Forwarding path failure detection using packet loop
AssigneeArista Networks, Inc.
InventorsRajshekhar Biradar, Naveen Kumar Devaraj
Life of this patent
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Abstract
A packet loop runs between two participating endpoint network devices, and in particular runs in the respective data planes of the endpoint devices. A probe packet is provided to the data plane of an initiating device and is forwarded to the other device to initiate the packet loop. The source and destination addresses in the probe packet are set equal to a common address. Based on the common address, entries in the respective forwarding tables of the endpoint devices are established to point to each other so that the probe packet is forwarded back and forth between the two devices thus sustaining the packet loop. A broken loop indicates a forwarding path failure at which time corrective action to be taken.
Claims20
A method in a first network node for monitoring a data forwarding path between the first network node and a second network node, the method comprising the first network node:
- transmitting a probe packet to the second network node, the probe packet being contained in a first packet, the first packet having an outer destination address set to an address of the second network node, the probe packet having an inner source address and an inner destination address both set to a same predetermined address;
- receiving the probe packet from the second network node, the probe packet being contained in a second packet having an outer destination address determined based on a mapping in the second network node that maps the predetermined address contained in the inner destination address of the probe packet to the first network node;
- and
- forwarding the probe packet received from the second network node in another instance of the first packet having an outer destination address set in accordance with the predetermined address contained in the inner destination address of the probe packet, wherein a mapping in the first network node maps the predetermined address to the second network node to initiate a packet loop that continuously forwards the probe packet between the first network node and the second network node.
A network device comprising:
- a processor;
- and
- control logic which, when operated, controls the processor to operate the network device as an initiating network device to:
- transmit an encapsulated probe packet to a participating network device, the probe packet having an inner source address and an inner destination address both set to a same predetermined address;
- receive the probe packet from the participating network device, the probe packet being returned to the initiating network device based on a first mapping that maps the predetermined address contained in the inner destination address of the probe packet to the initiating network device;
- and
- forward another instance of the probe packet to the participating network device based on a second mapping that maps the predetermined address to the participating network device to initiate a packet loop that continuously forwards the probe packet between the initiating network device and the participating network device.
A network device comprising:
- a processor;
- and
- control logic which, when operated, controls the processor to operate the network device to:
- receive packets sent from a sending device;
- periodically inspect a hit bit associated with a predetermined address to determine whether the hit bit is set to a first value or a second value;
- and
- signal an alarm in response to determining that the hit bit is set to the second value,
- wherein:
- the hit bit associated with the predetermined address is set to the first value each time a received packet has encapsulated therein a probe packet that includes an inner source address and an inner destination address that are both set to the predetermined address, and
- the hit bit associated with the predetermined address is set to the second value after a predetermined period of time has passed without receiving a packet having a probe packet that includes an inner source address and an inner destination address that are both set to the predetermined address.
Dependencies are inferred from the claim text.