of which are incorporated by reference in their entirety. A LAG combines multiple parallel packet ports into a single logical link and can be used to protect the packet domain, i.e., when one or more of the parallel packet ports fail, the remaining ports can provide resilience. Again, an end-to-end service (which is also referred to herein as just a service) can include both a Layer 1 and Layer 2 component, each of which can include their own protection, e.g., 1+1 at Layer 1 and LAG at Layer 2. BRIEF SUMMARY OF THE DISCLOSURE The present disclosure relates to systems and methods for a Link Aggregation Group (LAG) 1+1 handoff between a packet network and Optical Transport Network (OTN). The present disclosure addresses the problem of how to connect to routers across an OTN network with no single point of failure and independent failure tolerance in fault domains A, B, C, where domains A and C are the routers and domain B is the OTN network interconnecting the routers. Logically, to provide a LAG 1+1 handoff, the present disclosure includes two separate bridge and select functions, one in the packet domain and one in the OTN domain. An end-to-end service will include two of these LAG 1+1 handoffs, namely between the domains A, B and the domains B, C. Two example implementations are described of the logical two separate bridge and select functions, namely an OTN LAG drop handoff approach and a packet LAG handoff approach. The OTN LAG drop handoff approach involves injection of Remote Fault (RF) defect to control the LAG selection and distribution while still providing awareness of genuine LAG leg faults. The packet LAG approach involves a Virtual Local Area Network (VLAN) Ethernet Tree (ETREE) construct to perform packet layer bridging from the packet to TDM domain and ingress control via Interlaken (ILKN) to convert TDM bridging function to a LAG like distribution function in the direction from TDM domain to L2. In an embodiment, a network element includes a plurality of ports including a first set of ports configured to connect to a router via a Link Aggregation and a second set of ports configured to communicatively connect to another network element via 1+1 protection over a Time Division Multiplexing (TDM) network; and circuitry interconnecting the plurality of ports and configured to perform a first bridge and select function to convert the Link Aggregation protection associated with the first set of ports to a single connection, and perform a second bridge and select function to convert the single connection to the 1+1 protection associated with the second set of ports. The first bridge and select function and the second bridge and select function can each be configured to close one type of protection and open another type of protection. The network element can further include a TDM switching fabric configured to switch the single connection. To perform the second bridge and select function, the circuitry can be configured to implement (1) a bridge of the single connection to the second set of ports and (2) a select from the second set of ports to the single connection. To perform the first bridge and select function, the circuitry can be configured to implement a packet Link Aggregation Group (LAG) which utilizes a virtual switch in the terminal network element and an Ethernet Tree (ETREE) to (1) select from the first set of ports to the single connection and (2) bridge from the single connection to the first set of ports. The TDM network can utilize Optical Transport Network (OTN). To perform the firs