EXTERNALLY INITIATED APPLICATION SESSION ENDPOINT MIGRATION

摘要

In storage networks (e.g., SAN and NAS), various reasons can arise for migrating an application layer communication session endpoint to a different host. To achieve scalability and robustness, the migration can be enacted externally and carried out at a middlebox at the transport layer. When a migration is triggered to migrate an application layer communication session endpoint from a host A to a host B, the middlebox coordinates network address translation with a transport protocol reset mechanism to switch the connection to host B and close the connection on host A with minimal disruption to the non-migrating application layer communication session endpoint using the connection. At the application layer, the non-migrating application layer communication session endpoint will initiate a new connection in response to detecting the reset, and retry any operation that was aborted as a result of the connection switch.

主权项

1. A method comprising:
determining that an endpoint of an application communication session is to be migrated from a first host to a second host, wherein the application communication session uses a transport layer connection for a communications between the first host and a third host; configuring, in a middlebox, a first network address translation rule to translate an address of the first host to an address of the second host for protocol data units associated with the transport layer connection and being transmitted to the first host from the third host; configuring, in the middlebox, a second network address translation rule to translate the address of the second host to the address of the first host for protocol data units associated with the transport layer connection and being transmitted to the third host from the second host; creating, in the middlebox, an acknowledgement message as if from the third host and with an acknowledgement number that is not expected by the first host; transmitting the acknowledgment message to the first host; after receipt of an acknowledgement message from the first host, creating a reset message as if from the third host, wherein the reset message is created with a sequence field set to an acknowledgment number indicated in the acknowledgement message from the first host; and transmitting the reset message to the first host.