Cisco Technology, Inc.

David P Toscano

David Delano Ward

Reshad Rahman

Sylvain Masse

Christian E Hopps

Neil R Ketley

Jonathan Parker

Jean-Marc Simard

Puneet Gupta

Sunil K Srivastava

Reshad A Rahman

In one embodiment, a plurality of links between a network node and another network node are configured as a link bundle. The network node establishes one or more standby bidirectional forwarding detection (BFD) sessions. Each standby BFD session is associated with one or more links of the link bundle. The network node establishes an active BFD session. The active BFD session is associated with one or more links of the link bundle. In response to non-receipt of returned BFD messages for the active BFD session, one or more new active BFD sessions are selected from the one or more standby BFD sessions. In response to non-receipt of returned BFD messages for the one or more new active BFD sessions, it is determined that the link bundle has failed.

Technique for efficiently and dynamically maintaining bidirectional forwarding detection on a bundle of links

In one embodiment, a local network device transmits a connectivity verification protocol control message over a link to a remote network device to attempt to establish a connectivity verification protocol session with the remote network device. In response to non-receipt of a returned connectivity verification protocol control message from the remote network device, the local network device determines that there is an inability to establish a connectivity verification protocol session with the remote network device. The local network device then sends a connectivity verification protocol echo message over the link to the remote network device without establishment of a connectivity verification protocol session. The echo message is sent using a forwarding protocol. In response to receipt of a reply to the connectivity verification protocol echo message from the remote network device, the local network device determines that the forwarding protocol is functioning and uses the link to forward data traffic to the remote network device.

Distinguishing between connectivity verification availability and forwarding protocol functionality in a computer network

A technique efficiently and dynamically maintains bidirectional forwarding detection (BFD) on a bundle of links in a computer network. According to the novel technique, one or more 'standby' BFD sessions may be established on one or more corresponding line cards (LCs), the LCs having one or more links of the bundle (bundle links). Once established, one of the standby BFD sessions may be selected as an 'active' BFD session based on activity of one of the bundle links of the corresponding LC. Also, BFD messages may be transmitted from one of the bundle links of the active BFD session, e.g., the link receiving BFD messages. In response to inactivity of the transmitting link (e.g., failure, removal, etc.), the active BFD session may switch to another available active bundle link, and if no other active bundle links are available to the active BFD session, one of the standby BFD sessions is selected as the new active BFD session. In the event no other standby BFD sessions exist, the link bundle is determined to have failed.

In one embodiment, a local network device may determine an inability to establish a connectivity verification protocol (e.g., Bidirectional Forwarding Detection, 'BFD') session to a remote network device, such as from unreturned control messages. In response, the local network device may send at least one connectivity verification protocol echo message to the remote network device destined to be returned to the local network device and forwarded using a forwarding protocol. In response to receiving or not receiving the echo message, the local network device may thus determine whether the forwarding protocol is functioning between the local and remote network devices. In this manner, the local network device may determine whether an inability to establish a connectivity verification protocol session is due to an inability to forward packets between the devices, or due to the connectivity verification protocol not working (or not being configured) on the remote network device.

In one embodiment, an apparatus includes a physical port and a plurality of logical sub-interfaces under the physical port. The physical port and the logical sub-interfaces are configured as a Bidirectional Forwarding Detection (BFD) neighbor group. The physical port being configured to run BFD sessions to detect failures at a first rate that is substantially faster as compared to a second rate of BFD sessions to detect failures on the logical sub-interfaces. The physical port notifies the logical sub-interfaces of a BFD failure at the physical port, with the logical sub-interfaces shutting down responsive to the notification.

Scaling BFD sessions for neighbors using physical / sub-interface relationships

A system and method for bidirectional forwarding detection (BFD) rate-limiting and automatic BFD session activation includes tracking a total bidirectional forwarding detection (BFD) packet rate for a line card (LC) of the node, and rejecting operations associated with creation of a new BFD session that would cause the total BFD packet rate to exceed a predetermined maximum rate. The new BFD session is stored in a state on the node and the operations of the new BFD session are automatically retried at a time when doing so would not exceed the predetermined maximum rate.

BFD rate-limiting and automatic session activation

A system and method for bidirectional forwarding detection (BFD) rate-limiting and automatic BFD session activation includes tracking a total bidirectional forwarding detection (BFD) packet rate for a line card (LC) of the node, and rejecting operations associated with creation of a new BFD session that would cause the total BFD packet rate to exceed a predetermined maximum rate. The new BFD session is stored in a state on the node and the operations of the new BFD session are automatically retried at a time when doing so would not exceed the predetermined maximum rate. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

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Ottawa, Canada

David P Toscano