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A METHOD FOR REUSING A TCP FASTOPEN COOKIE ACROSS MULTIPLE SERVER IP ADDRESSES

IP.com Disclosure Number: IPCOM000244822D
Publication Date: 2016-Jan-19
Document File: 7 page(s) / 45K

Publishing Venue

The IP.com Prior Art Database

Related People

Andrew Yourtchenko: AUTHOR [+3]

Abstract

A method is provided for reusing the Transmission Control Protocol (TCP) Fast Open cookie, the method comprising either one or both of first and second approaches. The first approach involves explicitly having a server supply together with TCP Fast Open Cookie the prefix length that this Cookie covers. The second approach involves the client doing a best-match of previously contacted servers, and attempting to reuse the cookie from another server to make the new connection, and if that cookie works, use this fact to make more general assumptions for future connections.

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A METHOD FOR REUSING A TCP FASTOPEN COOKIE ACROSS MULTIPLE SERVER IP ADDRESSES

AUTHORS:

Andrew Yourtchenko Mark Townsley Mohammed Hawari

CISCO SYSTEMS, INC.

ABSTRACT

    A method is provided for reusing the Transmission Control Protocol (TCP) Fast Open cookie, the method comprising either one or both of first and second approaches. The first approach involves explicitly having a server supply together with TCP Fast Open Cookie the prefix length that this Cookie covers. The second approach involves the client doing a best-match of previously contacted servers, and attempting to reuse the cookie from another server to make the new connection, and if that cookie works, use this fact to make more general assumptions for future connections.

DETAILED DESCRIPTION

    There are two approaches for reusing the TCP Fast Open cookie when communicating with multiple servers. A first approach: explicitly have the server supply together with TCP Fast Open Cookie the prefix length that this Cookie covers; a second approach: have the client do best-match of previously contacted servers, and attempt to reuse the cookie from another server to make the new connection, and if that cookie works, use this fact to make more general assumptions for future connections. Applying the regular TCP Fast Open mechanism does not help in the case of multiple connections to many jointly-administered servers, and involves useless memory overhead if the number of these servers is large. The described mechanism allows saving of round-trip times when connecting to many servers within the same administration/security domain.

Copyright 2016 Cisco Systems, Inc.

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First Approach-Explicit Signaling from Server

    The first approach involves explicit signaling from the server, which complements the cookie sent to the client by the prefix length for which this cookie is supposed to be shared. This asserts that every server in this prefix will have the same parameters for the cookie validation function. Thus the client can reuse the same cookie and shortcut the three way handshake for any new connection whose destination address falls within the prefix length signaled to the client by the first server. This method requires the modification to the protocol on the wire, thus possibly standardization.

Proposed Extension to TCP Fast Open(TFO) [RFC7413] for First Approach:

    When a server receives a TCP SYN packet asking for a TFO cookie, it generates a TFO cookie and sends a TCP SYN+ACK with the TFO cookie and the prefix length for which the TFO cookie is valid, thus allowing the client to reuse the cookie for the whole prefix comprising the server. A new TCP Option named TCP Fast Open Prefix Length (TFOPL) is specified. The value of this option is the prefix length (in bits) for which a TCP Fast Open (TFO) cookie is valid.

    Client Behavior: When the client requests a TFO cookie, it MAY include in the TCP SYN packet a TFOPL Option comprising the value zero and an empty TFO cookie....