# US 2019/0356599 A1 · Method and system for core network support of access network protocols in multi-homed redundancy groups

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- Number: US 2019/0356599 A1
- Document ID: US20190356599A1
- Status: Published application
- Kind: A1
- Application number: 15/980,466
- Filed: 2018-05-15
- Published: 2019-11-21
- Earliest claimed: 2018-05-15
- Assignees: Cisco Technology, Inc.
- Applicants: Cisco Technology, Inc.
- Inventors: Patrice Brissette; Ali Sajassi; Mei Zhang; Luc Andre Burdet
- Web page: https://patentgrep.com/patent/US20190356599A1

## CPC

- H04L 47/25: with rate being modified by the source upon detecting a change of network conditions
- H04L 12/18: for broadcast or conference {, e.g. multicast}
- H04L 12/1836: {with heterogeneous network architecture}
- H04L 12/46: Interconnection of networks
- H04L 12/4641: {Virtual LANs, VLANs, e.g. virtual private networks [VPN] (LAN interconnection over a bridge based backbone H04L12/462; encapsulation techniques H04L12/4633; routing of packets H04L45/00; packet switches H04L49/00; virtual private networks for security H04L63/0272)}
- H04L 12/4675: {Dynamic sharing of VLAN information amongst network nodes (configuration of the network or of network elements H04L41/08)}
- H04L 12/66: Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
- H04L 41/0654: using network fault recovery (ring fault isolation or reconfiguration in loop networks without recovery actions by a network management system H04L12/437)
- H04L 41/0677: Localisation of faults
- H04L 41/12: Discovery or management of network topologies
- H04L 45/02: Topology update or discovery
- H04L 45/16: Multipoint routing
- H04L 45/18: Loop-free operations
- H04L 45/26: {Route discovery packet}
- H04L 45/28: using route fault recovery
- H04L 45/50: using label swapping, e.g. multi-protocol label switch [MPLS]
- H04L 45/507: {Label distribution}
- H04L 45/66: {Layer 2 routing, e.g. in Ethernet based MAN's}
- H04L 47/10: Flow control; Congestion control
- H04L 47/125: by balancing the load, e.g. traffic engineering
- H04L 47/15: {in relation to multipoint traffic (arrangements for broadcast or multicast in data networks H04L12/18)}
- H04L 47/806: {Broadcast or multicast traffic}
- H04L 47/829: {Topology based}
- H04L 49/201: Multicast operation; Broadcast operation
- H04L 49/354: for supporting virtual local area networks [VLAN]
- H04L 49/65: Re-configuration of fast packet switches
- H04L 69/18: Multiprotocol handlers, e.g. single devices capable of handling multiple protocols
- H04L 69/26: {Special purpose or proprietary protocols or architectures (network applications for proprietary or special purpose networking environments H04L67/12)}
- H04L 69/30: Definitions, standards or architectural aspects of layered protocol stacks
- H04L 69/322: Intralayer communication protocols among peer entities or protocol data unit [PDU] definitions
- H04L 69/324: in the data link layer [OSI layer 2], e.g. HDLC
- H04L 69/40: for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection (management of faults, events, alarms or notifications in data switching networks H04L41/06)
- H04L 41/34: Signalling channels for network management communication
- H04L 41/344: Out-of-band transfers
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

In one embodiment, a method according to the present disclosure includes receiving a topology change message at a core edge node and performing a network address information removal operation. The core edge node participates in network communications with one or more access network nodes of an access network using an access network protocol. The topology change message indicates that a topology change has occurred in the access network, and the topology change message conforms to the access network protocol. The network address information removal operation removes network address information stored by the core edge node, and the network address information is used by the core edge node in participating in the network communications.

## Claims

### Claim 1

A method comprising:
receiving a topology change message at a core edge node, wherein
the core edge node participates in network communications with one or more access network nodes of an access network using an access network protocol,
the topology change message indicates that a topology change has occurred in the access network, and
the topology change message conforms to the access network protocol; and
performing a network address information removal operation, wherein
the network address information removal operation removes network address information stored by the core edge node, and
the network address information is used by the core edge node in participating in the network communications.

### Claim 2 (depends on 1)

The method of claim 1, wherein the core edge node is one of a plurality of core nodes in a core network, and the method further comprises:
advertising the network address information removal operation by sending an advertisement to at least one other core node of the plurality of core nodes.

### Claim 3 (depends on 2)

The method of claim 2, wherein
the core edge node is comprised in a plurality of core edge nodes comprised in a redundancy group,
prior to the sending of the advertisement,
the core edge node was in communication with a remote core edge node of the plurality of core nodes in support of a flow, and
the core edge node and another core edge node of the plurality of core edge nodes were communicatively coupled to one another by a communication path, and
the method further comprises
upon receiving a network communication from the remote core edge node subsequent to the sending of the advertisement, communicating the network communication to the another core edge node.

### Claim 4 (depends on 2)

The method of claim 2, wherein the at least one other core node is a remote core edge node of the plurality of core nodes, and the method further comprises:
receiving the advertisement at the remote core edge node; and
in response to receipt of the advertisement by the remote core edge node, performing another network address information removal operation, wherein
the another network address information removal operation removes other network address information stored by the remote core edge node.

### Claim 5 (depends on 4)

The method of claim 4, wherein the core edge node is comprised in a plurality of core edge nodes comprised in a redundancy group, and further comprising:
determining whether to flood one or more packets to the plurality of core edge nodes; and
in response to a determination to flood the one or more packets, flooding the one or more packets to the plurality of core edge nodes.

### Claim 6 (depends on 4)

The method of claim 4, wherein
prior to receipt of the advertisement, the remote core edge node supported a flow by communicating with the core edge node,
the core edge node is comprised in a plurality of core edge nodes comprised in a redundancy group, and
the method further comprises
determining whether to use a multicast communications technique to support the flow, and
in response to a determination that the multicast communications technique should be used to support the flow, causing the remote core edge node to communicate with the plurality of core edge nodes using the multicast communications technique.

### Claim 7 (depends on 2)

The method of claim 2, further comprising:
sending a configuration message to a remote core edge node of the plurality of core nodes;
receiving the configuration message at the remote core edge node; and
in response to receipt of the configuration message at the remote core edge node,
disabling aliasing,
disabling split-horizon filtering, and
disabling a backup route.

### Claim 8 (depends on 1)

The method of claim 1, wherein the core edge node is one of a plurality of core nodes in a core network, the topology change message comprises topology change information, and the method further comprises:
in response to receipt of the topology change message,
determining whether topology change information is to be communicated to another core edge node, wherein
the core edge node and the another core edge node are comprised in a redundancy group, and
in response to a determination that the topology change information is to be communicated to the another core edge node, communicating the topology change information to the another core edge node.

### Claim 9 (depends on 1)

The method of claim 1, further comprising:
determining whether the topology change has affected reachability of a computing device communicatively coupled to the access network, wherein
the reachability of the computing device is determined for a flow; and
in response to a determination that the topology change has affected reachability of the computing device, re-advertising route information for the flow.

### Claim 10 (depends on 1)

The method of claim 1, wherein
the access network protocol is a gateway protocol,
the core edge node is an edge node of a core network,
the core network supports an Ethernet virtual private network (EVPN) protocol by implementing a multiprotocol label switching (MPLS) protocol.

### Claim 11 (depends on 10)

The method of claim 10, wherein
the access network protocol is a gateway protocol, and
the network address information removal operation removes one or more network addresses from a forwarding table maintained by the core edge node.

### Claim 12 (depends on 1)

The method of claim 1, wherein the core edge node is one of a plurality of core nodes in a core network, and the method further comprises:
identifying a plurality of core edge nodes of the plurality of core nodes as being members of a redundancy group, wherein
the plurality of core edge nodes comprises the core edge node,
the access network comprises a plurality of access network nodes, and
each of the plurality of core edge nodes is communicatively coupled to one or more of the plurality of access network nodes; and
configuring a communications path between the core edge node and another core edge node of the plurality of core edge nodes.

### Claim 13

A network device comprising:
one or more processors, wherein
the network device is a core edge node;
a first network interface, coupled to the one or more processors and configured to be coupled to an access network;
a second network interface, coupled to the one or more processors and configured to be coupled to a core network;
a memory, coupled to the one or more processors and configured to store network address information;
a computer-readable storage medium, coupled to the one or more processors; and
a plurality of instructions, encoded in the computer-readable storage medium and configured to cause the one or more processors to
receive a topology change message at the first network interface, wherein
the core edge node is configured to participate in network communications with one or more access network nodes of an access network using an access network protocol via the first network interface,
the core edge node is configured to participate in other network communications with one or more core nodes of a core network using a core network protocol via the second network interface,
the topology change message indicates that a topology change has occurred in the access network, and
the topology change message conforms to the access network protocol; and
perform a network address information removal operation, wherein
the network address information removal operation removes the network address information stored in the memory, and
the network address information is used by the core edge node in participating in the network communications.

### Claim 14 (depends on 13)

The network device of claim 13, wherein the core edge node is one of a plurality of core nodes in a core network, and the plurality of instructions are further configured to cause the one or more processors to:
advertise the network address information removal operation by sending an advertisement to at least one other core node of the plurality of core nodes, wherein
the core edge node is comprised in a plurality of core edge nodes comprised in a redundancy group, and
prior to the advertisement being sent,
the core edge node was in communication with a remote core edge node of the plurality of core nodes in support of a flow, and
the core edge node and another core edge node of the plurality of core edge nodes were communicatively coupled to one another by a communication path; and
upon receiving a network communication from the remote core edge node subsequent to the sending of the advertisement, communicate the network communication to the another core edge node.

### Claim 15 (depends on 13)

The network device of claim 13, wherein the core edge node is one of a plurality of core nodes in a core network, the topology change message comprises topology change information, and the plurality of instructions are further configured to cause the one or more processors to:
in response to receipt of the topology change message,
determine whether topology change information is to be communicated to another core edge node, wherein
the core edge node and the another core edge node are comprised in a redundancy group, and
in response to a determination that the topology change information is to be communicated to the another core edge node, communicate the topology change information to the another core edge node.

### Claim 16 (depends on 13)

The network device of claim 13, wherein the plurality of instructions are further configured to cause the one or more processors to:
determine whether the topology change has affected reachability of a computing device communicatively coupled to the access network, wherein
the reachability of the computing device is determined for a flow; and
in response to a determination that the topology change has affected reachability of the computing device, re-advertise route information for the flow.

### Claim 17

A computer program product comprising:
a plurality of instructions, comprising
a first set of instructions, executable by a processor of a core edge node, configured to receive a topology change message, wherein
the core edge node is configured to participate in network communications with one or more access network nodes of an access network using an access network protocol,
the topology change message indicates that a topology change has occurred in the access network, and
the topology change message conforms to the access network protocol; and
a second set of instructions, executable by the processor, configured to perform a network address information removal operation, wherein
the network address information removal operation removes network address information stored in a memory of the core edge node,
the memory and the processor are coupled to one another and
the network address information is used by the core edge node in participating in the network communications; and
a non-transitory computer-readable storage medium, wherein the instructions are encoded in the computer-readable storage medium.

### Claim 18 (depends on 17)

The computer program product of claim 17, wherein the core edge node is one of a plurality of core nodes in a core network, and the instructions further comprise:
a third set of instructions, executable by the processor, configured to advertise the network address information removal operation by sending an advertisement to at least one other core node of the plurality of core nodes, wherein
the core edge node is comprised in a plurality of core edge nodes comprised in a redundancy group, and
prior to the advertisement being sent,
the core edge node was in communication with a remote core edge node of the plurality of core nodes in support of a flow, and
the core edge node and another core edge node of the plurality of core edge nodes were communicatively coupled to one another by a communication path; and
a fourth set of instructions, executable by the processor, configured to, upon receiving a network communication from the remote core edge node subsequent to the sending of the advertisement, communicate the network communication to the another core edge node.

### Claim 19 (depends on 17)

The computer program product of claim 17, wherein the core edge node is one of a plurality of core nodes in a core network, the topology change message comprises topology change information, and the instructions further comprise:
a third set of instructions, executable by the processor, configured to, in response to receipt of the topology change message,
determine whether topology change information is to be communicated to another core edge node, wherein
the core edge node and the another core edge node are comprised in a redundancy group, and
in response to a determination that the topology change information is to be communicated to the another core edge node, communicate the topology change information to the another core edge node.

### Claim 20 (depends on 17)

The computer program product of claim 17, wherein the instructions further comprise:
a third set of instructions, executable by the processor, configured to determine whether the topology change has affected reachability of a computing device communicatively coupled to the access network, wherein
the reachability of the computing device is determined for a flow; and
a fourth set of instructions, executable by the processor, configured to in response to a determination that the topology change has affected reachability of the computing device, re-advertise route information for the flow.